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Corona Effect
What is corona effect ? How this is avoided in transmission?
silverscythe
- Jul 2nd, 2010
Corona Effect is the high voltage electric discharge phenomenon that can be observed between two transmission lines or for that matter any two lines carrying electricity. This occurs generally when th...
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Insulation Value
What is the thumb rule for insulation value in bus bars, phase to phase and phase to earth for 11 & 33 kV system?
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Insulation Resistance Testing
When we apply the DC voltage thro' the digital Megger to test the IR value for cable/motor winding etc., we can see the digital display of the test equipment showing more than the applied voltage (for eg. if we select 500V dc, we can see 526V dc in the display) Why?
sinhasunilk
- Jul 3rd, 2010
When we measure IR value, we measure resistance of insulation of the circuit either w.r.t earth or w.r.t. to other phase.The digital display is resistance between the ckt and earth, not the voltage. I...
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Alternator
Why alternator is operated at lagging power factor?
How alternator responses with changing the load?sinhasunilk
- Jul 3rd, 2010
The Alternator has very little margin to run in the leading P.F. so far electrical stability of alternator is concered. If we operate generator at higher leading P.F. machine will become uns...
rajakumar1985
- Sep 9th, 2009
Since the Synchronous generator having the property of supplying the reactive power along with the real power, this can be operated in lagging power factor only. Suppose if it want to work with leadin...
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Inductive Loads
Why does inductive loads consume KVARs?
sinhasunilk
- Jul 3rd, 2010
Electrical load is of three types: Inductive load, Resistive load and Capacitive load.The power drawn in a circuit will depend on type of load, the power is supplied. The circuit which has i...
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3 Phase Motor
How can we test a 3 phase motor on single phase supply?How can we run a 3 Phase Motor on Single Phase supply for testing?How can we verify of a 3 phase motors' 6 wire & name them a1/a2/a3..b1/b2/b3 and c1/c2/c3 for connