tag:blogger.com,1999:blog-11067220703953279992024-02-01T20:21:28.086-08:00electrical engineering constructionbasic electrical, power plant, electrical building, lightning protectiontambarihttp://www.blogger.com/profile/00551341351972304033noreply@blogger.comBlogger59125tag:blogger.com,1999:blog-1106722070395327999.post-28217022552468248822010-02-22T19:48:00.000-08:002010-02-22T19:54:40.688-08:00Ground Loop Basics<a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgjFOu4W6imT2nGEViKZkYgngui1FqX0Ciux7aSsJ6v4Ze-eModudzdHwCEB8fZYuum5e1P-Tf_JhnxDHUPP45QWkfrYqBzD_F2TaEX_OraHlKfTUMbZHkWttQUD-OeoQug-iz_zS33vQF7/s1600-h/gndloop.gif"><img style="margin: 0pt 10px 10px 0pt; float: left; cursor: pointer; width: 320px; height: 171px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgjFOu4W6imT2nGEViKZkYgngui1FqX0Ciux7aSsJ6v4Ze-eModudzdHwCEB8fZYuum5e1P-Tf_JhnxDHUPP45QWkfrYqBzD_F2TaEX_OraHlKfTUMbZHkWttQUD-OeoQug-iz_zS33vQF7/s320/gndloop.gif" alt="" id="BLOGGER_PHOTO_ID_5441282309662533042" border="0" /></a><br /><div style="text-align: justify;">What is ground loop ?<br />A ground loop occurs when there is more than one ground connection path between two pieces of equipment. The duplicate ground paths form the equivalent of a loop antenna which very efficiently picks up interference currents. Lead resistance transforms these currents into voltage fluctuations. As a consequence of ground-loop induced voltages, the ground reference in the system is no longer a stable potential, so signals ride on the noise. The noise becomes part of the program signal.<br /><br />Ground loop is a common wiring conditions where a ground current may take more than one path to return to the grounding electrode at the SERVICE PANEL. AC powered computers all connected to each other through the ground wire in common building wiring. Computers may also be connected by data communications cables. Computers are therefore frequently connected to each other through more than one path. When a multi-path connection between computer circuits exists, the resulting arrangement is known as a "ground loop". Whenever a ground loop exists, there is a potential for damage from INTER SYSTEM GROUND NOISE.<br /><br />A ground loop in the power or video signal occurs when some components in the same system are receiving its power from a different ground than other components, or the ground potential between two pieces of equipment is not identical.<br /><br />Usually a potential difference in the grounds causes a current to flow in the interconnects. This in turn modulates the input of the circuitry and is treated like any other signal fed through the normal inputs. Here is an example situation where two grounde equipments are interconnected though signal wire ground and the mains grounding wire. In this situation there is 1A current flowing flowing in the wire which causes 0.1V voltage difference between those two equipemt grounding points.<br /><br />Example of groundloop problem in system interconnection<br />Because there is voltage difference between the ewuipments, the signal in the interconnection wire sees that difference added to signal. This canbe heard as humming noise on the wire because the AC current cause the voltage difference of those ground potentials to be also AC voltage. This is one reason for this 50 Hz or 60 Hz noise you hear in the audio signal (or see in video signal as annoying horizonal bars).<br /><br />Another problem is the current flowing in the signal cable grounding wire. This current passes though the cable and through the equipment. Of the way the curren parsses is not weel designed this can cause lots noise to the equipment or other kind of problems (like computer lockups). Lots of designers count on ground being ground and do not optimize their design to eliminate their sensitivity to ground noise. If you are a product desiger remeber to take care that ground loop current does not cause problems in your equipment by designing proper grounding scheme inside the equipment.<br /><br />Why ground loop is a problem ?<br />Ground loop is a common problem when connecting multiple audio-visual system components together, there is a good change of making a nasty ground loops. Ground loop problems are one of the most common noise problems in audio systems. Typical indication of the ground loop problem is audible 50 Hz or 60 Hz (depends on mains voltage frequency used in your country) noise in sound. Most common situation where you meet ground loop problems are when your system includes equipment connected to earthed elecric outlet and antenna network or equipments connected to different grounded outlets around the room.<br /><br />Everything connected to a single mains earth, which is usually connected to all the earth pins in all the power sockets in one room. Then antenna network is also grounded to same grounding point. This would normally be okay, as the grounding is only connected to each other in a star-like fashion from a central earth wire (leading to the real Earth via a grounding cable or metal pipe) earth cables run through your power cables into the equipment.<br /><br />Once you take into account that some of your equipment is linked with shielded cable you are quite likely to face some problems. Currents could quite possibly run from one piece of equipment, into the earth cable, into another piece of equipment, then back to the first piece via a shielded audio cable. That wire loop can also pick up interference from nearby magnetic fields and radio transmitters.<br /><br />The result is that the unwanted signal will be amplified until it is audible and clearly undesireable. Even voltage differences lower than 1 mV can cause annoying humming sound on your audio system.<br /><br />A problem with audible noise coming from your audio system when other electronic components (fridge, water cooler, ect.) could be the result of of a contaminated ground/neutral conductor in your A/C wiring and a ground loop in uour audio system. This can happen when certain type of devices come on. Typically their power supplies are non-linear and throw garbage back onto the neutral and/or ground conductors. Usually line conditioners or UPS devices will not do anything to help solve this problem.<br /><br />Common Causes for Computer System Problems<br />Many times when a user thinks that his system is 'bad' or has 'gone bad' the fault is electrical or magnetic in nature. Monitor problems are very often caused by nearby magnetic fields, neutral wire harmonics, or conducted/transmitted electrical noise. Intermittent lockups of computers are very often the caused by a Ground Loop, an electrical phenomena that sometimes manifests itself when a system and it's peripherals are improperly plugged into different electrical circuits. Many don't even know if their wall outlet is properly wired and grounded, an absolute necessity for a computer and peripheral to operate reliably and safely.<br /><br />Have you ruled out Ground Loops in your computer system ? Ground loops can cause problems to LAN connections if not properly wired. A ground loop caused by RS-232 connection to other computer can cause computer lockups.<br /><br />When ground loop is not a problem<br />Ground loop does not cause problems when all of the following thing are true:<br /> * None of the wires in the loop carry any current<br /> * The loop is not exposed to external changing magnetic fields<br /> * There is no radio frequency interference nearby<br />If there is any current folowing in any wires, there is then some potentital difference which causes current to flow in other wires also which causes problems. The loop will also act as coil and pick current from the changing magnetic fields around it. Wire loop acts also like an antenna picking up radio signals.<br /><br />What size of ground potential difference problems we are talking about ?<br />Literature is speaking about Common Mode Noise of 1 to 2 Volt in "well grounded" plants and over 20 Volts in "poorly grounded" plants. Literature is also speaking of the current measured on a main service grounding (in a large building) in terms of Amps.<br /><br />Where does this current and voltage difference come from ?<br />Current leakage of condensators between hot and ground and between neutral and ground, in for instance main filters, cause current in ground wires (and ground loops). The leakage current is typically measures in milliamperes (typically less than 1 mA in computer equipments) per equipment. When you sum up maybe hundreds of such equipments you can easyly get amperes.<br /><br />The capacitance between line and ground of large heaters and motors, for example, can be much larger than the capacitance in filter capacitors. Currents from this source are usually of the order of 1 amp (rather than 0.1 A or 10 A)<br /><br />Even a very small induced voltage can cause a very large current in a ground conductor loop, because the resistance (and inductance) are very low. These currents can indeed be tens of amps. Current induction can be caused for example by cables carrying high currents and from transformers.<br /><br />What those grounding currents and voltage differences can do ?<br />Small voltage differences just cause noise to be added to the signals. This can cause humming noise to audio, interference bars to video signals and transmission errors to computer networks.<br /><br />Higher currents can cause more serious problems like sparking in connections, damages equipment and burned wiring. My own experience on th field is limited to sparking connectors, heating cables and damaged computer serial port cards. I have read about burned signal cables and smoking computers because of the ground differentials and large currents caused by them. So be warned about this potential problem and do not do any stupid installations.<br /></div>tambarihttp://www.blogger.com/profile/00551341351972304033noreply@blogger.com2tag:blogger.com,1999:blog-1106722070395327999.post-37823556166501885972009-04-21T02:34:00.000-07:002009-04-21T22:37:01.797-07:00Geothermal Energy<div style="text-align: justify;">The term geothermal comes from the Greek geo, meaning earth, and therine, meaning heat, thus geothermal energy is energy derived from the natural heat of the earth. The earth’s temperature varies widely, and geothermal energy is usable for a wide range of temperatures from room temperature to well over 300°F. For commercial use, a geothermal reservoir capable of providing hydrothermal (hot water and steam) resources is necessary. Geothermal reservoirs are generally classified as being either low temperature (<150°c)>150°C). Generally speaking, the high temperature reservoirs are the ones suitable for, and sought out for, commercial production of electricity. Geothermal reservoirs are found in “geothermal systems,” which are regionally localized geologic settings where the earth’s naturally occurring heat flow is near enough to the earth’s surface to bring steam or hot water, to the surface. Examples of geothermal systems include the Geysers Region in Northern California, the Imperial Valley in Southern California, and the Yellowstone Region in Idaho, Montana, and Wyoming.<br /><br /><span style="font-weight: bold;">Dry Steam Power Plant</span><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEji9AfROHDwCwnvW207ae5B_j3VbNJAUEEr-ie8FV18MkY8lfxu5C5ahtS1Ccgaquh8mooFdeuTYK-SJU6hKkkaooUdFTEpAaq6LCFs-uFq32OdmebWvFPSbiNN_9gxTd0Q15rkhMeMpKdh/s1600-h/dry_steam.gif"><img style="margin: 0pt 10px 10px 0pt; float: left; cursor: pointer; width: 320px; height: 210px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEji9AfROHDwCwnvW207ae5B_j3VbNJAUEEr-ie8FV18MkY8lfxu5C5ahtS1Ccgaquh8mooFdeuTYK-SJU6hKkkaooUdFTEpAaq6LCFs-uFq32OdmebWvFPSbiNN_9gxTd0Q15rkhMeMpKdh/s320/dry_steam.gif" alt="" id="BLOGGER_PHOTO_ID_5327077241669677426" border="0" /></a>Power plants using dry steam systems were the first type of geothermal power generation plants built. They use steam from the geothermal reservoir as it comes from wells and route it directly through turbine/generator units to produce electricity. An example of a dry steam generation operation is at the Geysers Region in northern California.<br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><span style="font-weight: bold;">Flash Steam Power Plant</span><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi_4LvC6QIwjcAfzoMthyphenhyphenEW5muANIvFLEh49LcL_0RDmD0kNqoVJskw-6JDIdafD2gwYBTLEprV-X4ppMLfDCpmFeRBw4MytJMMY7pGEakdP21y_tDvl1RczT7_2_qRCGDFePOHj-LtyoQj/s1600-h/flash.gif"><img style="margin: 0pt 10px 10px 0pt; float: left; cursor: pointer; width: 320px; height: 213px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi_4LvC6QIwjcAfzoMthyphenhyphenEW5muANIvFLEh49LcL_0RDmD0kNqoVJskw-6JDIdafD2gwYBTLEprV-X4ppMLfDCpmFeRBw4MytJMMY7pGEakdP21y_tDvl1RczT7_2_qRCGDFePOHj-LtyoQj/s320/flash.gif" alt="" id="BLOGGER_PHOTO_ID_5327077568273323698" border="0" /></a>Flash steam plants are the most common type of geothermal power generation plants in operation today. They use water at temperatures greater than 360°F (182°C) that is pumped under high pressure to the generation equipment at the surface. Upon reaching the generation equipment, the pressure is suddenly reduced, allowing some of the hot water to convert or “flash” into steam. This steam is then used to power the turbine/generator units to produce electricity. The remaining hot water not flashed into steam, and the water condensed from the steam, is generally pumped back into the reservoir. An example of an area using the flash steam operation is the CalEnergy Navy I flash geothermal power plant at the Coso geothermal field.<br /><br /><br /><br /><br /><br /><span style="font-weight: bold;">Binary Cycle Power Plant</span><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhv_la95jqbTjvPytJpa2GHB4foMmhv7vfCOOEk0hdlsrbSygoX_FDhgKURK-YQPSX60xWJdbBRWuponVj5LDcFFU3JHrBAeFpvPH8zumTDmHFqN27QYZUtfTHOrXC8w98_HVTNgRZraVOc/s1600-h/binary.gif"><img style="margin: 0pt 10px 10px 0pt; float: left; cursor: pointer; width: 320px; height: 213px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhv_la95jqbTjvPytJpa2GHB4foMmhv7vfCOOEk0hdlsrbSygoX_FDhgKURK-YQPSX60xWJdbBRWuponVj5LDcFFU3JHrBAeFpvPH8zumTDmHFqN27QYZUtfTHOrXC8w98_HVTNgRZraVOc/s320/binary.gif" alt="" id="BLOGGER_PHOTO_ID_5327079822887113890" border="0" /></a>Binary cycle geothermal power generation plants differ from dry steam and flash steam systems because the water or steam from the geothermal reservoir never comes in contact with the turbine/generator units. In the binary system, the water from the geothermal reservoir is used to heat another “working fluid,” which is vaporized and used to turn the turbine/generator units. The geothermal water and the “working fluid” are each confined in separate circulating systems or “closed loops” and never come in contact with each other. The advantage of the binary cycle plant is that they can operate with lower temperature waters (225°F to 360°F) by using working fluids that have an even lower boiling point than water. They also produce no air emissions. An example of an area using a binary cycle power generation system is the Mammoth Pacific binary geothermal power plants at the Casa Diablo geothermal field.<br /><br /></div>tambarihttp://www.blogger.com/profile/00551341351972304033noreply@blogger.com4tag:blogger.com,1999:blog-1106722070395327999.post-40538596748276287122009-04-21T02:30:00.000-07:002009-04-21T02:34:07.641-07:00Coal Fire Power Plant<div style="text-align: justify;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjywasJ-CTUhFmZvddw5sBUY5YCHyrtUuOWuvx00Y_-cZwTWJSU0uUGxLP1dT9IC93PU33YT2YQD-ppO_z4gqCxyvB5CTgd-rj5eOV0wrXOYtsjRf5Knk152NTe5klJEqQWrmvxG_krPFfI/s1600-h/coalart.gif"><img style="margin: 0pt 10px 10px 0pt; float: left; cursor: pointer; width: 320px; height: 198px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjywasJ-CTUhFmZvddw5sBUY5YCHyrtUuOWuvx00Y_-cZwTWJSU0uUGxLP1dT9IC93PU33YT2YQD-ppO_z4gqCxyvB5CTgd-rj5eOV0wrXOYtsjRf5Knk152NTe5klJEqQWrmvxG_krPFfI/s320/coalart.gif" alt="" id="BLOGGER_PHOTO_ID_5327075484772690274" border="0" /></a>Coal-fired units produce electricity by burning coal in a boiler to heat water to produce steam. The steam, at tremendous pressure, flows into a turbine, which spins a generator to produce electricity. The steam is cooled, condensed back into water, and returned to the boiler to start the process over.<br /><br />For example, the coal-fired boilers at TVA’s Kingston Fossil Plant near Knoxville, Tennessee, heat water to about 1,000 degrees Fahrenheit (540 degrees Celsius) to create steam. The steam is piped to the turbines at pressures of more than 1,800 pounds per square inch (130 kilograms per square centimeter). The turbines are connected to the generators and spin them at 3600 revolutions per minute to make alternating current electricity at 20,000 volts. River water is pumped through tubes in a condenser to cool and condense the steam coming out of the turbines.<br /><br />The Kingston plant generates about 10 billion kilowatt-hours a year, or enough electricity to supply 700,000 homes. To meet this demand, Kingston burns about 14,000 tons of coal a day, an amount that would fill 140 railroad cars.<br /></div>tambarihttp://www.blogger.com/profile/00551341351972304033noreply@blogger.com0tag:blogger.com,1999:blog-1106722070395327999.post-19084765392139173342009-04-21T02:04:00.000-07:002009-04-21T02:24:14.557-07:00Power Transmission Line<span style="font-weight: bold;">Classification of transmission lines</span><br /><div style="text-align: justify;">Transmission lines are classified as short, medium and long. When the length of the line is less than about 80Km the effect of shunt capacitance and conductance is neglected and the line is designated as a short transmission line. For these lines the operating voltage is less than 20KV.<br /><br />For medium transmission lines the length of the line is in between 80km - 240km and the operating line voltage wil be in between 21KV-100KV.In this case the shunt capacitance can be assumed to be lumped at the middle of the line or half of the shunt capacitance may be considered to be lumped each end of the line.The two representations of medium length lines are termed as nominal-T and nominal- π respectively.<br /><br />Lines more than 240Km long and line voltage above 100KV require calculations in terms of distributed parameters.Such lines are known as long transmission lines.This classification on the basis of length is more or less arbitrary and the real criterion is the degree of accuracy required.<br /><br /><span style="font-weight: bold;">Performance of Transmission Lines</span><br />The performance of a power system is mainly dependent on the performance of the transmission lines in the system.It is necessary to calculate the voltage,current and power at any point on a transmission line provided the values at one point are known.<br /><br />The transmission line performance is governed by its four parameters - series resistance and inductance,shunt capacitance and conductance.All these parameters are distributed over the length of the line.The insulation of a line is seldom perfect and leakage currents flow over the surface of insulators especially during bad weather.This leakage is simulated by shunt conductance.The shunt conductance is in parallel with the system capacitance.Generally the leakage currents are small and the shunt conductance is ignored in calculations.<br />Performance of transmission lines is meant the determination of efficiency and regulation of lines.The efficiency of transmission lines is defined as<a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiItNFNd_XwIQrc19Zd6_LGLGNbE7bt5f6GIkkSTLwroY4SAc7eXj-EGfqHwAH4QRM_wScNaxv5Sha2sGVlfsQTrgwqWFgTQsYV3WJpfu7M9kQT_XOv1c1BBmhbwJ5QeQGJER7iTtA7gylR/s1600-h/tr+effic.jpg"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer; width: 350px; height: 43px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiItNFNd_XwIQrc19Zd6_LGLGNbE7bt5f6GIkkSTLwroY4SAc7eXj-EGfqHwAH4QRM_wScNaxv5Sha2sGVlfsQTrgwqWFgTQsYV3WJpfu7M9kQT_XOv1c1BBmhbwJ5QeQGJER7iTtA7gylR/s320/tr+effic.jpg" alt="" id="BLOGGER_PHOTO_ID_5327069901025663538" border="0" /></a>The end of the line where load is connected is called the receiving end and where source of supply is connected is called the sending end.<br /><br />The Regulation of a line is defined as the change in the receiving end voltage, expressed in percent of full load voltage, from no load to full load, keeping the sending end voltage and frequency constant.<a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhv6UywVdv3RdUqJq3rC8L6-X0zKZpJwb8-DcvLi_XGuu9TsjD4kX1ixNUdK2TO2Q7yjM0VCLL7_WZygv-4XKj9jtMMBNTzDlybB6e-aYloMjLQa-UqreovDiQ4CYtbuZ2EufdbVrLB8DDv/s1600-h/tr+regu.jpg"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer; width: 350px; height: 43px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhv6UywVdv3RdUqJq3rC8L6-X0zKZpJwb8-DcvLi_XGuu9TsjD4kX1ixNUdK2TO2Q7yjM0VCLL7_WZygv-4XKj9jtMMBNTzDlybB6e-aYloMjLQa-UqreovDiQ4CYtbuZ2EufdbVrLB8DDv/s320/tr+regu.jpg" alt="" id="BLOGGER_PHOTO_ID_5327070201012404818" border="0" /></a><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhv6UywVdv3RdUqJq3rC8L6-X0zKZpJwb8-DcvLi_XGuu9TsjD4kX1ixNUdK2TO2Q7yjM0VCLL7_WZygv-4XKj9jtMMBNTzDlybB6e-aYloMjLQa-UqreovDiQ4CYtbuZ2EufdbVrLB8DDv/s1600-h/tr+regu.jpg"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer; width: 320px; height: 54px;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhv6UywVdv3RdUqJq3rC8L6-X0zKZpJwb8-DcvLi_XGuu9TsjD4kX1ixNUdK2TO2Q7yjM0VCLL7_WZygv-4XKj9jtMMBNTzDlybB6e-aYloMjLQa-UqreovDiQ4CYtbuZ2EufdbVrLB8DDv/s320/tr+regu.jpg" alt="" id="BLOGGER_PHOTO_ID_5327070201012404818" border="0" /></a></div>tambarihttp://www.blogger.com/profile/00551341351972304033noreply@blogger.com1tag:blogger.com,1999:blog-1106722070395327999.post-59764696436530672912008-10-29T00:13:00.000-07:002008-10-29T00:21:56.728-07:00uninterruptible power supply (UPS)<div style="text-align: justify;">uninterruptible power supply (UPS) is an electronic device that continues to supply electric power to the load for a certain period of time during a loss of utility power or when the line voltage varies outside normal limits. Its typical application is computer backup power.<br /><br />The generic standard for UPS systems is <a href="http://www.amazon.com/gp/product/B000XYSBGI?ie=UTF8&tag=smpsunspun-20&linkCode=as2&camp=1789&creative=9325&creativeASIN=B000XYSBGI"target="new">IEC 62040-3</a>, which defines limits on the amplitude and duration of deviation of the output voltage acceptable for switching power supply (SMPS) loads.<br /><br />To make a power supply uninterruptible you need to add an energy storing backup battery, an AC-DC charger and an DC-AC inverter. There are three main types of UPS power backup devices: Standby, Line Interactive and Online. All of them use battery backup when the input fails, but under normal conditions they handle the power differently.<br /><br />Standby UPS includes a transfer switch that switches the load to the<br />battery / inverter should the primary AC power source fails. The typical transfer time is between 2 ms and 10 ms depending on the amount of time it takes to detect the lost utility voltage and turn on DC-AC inverter. During this time the power to the load is momentarily interrupted. The equipment's power supply should have hold up ("ride through") time larger then UPS transfer time to avoid data loss. For reference, a typical power factor corrected (PFC) SMPS of a personal computer has at least 10 to 20 ms hold-up time.<br />Since the inverter operates in standby mode and starts up only when input power fails, the SPS has the highest efficiency (95-97%) and reliability. Because it is also the cheapest UPS, it the most common backup type used for PCs. Note, in some older systems the inverter produced square-wave type output rather then sinusoidal, which could cause problems to sensitive equipment.<br /><br />The Ferroresonant type of Standby UPS has an additional ferroresonant transformer that shapes output voltage and stores some energy for a smoother transfer. Its main drawback is instability when it is loaded by an SMPS with PFC front end. For this reason such systems are no longer commonly used.<br /><br />Line Interactive UPS under normal condition smoothes and to some degree regulates the input AC voltage by a filter and a tap-changing transformer. The bi-directional inverter/charger is always connected to the output of the UPS and uses a portion of AC power to keep the battery charged. When the input power fails, the transfer switch disconnects AC input and the battery/inverter provides output power. Its typical efficiency is 90-96%. This type is currently the most common design in 0.5-5 kVA power range.<br /><br />Online UPS always delivers all or at least a portion of the output power through its inverter even under normal line conditions. There are two main types of on-line UPS: double conversion and delta conversion.<br /><br />Double Conversion Online UPS is continuously processing the whole power through series connected AC-DC rectifier / charger and DC-AC inverter. Although such type provides PFC and better output power quality then the previous types, the double conversion is resulting in reduced efficiency (80-90 % typical).<br /><br />Delta Conversion Online UPS includes an additional "Delta Converter" that delivers a portion of the input power directly to the load and provides power factor correction. Such partial bypassing the rectifier / inverter stages<br />during normal operation results in higher efficiency (up to 97%).</div>tambarihttp://www.blogger.com/profile/00551341351972304033noreply@blogger.com3tag:blogger.com,1999:blog-1106722070395327999.post-44566609486906411662008-09-15T20:58:00.000-07:002008-09-15T21:18:28.479-07:00Electrical Grid Code<div style="text-align: justify;"><span style="font-weight: bold;">Philippines Grid code</span><br />Energy Regulatory COmmision<br /><a href="http://www.napocor.gov.ph/pdfs/Philippine%20Grid%20Code.pdf">Download pdf</a><br /><br /><span style="font-weight: bold;">Grid Code</span><br />Department of Energy<br /><a href="http://www.doe.gov.ph/Downloads/Final_Grid_Code.pdf">Download pdf</a><br /><br /><span style="font-weight: bold;">Guidelines to Govern The Formartion of the Grid Management Committee</span><br />Department of Energy (DOE), Distribution Code.Distributor, Electric Cooperative, Energy Regulatory Commission (ERC)., Grid Code, Grid Management Committee (GMC)., Grid Owner., Large Customer., Large Generator, Market Operator., National Electrification Administration (NEA), Small Generator., Supplier, System Operator.<br /><a href="http://www.erc.gov.ph/cgi-bin/issuances/files/221_ERC%20Guidelines%20-%20GMC%20Formation.pdf">Download pdf</a><br /><br /><span style="font-weight: bold;">SA distributrion grid code development</span><br />Distribution Network Code (NC) , Distribution System Operating Code (OC),Distribution Metering Code (MC),Distribution Information Exchange Code (IC): first draft still under construction,Distribution Tariff Code (TC): first draft still under construction<br /><a href="http://www.eepublishers.co.za/view.php?sid=2045">View</a><br /><br /><span style="font-weight: bold;">Governance of Electrical Standards</span><br />With question and Answer portion at the free pdf file<br /><a href="http://www.ofgem.gov.uk/Networks/ElecDist/Policy/DistGen/Documents1/1040-Elexon.pdf">Download pdf</a><br /><br /><span style="font-weight: bold;">Grid Code Compliance - Voltage Aspects</span><br /><a href="http://www.bwea.com/pdf/realpower/rp05gridcode.pdf">Download pdf</a><br /><br /><span style="font-weight: bold;">Review Of The Grid Code</span><br />Decision and Notice in Relation to Consultation, COntrol Telephony Electrical Standard<br /><a href="http://www.nationalgrid.com/NR/rdonlyres/C9BA07A5-C5F3-4724-8F6B-E3966B997A85/19761/l07_051GridCodeC06Decision.pdf">Download pdf</a><br /><br /><span style="font-weight: bold;">DER Grid Interconnection Standard and Codes</span><br />Introduction, Activities and Results,National standards for interconnection of DER, Upgrade to the Canadian Electrical Code:,<br /><a href="http://cetc-varennes.nrcan.gc.ca/fichier.php/codectec/En/2007-228/2007-228_OP_411-INTERC_TIC706.1_martel_e.pdf">Download pdf</a><br /><br /><span style="font-weight: bold;">Mapping of grid faults and grid codes</span><br />Events in Electrical Network, Requirements for LVRT Capability in NationalGrid COdes, Fault Analysis, General Conclusion.<br /><a href="http://www.risoe.dk/rispubl/reports/ris-r-1617.pdf">Download pdf</a><br /><br /><span style="font-weight: bold;">Wind Energy and Grid Integration</span><br />Evolution of US Grid Code Activities, Summary of Wind Interconnection Best Practices, System Stability Case Study,<br /><a href="http://www.aeeolica.org/doc/CIE06_2_4_J_Charles_Smith.pdf">Download pdf</a><br /><br /><span style="font-weight: bold;">Interpreting the National Electrical Code</span><br />Beginning Special Applications Wiring<br /><a href="http://books.google.com.ph/books?id=Z4D-0J9R4QMC&pg=PA478&lpg=PA478&dq=grid+code+electrical&source=web&ots=Ue8pJkqo86&sig=Y_fHwRqRy_Iqx4ixc2ieTXL2wyU&hl=en">Preview</a><br /><br /><span style="font-weight: bold;">The Punjab State Electricity Regulatory Commision</span><br />General Code, Planning Code, Load Despatch & System Operation Code, Protection Code, Metering Code, Data Registration Code, Appendices<br /><a href="http://pserc.nic.in/pages/state_grid_code.html">Preview</a></div>tambarihttp://www.blogger.com/profile/00551341351972304033noreply@blogger.com0tag:blogger.com,1999:blog-1106722070395327999.post-31358427865237807022008-07-14T22:38:00.000-07:002008-07-14T22:44:46.544-07:00grounding electricityElectrical codes now require that all 120- and 240-volt circuits have a system of grounding. Grounding assures that all metal parts of a circuit that you might come in contact with are connected directly to the earth, maintaining them at zero voltage. This is a preventive measure. During normal operation, a grounding system does nothing; in the event of a malfunction, however, the grounding protects you and your home from electric shock or fire.<br /><div style="text-align: justify;"><br />To see why grounding is necessary, look at the drawing, which shows a circuit during normal conditions. Now let's take that same circuit and add a metal ceiling fixture. If the hot wire accidentally became dislodged from the fixture terminal and came into contact with the light fixture's metal canopy, which is highly conductive, the fixture would become electrically charged, or "hot." If you were to touch the fixture under those conditions, a current leakage, or "ground fault," could occur in which you would provide the path to ground for the electric current, and you would get a shock.<br /><br />The same result could occur in any number of places where electricity and conductive materials are together, such as in power tools and appliances with metal housings, in metal housing boxes, and in metal faceplates. In our example, shock could have been prevented if the circuit had had a grounding system. A grounding wire connecting the neutral bus bar in the service entrance panel to the metal housing of the light fixture would provide an auxiliary electrical path to ground. This grounding wire would carry the fault current back to the distribution center, where the fuse or circuit breaker protecting the circuit would open, shutting off all current flow.<br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEifwcANnvWn_1We7bxnQTks-BDvd2jPX7f8zAP5sphG0jsXD1zxTrYW4ivgrrP4_7Ca8l_8dCY76GnHFWuFXvhQMmUc8U8RL5m6f2bqHZMH34w0cDKBPTgXBDleiWawSFz1qVWF1o3bn1m-/s1600-h/ground+electric.bmp"><img style="margin: 0pt 10px 10px 0pt; float: left; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEifwcANnvWn_1We7bxnQTks-BDvd2jPX7f8zAP5sphG0jsXD1zxTrYW4ivgrrP4_7Ca8l_8dCY76GnHFWuFXvhQMmUc8U8RL5m6f2bqHZMH34w0cDKBPTgXBDleiWawSFz1qVWF1o3bn1m-/s400/ground+electric.bmp" alt="" id="BLOGGER_PHOTO_ID_5223112261950089058" border="0" /></a>In a typical house circuit, the wiring method dictates how grounding is done. When a home is correctly wired with armored cable, metal conduit, or flexible metal conduit, the metal enclosure can itself serve as the grounding path. But most modern construction uses nonmetallic sheathed cable (type NM), so a separate grounding wire must be run with the circuit wires. Running a separate grounding wire isn't as complicated as it may sound because NM cable contains a grounding wire.<br /><br />In any of these systems, the end result is the same: an auxiliary path for fault current is provided leading to the neutral bus bar in the service entrance panel, which is tied to ground via the grounding electrode conductor.<br /><br />In the drawing, the bare grounding wire of the NM cable provides the grounding continuity. The final grounding connection to the receptacle is made through a short piece of wire called a jumper that is bonded to the metal box with either a grounding screw or a grounding clip. If a nonmetallic box were used instead, the grounding wire would be connected directly to the receptacle because that kind of box needs no grounding.<br /><br />The ground fault circuit interrupter (GFCI or GFI) also protects against electric shock. Whenever the amounts of incoming and outgoing current are unequal, indicating current leakage, the GFCI opens the circuit instantly, cutting off the power. GFCIs are built to trip in 1/40th of a second in the event of a ground fault of 0.005 ampere.<br /><br />There are two types of GFCIs, both shown. The GFCI breaker is installed in the service panel; it monitors the amount of current going to and coming from an entire circuit. A GFCI receptacle monitors the flow of electricity to that receptacle, as well as to all devices installed in the circuit from that point onward (called "downstream").<br /><br />The electrical code now requires that receptacles in bathrooms, kitchens, garages, and outdoor locations (in other words, any potentially damp location where the risk of shock is greatest) be protected by a GFCI. You can use either type to serve these areas.</div>tambarihttp://www.blogger.com/profile/00551341351972304033noreply@blogger.com0tag:blogger.com,1999:blog-1106722070395327999.post-60501083913529666112008-06-12T01:59:00.000-07:002008-06-12T02:56:28.551-07:00Transformer Theory<a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg14vNa-RK7ivi1HGZiwVJyv8-6wOwlLEMvdus5gUkCXEUtmHjNsuLMNjmVaryHPtqiDinXN1INV5g6aLCZ1Cl2ud8yiQsvdsAK97IjBMIh_bi9lETmKimrKV0We57V_0SQ41Ma1os_PLS6/s1600-h/tr02.bmp"><img style="margin: 0pt 10px 10px 0pt; float: left; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg14vNa-RK7ivi1HGZiwVJyv8-6wOwlLEMvdus5gUkCXEUtmHjNsuLMNjmVaryHPtqiDinXN1INV5g6aLCZ1Cl2ud8yiQsvdsAK97IjBMIh_bi9lETmKimrKV0We57V_0SQ41Ma1os_PLS6/s400/tr02.bmp" alt="" id="BLOGGER_PHOTO_ID_5210927934727857138" border="0" /></a><br /><div style="text-align: justify;">High voltage DC, (Direct Current), transmission lines are the most efficient way to deliver electrical power over long distances with a minimum of loss to heat. However, before this electricity can be used, it must be inverted to AC, (Alternating Current), so that it can be transformed to a manageable voltage. Consequently, most distribution lines are AC voltages. Distribution of electrical power is done at a variety of different voltages, and voltage changes within a distribution system are accomplished by the use of transformers. Below is an example of a typical transformer, used in rural and residential areas of the United States.<br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgz5VxgXHZxanwOvCHU2g_Euqw-g5T2QO8mBkFgfn7iHMgnHIleJCQWu2ULv0LZk30DB_L_oJ0zwf_kiBDe9tolELwh-ZCPbUeYxwOdG4c8YBkFqp0FIg8tCP9CjGJK8Ks0mPPc3nEaAfDC/s1600-h/tr01.bmp"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgz5VxgXHZxanwOvCHU2g_Euqw-g5T2QO8mBkFgfn7iHMgnHIleJCQWu2ULv0LZk30DB_L_oJ0zwf_kiBDe9tolELwh-ZCPbUeYxwOdG4c8YBkFqp0FIg8tCP9CjGJK8Ks0mPPc3nEaAfDC/s400/tr01.bmp" alt="" id="BLOGGER_PHOTO_ID_5210922911993700578" border="0" /></a>In the image on the left, the tall insulators on the top of the transformer are the primary voltage terminals, and the smaller terminals on the side of the cylinder, are the secondary voltage connection points. These transformers are usually mounted to telephone poles, and a copper conductor is routed down the pole to a ground rod. This grounding conductor is attached to the center tap, or neutral terminal, and provides the neutral conductor with a reference to earth ground. Fuses are installed in the tap conductors, between the distribution lines and the primary voltage terminals, and a single transformer often serves several homes.<br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj20l2OFsXIMVSYErYzHOWYt-WeYlOGKNG0XwXgjGKihTTd89Rmu0uyFBrI_Xxt1yckq1v5BraR6VMSo2Ayjtjv1tqoTrDMxc3KOLy4U-KHCku37CQN43UQlE-H9J0aa39GUh2AISLUa2NK/s1600-h/Copy+of+tr01.bmp"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj20l2OFsXIMVSYErYzHOWYt-WeYlOGKNG0XwXgjGKihTTd89Rmu0uyFBrI_Xxt1yckq1v5BraR6VMSo2Ayjtjv1tqoTrDMxc3KOLy4U-KHCku37CQN43UQlE-H9J0aa39GUh2AISLUa2NK/s400/Copy+of+tr01.bmp" alt="" id="BLOGGER_PHOTO_ID_5210923218723940834" border="0" /></a>The voltage waveforms for the output of the transformer on the previous page look like this;<br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgyq8DlySYxw-At9D3UOILVzeOn2rrTLMyeVOz5qcSvQt6Ts8FIIWJgHKK1kzAsYNp8KxcFyH9j-iHk7oNguwiTXdh3Vnhb25PVtfBMMgErDwl_JmyxPvG7AZpz7-KedlESNq7UUZpD5TUG/s1600-h/tr03.bmp"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgyq8DlySYxw-At9D3UOILVzeOn2rrTLMyeVOz5qcSvQt6Ts8FIIWJgHKK1kzAsYNp8KxcFyH9j-iHk7oNguwiTXdh3Vnhb25PVtfBMMgErDwl_JmyxPvG7AZpz7-KedlESNq7UUZpD5TUG/s400/tr03.bmp" alt="" id="BLOGGER_PHOTO_ID_5210930458999646338" border="0" /></a>Industrial and commercial electrical systems differ from residential in a rather significant way. Three phase power is considerable more complex than single phase, but more efficient in motor applications, and large area uses. The higher voltages of 277/480v distribution systems are more<br />efficient, but considerably more dangerous, and should only be maintained and modified by trained and qualified electricians. The seemingly odd voltage relationships of 277/480, and 120/208, result from the timing of the individual output waveforms of the three transformers. In a single phase transformer that is center tapped and referenced to earth ground to produce a neutral, the line-to-neutral voltages are 180 degrees out of phase to each other. Therefore, the line-to-line voltage is exactly twice the line-to-neutral value. Since the line-to-neutral voltage waveforms of a three phase system are 120 degrees out of phase, they never cross the 0 voltage line at the same time. When two of the waveforms intersect above and below the 0 voltage line, they are at the exact same potential, and there is no voltage between them.<br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgqI5o8n7ZY0mn1q0p3pH-xTcLOftym0fy8nIxP5sfoXmu-nVTg_OoMdgdF0DU7EyjeGQl_Jp-cY5-2t02i_VTyFKKZqlzAu7TNencrfSUwgTslPVu5kgCEc6aZZfXuFwNqhddx7953UEI4/s1600-h/Copy+of+tr03.bmp"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgqI5o8n7ZY0mn1q0p3pH-xTcLOftym0fy8nIxP5sfoXmu-nVTg_OoMdgdF0DU7EyjeGQl_Jp-cY5-2t02i_VTyFKKZqlzAu7TNencrfSUwgTslPVu5kgCEc6aZZfXuFwNqhddx7953UEI4/s400/Copy+of+tr03.bmp" alt="" id="BLOGGER_PHOTO_ID_5210930905849088210" border="0" /></a>The B phase to C phase waveform shown in purple is a single phase, 208 volt relationship that exists in the output from the transformer on the previous page. The waveform produced by the relationship between A phase and C phase, is very similar to this one, except that it occurs 120 electrical degrees away. Likewise, the waveform for A phase and B phase makes up the third “leg” of this three phase, 208 volt transformer output.<br /><br />The common voltages that exist in the majority of large, commercial and industrial buildings in the United States are 277/480v, and 120/208v, (60hrz, or cycles per second). In parts of Canada and some European countries, the common voltage relationship is 220/380v, (50hrz). In each case, the mathematical relationship between voltages is the same; the larger number is 1.73 times the smaller number. This relationship is a math function derived from the fact that the waveforms are 120 electrical degrees apart. In the following diagram, the 120/208 could be replaced with 277/480, or 220/380. The change in frequency from 60hrz to 50hrz, simply changes the time it takes for each cycle of 360 electrical degrees to occur.<br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhwDPqwRX1QiZuR2X1ivAqiBIUuC21FYQFUmuTYk28KrV3_IbFMcJoNnxzgYL6Ef2l6nOLIKtzQlyZV-IHHV7yGbcluaL3zf-SV4ObFxIgvC3_j-vakvaeLehI-L1mOUTmpA_6GrrSQgjkq/s1600-h/tr04.bmp"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhwDPqwRX1QiZuR2X1ivAqiBIUuC21FYQFUmuTYk28KrV3_IbFMcJoNnxzgYL6Ef2l6nOLIKtzQlyZV-IHHV7yGbcluaL3zf-SV4ObFxIgvC3_j-vakvaeLehI-L1mOUTmpA_6GrrSQgjkq/s400/tr04.bmp" alt="" id="BLOGGER_PHOTO_ID_5210931333608202194" border="0" /></a>At 60hrz, voltage changes direction 120 a second, and at 50hrz, it changes 100 times a second.<br />This means that the magnetic field around the conductors of these AC circuits is constantly and rapidly changing. The higher the current the stronger the magnetic field. This constant change in magnetic flux consumes power and produces heat in what is called hysteresis loss. When the current and resulting magnetic fields are strong enough, conductors of other systems in close proximity, such as voice and data transfer circuits, can experience induced voltages that can cause errors and electrical noise.<br />Motors, lighting ballasts, and switching power supplies, (typical to computer equipment), all produce electrical characteristics that can distort the AC waveform. Electrical circuits and devices are always logical, but sometimes they can be unpredictable, and therefore dangerous, even to qualified electricians. The best tools are knowledge and understanding.<br /></div>tambarihttp://www.blogger.com/profile/00551341351972304033noreply@blogger.com2tag:blogger.com,1999:blog-1106722070395327999.post-55697411317715687482008-06-01T23:09:00.000-07:002008-06-02T22:46:52.527-07:00Ohm's Law<div style="text-align: justify;">For many conductors of electricity, the electric current which will flow through them is directly proportional to the voltage applied to them. When a microscopic view of Ohm's law is taken, it is found to depend upon the fact that the drift velocity of charges through the material is proportional to the electric field in the conductor. The ratio of voltage to current is called the resistance, and if the ratio is constant over a wide range of voltages, the material is said to be an "ohmic" material. If the material can be characterized by such a resistance, then the current can be predicted from the relationship:<br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjMh4s3oQSJ3dW-_Z5mzlxv2WpnJdiD4FYXw3fyoylxdXWqODzNhxocwFu_OeRI4BKsE7dm4tORGuT9OiiY1UpDfVj08zhcsdp92KoYEHYwx-R1QTVuoM2FbIpodhK8jEIevlbB1QHY58xe/s1600-h/ohmlaw.gif"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjMh4s3oQSJ3dW-_Z5mzlxv2WpnJdiD4FYXw3fyoylxdXWqODzNhxocwFu_OeRI4BKsE7dm4tORGuT9OiiY1UpDfVj08zhcsdp92KoYEHYwx-R1QTVuoM2FbIpodhK8jEIevlbB1QHY58xe/s400/ohmlaw.gif" alt="" id="BLOGGER_PHOTO_ID_5207163674046934626" border="0" /></a><span style="font-weight: bold;">The AC analog to Ohm's law is</span><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjhlUvNkoGOVifdorAJtVPeLLj3mlwTCnUJzjQJBY5rS35klex-4bL6qaYrunx40tqyJHiAdn28P95G2WgY9BTBLATlOAD1cLfYJVc141CDwAJr94Cg9qKVv23VFPtilW0YgmR4Ryd9pS35/s1600-h/acohm.gif"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjhlUvNkoGOVifdorAJtVPeLLj3mlwTCnUJzjQJBY5rS35klex-4bL6qaYrunx40tqyJHiAdn28P95G2WgY9BTBLATlOAD1cLfYJVc141CDwAJr94Cg9qKVv23VFPtilW0YgmR4Ryd9pS35/s400/acohm.gif" alt="" id="BLOGGER_PHOTO_ID_5207164072292754514" border="0" /></a>where Z is the impedance of the circuit and V and I are the rms or effective values of the voltage and current. Associated with the impedance Z is a phase angle, so that even though Z is the also the ratio of the voltage and current peaks, the peaks of voltage and current do not occur at the same time. The phase angle is necessary to characterize the circuit and allow the calculation of the average power used by the circuit.<br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg9v-pBKM4ezpje4euzL65SjboJx9IDUxPmIMoz_OQPkvTx1S1ygy3xhvTeZ_rdyICsqSbNQ5YvEwYDTfrX3Y8SX0ehKxgw74Het2gEsS5ZzxsCeufUOMpayKunV2JV5YMERbgZ4pvSjW6q/s1600-h/acohm2.gif"><img style="margin: 0pt 10px 10px 0pt; float: left; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg9v-pBKM4ezpje4euzL65SjboJx9IDUxPmIMoz_OQPkvTx1S1ygy3xhvTeZ_rdyICsqSbNQ5YvEwYDTfrX3Y8SX0ehKxgw74Het2gEsS5ZzxsCeufUOMpayKunV2JV5YMERbgZ4pvSjW6q/s400/acohm2.gif" alt="" id="BLOGGER_PHOTO_ID_5207193558845268882" border="0" /></a>If an rms voltage of Vrms =380<br />is applied to an impedance Z = 10 ohms,<br />then the rms current will be Irms = 38 A.<br />If the phase is φ = 3 degrees,<br />then the power factor is cosφ = 0.9986<br />and the average power is<br />Pavg = VrmsIrmscosφ = 14420.21 watts.<br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhRxFtat5gx3t6ECVvdX5gtvXjZ2ElapnhDj_yLex5MnT3v1KQxLcOxapIQ7U72_vPeJ9IdhJvvlvvAqDmfuPXA0flJTl7Pz2rYu_E11VI4pGY0SKQisQMeuISBskbEi02wxUNxtBBqgEJM/s1600-h/acohm3.gif"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhRxFtat5gx3t6ECVvdX5gtvXjZ2ElapnhDj_yLex5MnT3v1KQxLcOxapIQ7U72_vPeJ9IdhJvvlvvAqDmfuPXA0flJTl7Pz2rYu_E11VI4pGY0SKQisQMeuISBskbEi02wxUNxtBBqgEJM/s400/acohm3.gif" alt="" id="BLOGGER_PHOTO_ID_5207193720359417250" border="0" /></a>The illustration is for a case where the inductive reactance is dominant over the capacitive reactance as shown in the phasor diagram.<br /><br />Default values will be entered for V and Z above is they are left unspecified, but those values can be changed. If the current is changed, then Z will be recalculated. If a phase angle outside the allowed range -90 to +90 is entered, it will be replaced by a default value.<br /><br /><br /></div>tambarihttp://www.blogger.com/profile/00551341351972304033noreply@blogger.com0tag:blogger.com,1999:blog-1106722070395327999.post-27566435127133747842008-06-01T22:54:00.000-07:002008-06-01T22:57:58.286-07:00Electric current<div style="text-align: justify;"><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhigqWyvkuvy31gDhk3c2YJiMDVxXcrnb_IZCSiDt0Ga9IIiOY6M3UM725DIpsn9BO9kNPJwZZTMOAAhOv4jDVZbmPgV970i4yRNTWbGXMSsGninNlWYbYmFuPzRwen8OwivYkepnzSgVXj/s1600-h/ecur.gif"><img style="margin: 0pt 10px 10px 0pt; float: left; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhigqWyvkuvy31gDhk3c2YJiMDVxXcrnb_IZCSiDt0Ga9IIiOY6M3UM725DIpsn9BO9kNPJwZZTMOAAhOv4jDVZbmPgV970i4yRNTWbGXMSsGninNlWYbYmFuPzRwen8OwivYkepnzSgVXj/s400/ecur.gif" alt="" id="BLOGGER_PHOTO_ID_5207159280351212290" border="0" /></a>Electric current is the rate of charge flow past a given point in an electric circuit, measured in Coulombs/second which is named Amperes. In most DC electric circuits, it can be assumed that the resistance to current flow is a constant so that the current in the circuit is related to voltage and resistance by Ohm's law. The standard abbreviations for the units are 1 A = 1C/s.</div>tambarihttp://www.blogger.com/profile/00551341351972304033noreply@blogger.com0tag:blogger.com,1999:blog-1106722070395327999.post-22171924474868413172008-06-01T22:50:00.000-07:002008-06-25T23:05:16.308-07:00Y-Δ transformation<div style="text-align: justify;">The transformation is used to establish equivalence for networks with 3 terminals. Where three elements terminate at a common node and none are sources, the node is eliminated by transforming the impedances. For equivalence, the impedance between any pair of terminals must be the same for both networks. The equations given here are valid for real as well as complex impedances.<a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiREQR2O9dtr1t0BQEpbge4scEP65LGm7z3gJV3M52pHl68eKnHm4cpPqTAWIfu0En9fwkSTKdc-Ju8eVeHQ5rawbMcRmNpKhnzP4ooI01ReP-RaEZQ3u0wvl45Hnfl5P8_gGz1-50-zRpl/s1600-h/180px-Wye-delta.svg.png"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiREQR2O9dtr1t0BQEpbge4scEP65LGm7z3gJV3M52pHl68eKnHm4cpPqTAWIfu0En9fwkSTKdc-Ju8eVeHQ5rawbMcRmNpKhnzP4ooI01ReP-RaEZQ3u0wvl45Hnfl5P8_gGz1-50-zRpl/s400/180px-Wye-delta.svg.png" alt="" id="BLOGGER_PHOTO_ID_5216064748312780882" border="0" /></a><span style="font-weight: bold;">Equations for the transformation from Δ-load to Y-load 3-phase circuit</span><br /></div>The general idea is to compute the impedance Ry at a terminal node of the Y circuit with impedances R', R'' to adjacent nodes in the Δ circuit by<br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEggzeADhDVjk3c4vKB65bCEOjLf2gG4o1-pnVl6dvO68cN-B04y-7ZIXa5b8HLEf_40p1PRJ8ztN3ArJyJS_PcV9VKS9HKbLXPED_50C2hPXiq166bLvGXpVhXDo-L-XD0XEYxeEl4klg0z/s1600-h/ry.png"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEggzeADhDVjk3c4vKB65bCEOjLf2gG4o1-pnVl6dvO68cN-B04y-7ZIXa5b8HLEf_40p1PRJ8ztN3ArJyJS_PcV9VKS9HKbLXPED_50C2hPXiq166bLvGXpVhXDo-L-XD0XEYxeEl4klg0z/s400/ry.png" alt="" id="BLOGGER_PHOTO_ID_5216064672261281090" border="0" /></a>where RΔ are all impedances in the Δ circuit. This yields the specific formulae<br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjapBAhkyrLdejyI3ZAxQ2xRU1KV8HFsdcwYzUhnbeVUctB-F1EUi5-oCxBIGKeTCbLhaJbwqK2vesYafeOCKiqhpTl6kB7K-1M77Bl9oqEn6m1Y7SJhd2IxlwMplZldTB2p-pMHoSYUO0H/s1600-h/r123.png"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjapBAhkyrLdejyI3ZAxQ2xRU1KV8HFsdcwYzUhnbeVUctB-F1EUi5-oCxBIGKeTCbLhaJbwqK2vesYafeOCKiqhpTl6kB7K-1M77Bl9oqEn6m1Y7SJhd2IxlwMplZldTB2p-pMHoSYUO0H/s400/r123.png" alt="" id="BLOGGER_PHOTO_ID_5216064844731022834" border="0" /></a><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEibfd4weSDLlaUZAKTEIb5EbQU92vMsD2IJug7shBYyS9r9MYug7qFwCDdr07dUv_ShEcyjNBBBFMdYrvLRcZI32zGO9m5vstUliSA3lg-YMxjAZpN-TIgo3fMp47rrEfFi1VEhRPbmu8aX/s1600-h/r2.png"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEibfd4weSDLlaUZAKTEIb5EbQU92vMsD2IJug7shBYyS9r9MYug7qFwCDdr07dUv_ShEcyjNBBBFMdYrvLRcZI32zGO9m5vstUliSA3lg-YMxjAZpN-TIgo3fMp47rrEfFi1VEhRPbmu8aX/s400/r2.png" alt="" id="BLOGGER_PHOTO_ID_5216065511798511410" border="0" /></a><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhOXO1AAlZo7xxOlDmCj1s9q8BsFfsBNK1R6ofCmtI0EztH4_V2sHDWRAprRH3CCaBMJYCymdA3gGYP8ZZoW9hjVn6LXmPZG6kHPlDq5ecw0zzKVtjGLRd_SsC4n3vs8kh8cVElpXRGxDEh/s1600-h/r3.png"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhOXO1AAlZo7xxOlDmCj1s9q8BsFfsBNK1R6ofCmtI0EztH4_V2sHDWRAprRH3CCaBMJYCymdA3gGYP8ZZoW9hjVn6LXmPZG6kHPlDq5ecw0zzKVtjGLRd_SsC4n3vs8kh8cVElpXRGxDEh/s400/r3.png" alt="" id="BLOGGER_PHOTO_ID_5216065707074126434" border="0" /></a><span style="font-weight: bold;">Equations for the transformation from Y-load to Δ-load 3-phase circuit</span><br /><br />The general idea is to compute an impedance RΔ in the Δ circuit by<br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgLbNmeeha1eNV_QNibkd0Oeg7Y_KlZ1vz-hyUTdshb1-D48z6qWUhkBnJaoHlYd4YRQvM7t_5s1DrlD_pkgZyNS3tAWzoBAWOGZrfailXsRBPkExSpsqNC4EzY2mb5rJrfZLAt6qyfYyl3/s1600-h/rp.png"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgLbNmeeha1eNV_QNibkd0Oeg7Y_KlZ1vz-hyUTdshb1-D48z6qWUhkBnJaoHlYd4YRQvM7t_5s1DrlD_pkgZyNS3tAWzoBAWOGZrfailXsRBPkExSpsqNC4EzY2mb5rJrfZLAt6qyfYyl3/s400/rp.png" alt="" id="BLOGGER_PHOTO_ID_5216064582475273090" border="0" /></a>where RP = R1R2 + R2R3 + R3R1 is the sum of the products of all pairs of impedances in the Y circuit and Ropposite is the impedance of the node in the Y circuit which is opposite the edge with RΔ. The formulae for the individual edges are thus<br /><br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiT3vSBh5sIWj8wPimycXrHRQPDcF5XXfO_jMRVNQPcpuAbLkhIyv_vzx-UlxfsDNK8b62X4yzoExNyZaBLaBKGoMW73UxS5rMbc6ZnkhPKcu1QUPgQiNZaAjbvdLpAw_euIAQ6n99KlIwZ/s1600-h/rabc.png"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiT3vSBh5sIWj8wPimycXrHRQPDcF5XXfO_jMRVNQPcpuAbLkhIyv_vzx-UlxfsDNK8b62X4yzoExNyZaBLaBKGoMW73UxS5rMbc6ZnkhPKcu1QUPgQiNZaAjbvdLpAw_euIAQ6n99KlIwZ/s400/rabc.png" alt="" id="BLOGGER_PHOTO_ID_5216064947458136402" border="0" /></a><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjHqEUqLDO8yux7A3-tYlyyP7Q05Sej14D4WcYN5mc20-doUvHemglSTGtONSa2XeiajAAZJtt9YVZO5P5jutIcrpaZSkVJfaZanGMJVSOaaCE6Js28qDXBzZeKwOc0PDsKyGkvZxHY-582/s1600-h/rb.png"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjHqEUqLDO8yux7A3-tYlyyP7Q05Sej14D4WcYN5mc20-doUvHemglSTGtONSa2XeiajAAZJtt9YVZO5P5jutIcrpaZSkVJfaZanGMJVSOaaCE6Js28qDXBzZeKwOc0PDsKyGkvZxHY-582/s400/rb.png" alt="" id="BLOGGER_PHOTO_ID_5216066634593511842" border="0" /></a><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEizcUo0AR08FAsTeMcrFwHHaWc9J_Mdqq-YJpbqga-vH9PDbzDanOtgj3m8RA_9yStCKDEunWO8OtDiE9FdZ0wji23BJUg__XUwGUrCy9BeOjULkQMDJeQfuNNtWUuGlP-c1GGb5vi5krwZ/s1600-h/rc.png"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEizcUo0AR08FAsTeMcrFwHHaWc9J_Mdqq-YJpbqga-vH9PDbzDanOtgj3m8RA_9yStCKDEunWO8OtDiE9FdZ0wji23BJUg__XUwGUrCy9BeOjULkQMDJeQfuNNtWUuGlP-c1GGb5vi5krwZ/s400/rc.png" alt="" id="BLOGGER_PHOTO_ID_5216066736609904914" border="0" /></a>tambarihttp://www.blogger.com/profile/00551341351972304033noreply@blogger.com1tag:blogger.com,1999:blog-1106722070395327999.post-51625643636041286722008-05-30T21:39:00.000-07:002008-06-02T21:42:33.363-07:00Moving Coil MetersThe design of a voltmeter, ammeter or ohmmeter begins with a current-sensitive element. Though most modern meters have solid state digital readouts, the physics is more readily demonstrated with a moving coil current detector called a galvanometer. Since the modifications of the current sensor are compact, it is practical to have all three functions in a single instrument with multiple ranges of sensitivity. Schematically, a single range "multimeter" might be designed as illustrated.<br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjyv1mOxpTspcufKw7VxyNytoda46_Go1TKA9Q3trfjaGgyE-idtJV3uXMU23ngUTBDUawvwOzJrqeH90y4Nn4jOdAF8E9V9BIDY-csyxpCaGWFCY1hEjEuMdzDtlanITcAJHZF-tZAYlFa/s1600-h/mmet.gif"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjyv1mOxpTspcufKw7VxyNytoda46_Go1TKA9Q3trfjaGgyE-idtJV3uXMU23ngUTBDUawvwOzJrqeH90y4Nn4jOdAF8E9V9BIDY-csyxpCaGWFCY1hEjEuMdzDtlanITcAJHZF-tZAYlFa/s400/mmet.gif" alt="" id="BLOGGER_PHOTO_ID_5207510583468296546" border="0" /></a>tambarihttp://www.blogger.com/profile/00551341351972304033noreply@blogger.com0tag:blogger.com,1999:blog-1106722070395327999.post-44603459584848894512008-05-29T07:02:00.001-07:002008-05-29T18:21:35.026-07:00Electrical Motor Efficiency<p style="text-align: justify;">Electrical motor efficiency is the ratio between the shaft output power - and the electrical input power.<br /><span style="font-weight: bold;">Electrical Motor Efficiency when Shaft Output is measured in Watt</span> </p><p style="text-align: justify;">If the power output is measured in Watt (W), efficiency can be expressed as: </p><p style="text-align: justify;"> ηm = Pout / Pin (1) </p><p style="text-align: justify;"> where </p><p style="text-align: justify;"> ηm = motor efficiency </p><p style="text-align: justify;"> Pout = shaft power out (Watt, W) </p><p style="text-align: justify;"> Pin = electric power in to the motor (Watt, W) </p><p style="text-align: justify;"><span style="font-weight: bold;">Electrical Motor Efficiency when Shaft Output is measured in Horsepower</span> </p><p style="text-align: justify;">If the power out is measured in horsepower (hp), efficiency can be expressed as: </p><p style="text-align: justify;"> ηm = Pout 746 / Pin (2) </p><p style="text-align: justify;"> where </p><p style="text-align: justify;"> Pout = shaft power out (horsepower, hp) </p><p style="text-align: justify;"> Pin = electric power in to the motor (Watt, W) </p><p style="text-align: justify;"><span style="font-weight: bold;">Primary and Secondary Resistance Losses</span> </p><p style="text-align: justify;">The electrical power lost in the primary rotor and secondary stator winding resistance are also called the copper losses. The copper loss vary with the load in proportion to the current squared and can be expressed as </p><p style="text-align: justify;"> Pcl = R I2 (3) </p><p style="text-align: justify;"> where </p><p style="text-align: justify;"> Pcl = stator winding - copper loss (W) </p><p style="text-align: justify;"> R = resistance (Ω) </p><p style="text-align: justify;"> I = current (Amp) </p><p style="text-align: justify;"><span style="font-weight: bold;">Iron Losses</span> </p><p style="text-align: justify;">These losses are the result of magnetic energy dissipated when when the motors magnetic field is applied to the stator core.</p><p style="text-align: justify;"><span style="font-weight: bold;">Stray Losses</span> </p><p style="text-align: justify;">Stray losses are the losses that remains after primary copper and secondary losses, iron losses and mechanical losses. The largest contribution to the stray losses is harmonic energies generated when the motor operates under load. These energies are dissipated as currents in the copper windings, harmonic flux components in the iron parts, leakage in the laminate core.</p><p style="text-align: justify;"><span style="font-weight: bold;">Mechanical Losses</span> </p><p style="text-align: justify;">Mechanical losses includes friction in the motor bearings and the fan for air cooling.</p><p style="text-align: justify;">NEMA Design B Electrical Motors </p><p style="text-align: justify;">Electrical motors constructed according NEMA Design B must meet the efficiencies below</p><div style="text-align: justify;"> </div><table style="text-align: left; margin-left: 0px; margin-right: 0px;" border="1" cellpadding="2" cellspacing="0" width="431"> <tbody> <tr> <td valign="top" width="208"> <p align="center">Power (hp)</p></td> <td valign="top" width="221"> <p align="center">Minimum nominal efficiency *</p></td></tr> <tr> <td valign="top" width="208"> <p align="center">1-4</p></td> <td valign="top" width="221"> <p align="center">78.8</p></td></tr> <tr> <td valign="top" width="208"> <p align="center">5-9</p></td> <td valign="top" width="221"> <p align="center">84.0</p></td></tr> <tr> <td valign="top" width="208"> <p align="center">10-19</p></td> <td valign="top" width="221"> <p align="center">85.5</p></td></tr> <tr> <td valign="top" width="208"> <p align="center">20-49</p></td> <td valign="top" width="221"> <p align="center">88.5</p></td></tr> <tr> <td valign="top" width="208"> <p align="center">50-99</p></td> <td valign="top" width="221"> <p align="center">90.2</p></td></tr> <tr> <td valign="top" width="208"> <p align="center">100-124</p></td> <td valign="top" width="221"> <p align="center">91.7</p></td></tr> <tr> <td valign="top" width="208"> <p align="center">>125</p></td> <td valign="top" width="221"> <p align="center">92.4</p></td></tr></tbody></table><div style="text-align: justify;"> </div><p style="text-align: justify;">*NEMA Design B, Single Speed 1200, 1800, 3600 RPM. Open Drip Proof (ODP) or Totally Enclosed Fan Cooled (TEFC) motors 1 hp and larger that operate more than 500 hours per year.</p>tambarihttp://www.blogger.com/profile/00551341351972304033noreply@blogger.com0tag:blogger.com,1999:blog-1106722070395327999.post-66600435534453451562008-05-29T06:41:00.000-07:002008-05-29T06:47:23.505-07:00power factor for a three phase electrical motor<div style="text-align: justify;">The power factor of an AC electric power system is defined as the ratio of the active (true or real) power to the apparent power.<br /></div><ul style="text-align: justify;"><li>Active (Real or True) Power is measured in watts (W) and is the power drawn by the electrical resistance of a system that does useful work.</li><li> Apparent Power is measured in volt-amperes (VA) and is the voltage on an AC system multiplied by all the current that flows in it. It is the vector sum of the true and the reactive power.<br /></li></ul><div style="text-align: justify;">The third component of the AC power flow, the<br /></div><ul style="text-align: justify;"><li>Reactive Power, is measured in volt-amperes reactive (VAR). Reactive Power is the power stored in and discharged by the inductive motors, transformers or solenoids.</li></ul><div style="text-align: justify;">The reactive power required by an inductive load will increase the amount of apparent power - measured in kilovolt amps (kVA) - in the distribution system. Increasing the reactive and apparent power will cause the power factor - PF - to decrease.<br /><br /><span style="font-weight: bold;">Power Factor</span><br />It is common to define the Power Factor - PF - as the cosine of the phase angle between voltage and current - or the "cosφ". The power factor defined by IEEE and IEC is the ratio between the applied true power - and the apparent power, and can in general be expressed as:<br /><br /> PF = Wactive / Wapparent (1)<br /><br /> where<br /><br /> PF = power factor<br /> Wactive = active (true or real) power (Watt)<br /> Wapparent = apparent power (VA, volts amps)<br /><br />A low power factor is the result of inductive loads such as transformers and electric motors. Unlike resistive loads creating heat by consuming kilowatts, inductive loads require a current flow to create magnetic fields to produce the desired work.<br /><br />Power factor is an important measurement in electrical AC systems because<br /></div><ul style="text-align: justify;"><li>an overall power factor less than 1 indicates that the electricity supplier need to provide more generating capacity than actually required</li><li>the current waveform distortion that contributes to reduced power factor is caused by voltage waveform distortion and overheating in the neutral cables of three-phase systems<br /></li></ul><div style="text-align: justify;">International standards such as IEC 61000-3-2 have been established to control current waveform distortion by introducing limits for the amplitude of current harmonics.<br /><br /><span style="font-weight: bold;">Example - Power Factor</span><br />A industrial plant draws 200 A at 400 V and the supply transformer and backup UPS is rated 200 A × 400 V = 80 kVA.<br /><br />If the power factor - PF - of the loads is only 0.7 - only 80 kVA × 0.7 = 56 kVA of real power is consumed by the system. If the power factor was close to 1, the supply system with transformers, cables, switchgear and UPS could have been done considerably smaller.<br /><br />A low power factor is expensive and inefficient and some utility companies may charge additional fees when the power factor is less than 0.95. A low power factor will reduce the electrical system's distribution capacity by increasing the current flow and causing voltage drops.<br /><br /><span style="font-weight: bold;">Power Factor for a Three-Phase Motor</span><br />The total power required by an inductive device as a motor or similar consists of<br /></div><ul style="text-align: justify;"><li>Active (true or real) power (measured in kilowatts, kW)</li><li>Reactive power - the nonworking power caused by the magnetizing current, required to operate the device (measured in kilovars, kVAR)<br /></li></ul><div style="text-align: justify;">The power factor for a three-phase electric motor can be expressed as:<br /><br /> PF = Wapplied / [(3)1/2 U I] (2)<br /><br /> where<br /><br /> PF = power factor<br /> Wapplied = power applied (W, watts)<br /> U = voltage (V)<br /> I = current (A, amps)<br /><br /></div>tambarihttp://www.blogger.com/profile/00551341351972304033noreply@blogger.com1tag:blogger.com,1999:blog-1106722070395327999.post-50149872175102918922008-05-29T06:31:00.001-07:002008-05-29T06:38:11.967-07:00electric formulas<p>Common electrical units used in formulas and equations are: </p> <ul> <li>Volts - The units of electrical potential or motive force. The force is required to send one ampere of current through one ohm of resistance. </li><li>Ohms - The units of resistance. One ohm is the resistance offered to the passage of one ampere when impelled by one volt. </li><li>Amperes - The units of current. One ampere is the current which one volt can send through a resistance of one ohm. </li><li>Watts - The unit of electrical energy or power. One watt is the product of one ampere and one volt. One ampere of current flowing under the force of one volt gives one watt of energy. </li><li>Volt Amperes - The product of the volts and amperes as shown by a voltmeter and ammeter. In direct current systems, volt ampere is the same as watts or the energy delivered. In alternating current systems, the volts and amperes may or may not be 100% synchronous. When synchronous, the volt amperes equal the watts on a wattmeter. When not synchronous, volt amperes exceed watts. More about reactive power. </li><li>Kilovolt Ampere - One kilovolt ampere - KVA - is equal to 1,000 volt amperes. </li><li>Power Factor - is the ratio of watts to volt amperes. </li></ul> <p style="font-weight: bold;">Electric Power Formulas</p><p> W = E I (1a)<br /> W = R I2 (1b)<br /> W = E2/ R (1c)</p><p> where</p><p> W = power (Watts)<br /> E = voltage (Volts)<br /> I = current (Amperes)<br /> R = resistance (Ohms)</p><p><span style="font-weight: bold;">Electric Current Formulas</span> </p><p> I = E / R (2a)<br /> I = W / E (2b)<br /> I = (W / R)1/2 (2c) </p><p><span style="font-weight: bold;">Electric Resistance Formulas</span> </p><p> R = E / I (3a)<br /> R = E2/ W (3b)<br /> R = W / I2 (3c) </p><p><span style="font-weight: bold;">Electrical Potential Formulas - Ohms Law</span> </p><p>Ohms law can be expressed as: </p><p> E = R I (4a)<br /> E = W / I (4b)<br /> E = (W R)1/2 (4c) </p><p><span style="font-weight: bold;">Example - Ohm's law</span> </p><p>A 12 volt battery supplies power to a resistance of 18 ohms. </p><p> I = (12 Volts) / (18 ohms)<br /> = 0.67 Ampere </p><p><span style="font-weight: bold;">Electrical Motor Formulas</span><br /><span style="font-weight: bold;">Electrical Motor Efficiency</span> </p><p> μ = 746 Php / Winput (5) </p><p> where </p><p> μ = efficiency<br /> Php = output horsepower (hp)<br /> Winput = input electrical power (Watts) </p><p>or alternatively </p><p> μ = 746 Php / (1.732 E I PF) (5b) </p><p><span style="font-weight: bold;">Electrical Motor - Power</span> </p><p> W3-phase = (E I PF 1.732) / 1,000 (6) </p><p> where </p><p> W3-phase = electrical power 3-phase motor (kW)<br /> PF = power factor electrical motor </p><p><span style="font-weight: bold;">Electrical Motor - Amps</span> </p><p> I3-phase = (746 Php) / (1.732 E μ PF) (7) </p><p> where </p><p> I3-phase = electrical current 3-phase motor (Amps)<br /> PF = power factor electrical motor</p>tambarihttp://www.blogger.com/profile/00551341351972304033noreply@blogger.com0tag:blogger.com,1999:blog-1106722070395327999.post-25475800737151214222008-05-27T21:51:00.000-07:002008-06-02T21:53:11.793-07:00The value of electrical resistance associated with a circuit element or appliance can be determined by measuring the voltage across it with a voltmeter and the current through it with an ammeter and then dividing the measured voltage by the current. This is an application of Ohm's law, but this method works even for non-ohmic resistances where the resistance might depend upon the current. At least in those cases it gives you the effective resistance in ohms under that specific combination of voltage and current.<br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiM7-5nVIg5HYUNRK4sM18RsJ2aWnKnCxXpi2aPYYC2qtcuePwfAXBsHqwHQIPmGitd02tHrDwfzqHclnZ6myEmNTU5MR3Vun_gsfdrTcpjeG9FsiDWEAHN2YcqpxQdtEqrbxvigjcra8wR/s1600-h/resvi.gif"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiM7-5nVIg5HYUNRK4sM18RsJ2aWnKnCxXpi2aPYYC2qtcuePwfAXBsHqwHQIPmGitd02tHrDwfzqHclnZ6myEmNTU5MR3Vun_gsfdrTcpjeG9FsiDWEAHN2YcqpxQdtEqrbxvigjcra8wR/s400/resvi.gif" alt="" id="BLOGGER_PHOTO_ID_5207513552109654738" border="0" /></a>tambarihttp://www.blogger.com/profile/00551341351972304033noreply@blogger.com0tag:blogger.com,1999:blog-1106722070395327999.post-5066785728614516582008-05-27T19:16:00.000-07:002008-06-02T19:32:49.259-07:00Conductors and Insulators<a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjZ8IpviNvwQf2bpRDRiaW1wGQbtAW_HO5jp7iBBe_zFojGXPHzveheC_e1K16LvOv5Tu2rFkKIDfg5FIdLkGs4-hoS1v3b7gKqGTMnz-fFzSDj4ZMpu26aSj2xurw1RE2zmtMUQNSMMtn6/s1600-h/cond.gif"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjZ8IpviNvwQf2bpRDRiaW1wGQbtAW_HO5jp7iBBe_zFojGXPHzveheC_e1K16LvOv5Tu2rFkKIDfg5FIdLkGs4-hoS1v3b7gKqGTMnz-fFzSDj4ZMpu26aSj2xurw1RE2zmtMUQNSMMtn6/s400/cond.gif" alt="" id="BLOGGER_PHOTO_ID_5207477472920937602" border="0" /></a><span style="font-weight: bold;">Conductors</span><br /><p align="justify"><strong></strong>In a conductor, electric current can flow freely, in an insulator it cannot. Metals such as copper typify conductors, while most non-metallic solids are said to be good insulators, having extremely high resistance to the flow of charge through them. "Conductor" implies that the outer electrons of the atoms are loosely bound and free to move through the material. Most atoms hold on to their electrons tightly and are insulators. In copper, the valence electrons are essentially free and strongly repel each other. Any external influence which moves one of them will cause a repulsion of other electrons which propagates, "domino fashion" through the conductor. </p> <p align="justify">Simply stated, most metals are good electrical conductors, most nonmetals are not. Metals are also generally good heat conductors while nonmetals are not. </p><p align="justify"><strong>Insulators </strong> </p><p align="justify">Most solid materials are classified as insulators because they offer very large resistance to the flow of electric current. Metals are classified as conductors because their outer electrons are not tightly bound, but in most materials even the outermost electrons are so tightly bound that there is essentially zero electron flow through them with ordinary voltages. Some materials are particularly good insulators and can be characterized by their high resistivities: </p><p align="justify"> </p> <table border="1" cellpadding="1" cellspacing="0" width="400"> <tbody> <tr> <td valign="top" width="200"> <p align="center">materials</p></td> <td valign="top" width="200"> <p align="center">Resistivity (ohm m)</p></td></tr> <tr> <td valign="top" width="200">Glass </td> <td valign="top" width="200"> <p align="center">10<sup>12</sup></p></td></tr> <tr> <td valign="top" width="200">Mica </td> <td valign="top" width="200"> <p align="center">9 x 10<sup>13</sup></p></td></tr> <tr> <td valign="top" width="200">Quartz (fused) </td> <td valign="top" width="200"> <p align="center">5 x 10<sup>16</sup></p></td></tr></tbody></table> <p>This is compared to the resistivity of copper:</p> <table border="1" cellpadding="1" cellspacing="0" width="400"> <tbody> <tr> <td valign="top" width="200"> <p align="center">materials</p></td> <td valign="top" width="200"> <p align="center">Resistivity (ohm m)</p></td></tr> <tr> <td valign="top" width="200">Copper</td> <td valign="top" width="200"> <p align="center">1.7 x 10<sup>-8</sup></p></td></tr></tbody></table>tambarihttp://www.blogger.com/profile/00551341351972304033noreply@blogger.com0tag:blogger.com,1999:blog-1106722070395327999.post-74221403335456637892008-05-27T18:31:00.000-07:002008-06-02T18:51:07.347-07:00Current Law<div style="text-align: justify;">The electric current in amperes which flows into any junction in an electric circuit is equal to the current which flows out. This can be seen to be just a statement of conservation of charge. Since you do not lose any charge during the flow process around the circuit, the total current in any cross-section of the circuit is the same. Along with the voltage law, this law is a powerful tool for the analysis of electric circuits.<br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjFzJmxXr_4HNSARsOW8o24U1ahQb9_3twxWMiR6wU6S2JyY3nvci6yfeu6S5jH6tB54MzupEDC2Z5CbAzUZiay4iD9x5ZtOaLjuWTLqgZscltPejSIueUwXhBeAlSSehKYBELGATAAPRYr/s1600-h/curlaw.gif"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjFzJmxXr_4HNSARsOW8o24U1ahQb9_3twxWMiR6wU6S2JyY3nvci6yfeu6S5jH6tB54MzupEDC2Z5CbAzUZiay4iD9x5ZtOaLjuWTLqgZscltPejSIueUwXhBeAlSSehKYBELGATAAPRYr/s400/curlaw.gif" alt="" id="BLOGGER_PHOTO_ID_5207462414871853874" border="0" /></a>The current law is one of the main tools for the analysis of electric circuits, along with Ohm's Law, the voltage law and the power relationship. Applying the current law to the above circuits along with Ohm's law and the rules for combining resistors gives the numbers shown below. The determining of the voltages and currents associated with a particular circuit along with the power allows you to completely describe the electrical state of a direct current circuit.<br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi-wM-RF9tZwXqJs8kZ59_AYcU1TWcZHmkK-cdMS4OlOI9l3oqU29RAYE5kfT4vpASG8F8cpCaaTXFoL3uxS9FEUKZT0noYQsIP-LfSIt6qeGQLTFb6lbI_BJhGfmbxNrSw-H35rz54d7Qj/s1600-h/curlawa.gif"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi-wM-RF9tZwXqJs8kZ59_AYcU1TWcZHmkK-cdMS4OlOI9l3oqU29RAYE5kfT4vpASG8F8cpCaaTXFoL3uxS9FEUKZT0noYQsIP-LfSIt6qeGQLTFb6lbI_BJhGfmbxNrSw-H35rz54d7Qj/s400/curlawa.gif" alt="" id="BLOGGER_PHOTO_ID_5207462517881092626" border="0" /></a></div>tambarihttp://www.blogger.com/profile/00551341351972304033noreply@blogger.com0tag:blogger.com,1999:blog-1106722070395327999.post-8932048643345974542008-05-25T22:40:00.000-07:002008-06-25T22:46:22.157-07:00ac three phases<a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhZ-h_qhsfNiMw-iwHrm1HEAngy89mrEaLvr3Bp7_ZA6eqoRckVA1jb_ctPbANMfpSNp9seTvx3Ynbpo5Q2Oxdil-mq1cenGLdNgprAFvb3utfbWuUfY4etJDmffS42Yd0k74vZ6mSMy-BF/s1600-h/ac.gif"><img style="margin: 0pt 10px 10px 0pt; float: left; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhZ-h_qhsfNiMw-iwHrm1HEAngy89mrEaLvr3Bp7_ZA6eqoRckVA1jb_ctPbANMfpSNp9seTvx3Ynbpo5Q2Oxdil-mq1cenGLdNgprAFvb3utfbWuUfY4etJDmffS42Yd0k74vZ6mSMy-BF/s400/ac.gif" alt="" id="BLOGGER_PHOTO_ID_5216061690999951970" border="0" /></a>Three-phase, abbreviated 3φ, refers to three voltages or currents that that differ by a third of a cycle, or 120 electrical degrees, from each other. They go through their maxima in a regular order, called the phase sequence. The three phases could be supplied over six wires, with two wires reserved for the exclusive use of each phase. However, they are generally supplied over only three wires, and the phase or line voltages are the voltages between the three possible pairs of wires. The phase or line currents are the currents in each wire. Voltages and currents are usually expressed as rms or effective values, as in single-phase analysis.<br /><div style="text-align: justify;"><br />When you connect a load to the three wires, it should be done in such a way that it does not destroy the symmetry. This means that you need three equal loads connected across the three pairs of wires. This looks like an equilateral triangle, or delta, and is called a delta load. Another symmetrical connection would result if you connected one side of each load together, and then the three other ends to the three wires. This looks like a Y, and is called a wye load. These are the only possibilities for a symmetrical load. The center of the Y connection is, in a way, equidistant from each of the three line voltages, and will remain at a constant potential. It is called the neutral, and may be furnished along with the three phase voltages. The benefits of three-phase are realized best for such a symmetrical connection, which is called balanced. If the load is not balanced, the problem is a complicated one one whose solution gives little insight, just numbers. Such problems are best left to computer circuit analysis. Three-phase systems that are roughly balanced (the practical case) can be analyzed profitably by a method called symmetrical components. Here, let us consider only balanced three-phase circuits, which are the most important anyway.<br /><br />The key to understanding three-phase is to understand the phasor diagram for the voltages or currents. In the diagram at the right, a, b and c represent the three lines, and o represents the neutral. The red phasors are the line or delta voltages, the voltages between the wires. The blue phasors are the wye voltages, the voltages to neutral. They correspond to the two different ways a symmetrical load can be connected. The vectors can be imagined rotating anticlockwise with time with angular velocity ω = 2πf, their projections on the horizontal axis representing the voltages as functions of time. Note how the subscripts on the V's give the points between which the voltage is measured, and the sign of the voltage. Vab is the voltage at point a relative to point b, for example. The same phasor diagram holds for the currents. In this case, the line currents are the blue vectors, and the red vectors are the currents through a delta load. The blue and red vectors differ in phase by 30°, and in magnitude by a factor of √3, as is marked in the diagram.<br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjqdOJecDapflH-eSSn5O9J0RBclLfLtK5itE9G6NVeZDYv1oemM6vIr76EpKgFJ5EKVYgUwJ3EpOE5BzF3sdQ2lIv3yDVGuMEremCQVLOUhftNZSUt8hLFDWIal31DVaOMCMBtbgzEyYYG/s1600-h/volt+3ph.bmp.jpg"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjqdOJecDapflH-eSSn5O9J0RBclLfLtK5itE9G6NVeZDYv1oemM6vIr76EpKgFJ5EKVYgUwJ3EpOE5BzF3sdQ2lIv3yDVGuMEremCQVLOUhftNZSUt8hLFDWIal31DVaOMCMBtbgzEyYYG/s400/volt+3ph.bmp.jpg" alt="" id="BLOGGER_PHOTO_ID_5216061914472052706" border="0" /></a>where Vph is the phase voltage.<br />In Y(Star) connected system VLine = √3 VPhase , ILine = IPhase .<br />In Delta connected system VLine = VPhase , ILine = √3 IPhase<br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgKcihuaHKsxqa5hrUmFD-zIqBhcsYNRSWSWsLIuTVrWc-p1g21D2k5mQej6X_bl66gfhNz6Fd78tsg5Q-aHhuDg-qXJ7QOLpOZK06_Ml2pb_JIUvqIddR8dm9YAHzuuOjBsnWcEqhV0nC_/s1600-h/ac+3ase.gif.png"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgKcihuaHKsxqa5hrUmFD-zIqBhcsYNRSWSWsLIuTVrWc-p1g21D2k5mQej6X_bl66gfhNz6Fd78tsg5Q-aHhuDg-qXJ7QOLpOZK06_Ml2pb_JIUvqIddR8dm9YAHzuuOjBsnWcEqhV0nC_/s400/ac+3ase.gif.png" alt="" id="BLOGGER_PHOTO_ID_5216061802527224690" border="0" /></a>The above figure sows the one voltage cycle of a three - phase system .The three colours represent 3 phase voltages displaced by 120 electrical degrees.In the figure Phase 'a' in black , phase 'b' in red ,phase 'c' in blue colour are represented.</div>tambarihttp://www.blogger.com/profile/00551341351972304033noreply@blogger.com0tag:blogger.com,1999:blog-1106722070395327999.post-21848345128239580852008-05-25T22:34:00.000-07:002008-06-25T22:35:55.800-07:00transmission lines<div style="text-align: justify;">Transmission lines are classified as short, medium and long. When the length of the line is less than about 80Km the effect of shunt capacitance and conductance is neglected and the line is designated as a short transmission line. For these lines the operating voltage is less than 20KV.<br /><br />For medium transmission lines the length of the line is in between 80km - 240km and the operating line voltage wil be in between 21KV-100KV.In this case the shunt capacitance can be assumed to be lumped at the middle of the line or half of the shunt capacitance may be considered to be lumped each end of the line.The two representations of medium length lines are termed as nominal-T and nominal- π respectively.<br /><br />Lines more than 240Km long and line voltage above 100KV require calculations in terms of distributed parameters.Such lines are known as long transmission lines.This classification on the basis of length is more or less arbitrary and the real criterion is the degree of accuracy required.</div>tambarihttp://www.blogger.com/profile/00551341351972304033noreply@blogger.com0tag:blogger.com,1999:blog-1106722070395327999.post-72101827455755321872008-05-25T19:49:00.000-07:002008-06-02T19:57:20.209-07:00Capacitors<a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiimG6inZ30qtqlyu1S9_4T4Y3H0oGanYrwUe42ZfRIm2a3dqBMknxc_VR8jjEFkxoMbJJdCt2mo6XA4mWDSLCIoQrIejPflUOW1nWxITd0zdlSfALOM5h0JqM_cJ-KtG2AqPhXz65U324w/s1600-h/cap.gif"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiimG6inZ30qtqlyu1S9_4T4Y3H0oGanYrwUe42ZfRIm2a3dqBMknxc_VR8jjEFkxoMbJJdCt2mo6XA4mWDSLCIoQrIejPflUOW1nWxITd0zdlSfALOM5h0JqM_cJ-KtG2AqPhXz65U324w/s400/cap.gif" alt="" id="BLOGGER_PHOTO_ID_5207482340997572578" border="0" /></a>Capacitance is typified by a parallel plate arrangement and is defined in terms of charge storage: <p>where </p><p> * Q = magnitude of charge stored on each plate.<br />* V = voltage applied to the plates. </p><p><strong>Capacitor Combinations</strong> </p><p>Capacitors in parallel add ... </p><p><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjmq2WFSUxO13AsU43DHwBf2c8WCxYl2DoPGmb6LAAHEfVJkwZub-tbT1cZ00InPOxJowi9SexJSLbqaBwGt9pMzzCFrHHwCOKTvauF8sJHXbNqfBItHjMWcIaMQ5-UamfdplVWdbVkQB3F/s1600-h/capcom.gif"><img style="margin: 0pt 10px 10px 0pt; float: left; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjmq2WFSUxO13AsU43DHwBf2c8WCxYl2DoPGmb6LAAHEfVJkwZub-tbT1cZ00InPOxJowi9SexJSLbqaBwGt9pMzzCFrHHwCOKTvauF8sJHXbNqfBItHjMWcIaMQ5-UamfdplVWdbVkQB3F/s400/capcom.gif" alt="" id="BLOGGER_PHOTO_ID_5207482710608210034" border="0" /></a>If <img src="http://hyperphysics.phy-astr.gsu.edu/hbase/electric/imgele/c1.gif" /> = <span style="font-size:130%;">50</span> <img src="http://hyperphysics.phy-astr.gsu.edu/hbase/electric/imgele/mf.gif" />,<img src="http://hyperphysics.phy-astr.gsu.edu/hbase/electric/imgele/c2.gif" />= <span style="font-size:130%;">20</span><img src="http://hyperphysics.phy-astr.gsu.edu/hbase/electric/imgele/mf.gif" /> </p> <p>then</p><p> </p><p><strike><img src="http://hyperphysics.phy-astr.gsu.edu/hbase/electric/imgele/ceq.gif" /></strike>=<span style="font-weight: bold;">C1 + C2 = 70</span> <img src="http://hyperphysics.phy-astr.gsu.edu/hbase/electric/imgele/mf.gif" /></p> <p>Capacitors in series combine as reciprocals ...</p><p><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEidzqWYedPiWe0dnf4lYRSUCdqE3c8xwswugLCVn-Uq7mUcPtZSyi4Cqlz_5CxG5kUsPfM9DWi1L3-J7GNWgg0qUVwlpNEMmj-WHv2V9xfk2aRf7yB2-yX973XQ3JM0VUCnM8_rS-GZqhbl/s1600-h/capcom2.gif"><img style="margin: 0pt 10px 10px 0pt; float: left; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEidzqWYedPiWe0dnf4lYRSUCdqE3c8xwswugLCVn-Uq7mUcPtZSyi4Cqlz_5CxG5kUsPfM9DWi1L3-J7GNWgg0qUVwlpNEMmj-WHv2V9xfk2aRf7yB2-yX973XQ3JM0VUCnM8_rS-GZqhbl/s400/capcom2.gif" alt="" id="BLOGGER_PHOTO_ID_5207482623973296850" border="0" /></a></p> <p><img src="http://hyperphysics.phy-astr.gsu.edu/hbase/electric/imgele/capcom3.gif" /> </p><p><strike><img src="http://hyperphysics.phy-astr.gsu.edu/hbase/electric/imgele/ceq.gif" /></strike>=<span style="font-size:130%;">14.286</span> <img src="http://hyperphysics.phy-astr.gsu.edu/hbase/electric/imgele/mf.gif" /></p>tambarihttp://www.blogger.com/profile/00551341351972304033noreply@blogger.com0tag:blogger.com,1999:blog-1106722070395327999.post-32979141536717410292008-05-25T18:28:00.000-07:002008-06-02T18:31:43.054-07:00Voltage Law<div style="text-align: justify;">he voltage changes around any closed loop must sum to zero. No matter what path you take through an electric circuit, if you return to your starting point you must measure the same voltage, constraining the net change around the loop to be zero. Since voltage is electric potential energy per unit charge, the voltage law can be seen to be a consequence of conservation of energy.<br /><br />The voltage law has great practical utility in the analysis of electric circuits. It is used in conjunction with the current law in many circuit analysis tasks.<br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEibmVxXgWrWf_agACVyTWcpxpRZkXMeeY5D0GlTM7WJrNEcRbDrQA3rhKIsAas0p83Ge7XeqQd7y3Hla-zT4AnORHeXGBrz708q2CvtrqcnYrpNrW1L6Fu6uIWnT_cI32Fr2VDOS2yAcznC/s1600-h/vollaw.gif"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEibmVxXgWrWf_agACVyTWcpxpRZkXMeeY5D0GlTM7WJrNEcRbDrQA3rhKIsAas0p83Ge7XeqQd7y3Hla-zT4AnORHeXGBrz708q2CvtrqcnYrpNrW1L6Fu6uIWnT_cI32Fr2VDOS2yAcznC/s400/vollaw.gif" alt="" id="BLOGGER_PHOTO_ID_5207461386597935458" border="0" /></a>The voltage law is one of the main tools for the analysis of electric circuits, along with Ohm's Law, the current law and the power relationship. Applying the voltage law to the above circuits along with Ohm's law and the rules for combining resistors gives the numbers shown below. The determining of the voltages and currents associated with a particular circuit along with the power allows you to completely describe the electrical state of a direct current circuit.<br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi_RlyVWFMVGSZ_bBg-3Fj9H7ZskHqDAkM2VovIojR1TKjMvcADLMQczKfP_RIbwb0NhBBrBsNYm_SvHtLkBUyF485UbIDDBUP6BTg6G-QZ_79pOSv0H28dBrPhLzaG3ytd68QO5CIBDotC/s1600-h/vollawa.gif"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi_RlyVWFMVGSZ_bBg-3Fj9H7ZskHqDAkM2VovIojR1TKjMvcADLMQczKfP_RIbwb0NhBBrBsNYm_SvHtLkBUyF485UbIDDBUP6BTg6G-QZ_79pOSv0H28dBrPhLzaG3ytd68QO5CIBDotC/s400/vollawa.gif" alt="" id="BLOGGER_PHOTO_ID_5207461493661413026" border="0" /></a><br /></div>tambarihttp://www.blogger.com/profile/00551341351972304033noreply@blogger.com1tag:blogger.com,1999:blog-1106722070395327999.post-19419829373330784982008-05-23T21:43:00.000-07:002008-06-02T21:46:16.007-07:00Voltmeter<div style="text-align: justify;">A voltmeter measures the change in voltage between two points in an electric circuit and therefore must be connected in parallel with the portion of the circuit on which the measurement is made. By contrast, an ammeter must be connected in series. In analogy with a water circuit, a voltmeter is like a meter designed to measure pressure difference. It is necessary for the voltmeter to have a very high resistance so that it does not have an appreciable affect on the current or voltage associated with the measured circuit. Modern solid-state meters have digital readouts, but the principles of operation can be better appreciated by examining the older moving coil meters based on galvanometer sensors.<br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjvlT8hEsky79uy_5rJCWrRiN63pBeRvwYZVSCa62mNpmJ_km-JzKNmgozASxgcjZLrXyVlYywGYGAAMd5ot9Pr-7t_BNP4CA0jQ0-KcYIwvj4jJNtQo22ZfrjfAW72RvHKCJ4dvotkngpt/s1600-h/mmet.gif"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjvlT8hEsky79uy_5rJCWrRiN63pBeRvwYZVSCa62mNpmJ_km-JzKNmgozASxgcjZLrXyVlYywGYGAAMd5ot9Pr-7t_BNP4CA0jQ0-KcYIwvj4jJNtQo22ZfrjfAW72RvHKCJ4dvotkngpt/s400/mmet.gif" alt="" id="BLOGGER_PHOTO_ID_5207511515026316274" border="0" /></a></div>tambarihttp://www.blogger.com/profile/00551341351972304033noreply@blogger.com1tag:blogger.com,1999:blog-1106722070395327999.post-56283005595915129182008-05-23T20:02:00.000-07:002008-06-02T20:05:34.470-07:00Electric ChargeThe unit of electric charge is the Coulomb (abbreviated C). Ordinary matter is made up of atoms which have positively charged nuclei and negatively charged electrons surrounding them. Charge is quantized as a multiple of the electron or proton charge:<br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgxdjVL5z9J6a38Lkh_GglEZ5VMM1CHmJUbz-CKaWiqCO18JE0qgYU0Q48GbsxX-AhxLz8qpwB1xni1lRBqi7L4Z1jwQ-ga4o1v6XRz1ehSoT_VAUNU9471HA_LJfYU6z_81ZQJyQXoJGKD/s1600-h/echg.gif"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgxdjVL5z9J6a38Lkh_GglEZ5VMM1CHmJUbz-CKaWiqCO18JE0qgYU0Q48GbsxX-AhxLz8qpwB1xni1lRBqi7L4Z1jwQ-ga4o1v6XRz1ehSoT_VAUNU9471HA_LJfYU6z_81ZQJyQXoJGKD/s400/echg.gif" alt="" id="BLOGGER_PHOTO_ID_5207485851916690498" border="0" /></a>The influence of charges is characterized in terms of the forces between them (Coulomb's law) and the electric field and voltage produced by them. One Coulomb of charge is the charge which would flow through a 120 watt lightbulb (120 volts AC) in one second. Two charges of one Coulomb each separated by a meter would repel each other with a force of about a million tons!<br /><div style="text-align: justify;"><br />The rate of flow of electric charge is called electric current and is measured in Amperes.<br /><br />In introducing one of the fundamental properties of matter, it is perhaps appropriate to point out that we use simplified sketches and constructs to introduce concepts, and there is inevitably much more to the story. No significance should be attached to the circles representing the proton and electron, in the sense of implying a relative size, or even that they are hard sphere objects, although that's a useful first construct. The most important opening idea, electrically, is that they have a property called "charge" which is the same size, but opposite in polarity for the proton and electron. The proton has 1836 times the mass of the electron, but exactly the same size charge, only positive rather than negative. Even the terms "positive" and "negative" are arbitrary, but well-entrenched historical labels. The essential implication of that is that the proton and electron will strongly attract each other, the historical archtype of the cliche "opposites attract". Two protons or two electrons would strongly repel each other. Once you have established those basic ideas about electricity, "like charges repel and unlike charges attract", then you have the foundation for electricity and can build from there.<br /><br />From the precise electrical neutrality of bulk matter as well as from detailed microscopic experiments, we know that the proton and electron have the same magnitude of charge. All charges observed in nature are multiples of these fundamental charges. Although the standard model of the proton depicts it as being made up of fractionally charged particles called quarks, those fractional charges are not observed in isolation -- always in combinations which produce +/- the electron charge.<br /><br />An isolated single charge can be called an "electric monopole". Equal positive and negative charges placed close to each other constitute an electric dipole. Two oppositely directed dipoles close to each other are called an electric quadrupole. You can continue this process to any number of poles, but dipoles and quadrupoles are mentioned here because they find significant application in physical phenomena.<br /><br />One of the fundamental symmetries of nature is the conservation of electric charge. No known physical process produces a net change in electric charge</div>tambarihttp://www.blogger.com/profile/00551341351972304033noreply@blogger.com0tag:blogger.com,1999:blog-1106722070395327999.post-8503167383689273382008-05-21T21:46:00.000-07:002008-06-02T21:48:18.360-07:00AmmeterAn ammeter is an instrument for measuring the electric current in amperes in a branch of an electric circuit. It must be placed in series with the measured branch, and must have very low resistance to avoid significant alteration of the current it is to measure. By contrast, an voltmeter must be connected in parallel. The analogy with an in-line flowmeter in a water circuit can help visualize why an ammeter must have a low resistance, and why connecting an ammeter in parallel can damage the meter. Modern solid-state meters have digital readouts, but the principles of operation can be better appreciated by examining the older moving coil meters based on galvanometer sensors.<br /><a onblur="try {parent.deselectBloggerImageGracefully();} catch(e) {}" href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhhN0Gh41ziusofmkryI79alFg9Ls1qFhaJh_p7JGihEV6e3REMYgA4IaO3K8qvC6f9Mf4mX8POL6_fa9L0v9mRLjoqAKpBhvWI1im42rg-gSZHV4B6LxL8FKUu0WfoIpJ9CxNHYrVUbh5p/s1600-h/amet.gif"><img style="margin: 0px auto 10px; display: block; text-align: center; cursor: pointer;" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhhN0Gh41ziusofmkryI79alFg9Ls1qFhaJh_p7JGihEV6e3REMYgA4IaO3K8qvC6f9Mf4mX8POL6_fa9L0v9mRLjoqAKpBhvWI1im42rg-gSZHV4B6LxL8FKUu0WfoIpJ9CxNHYrVUbh5p/s400/amet.gif" alt="" id="BLOGGER_PHOTO_ID_5207512311468576082" border="0" /></a>tambarihttp://www.blogger.com/profile/00551341351972304033noreply@blogger.com0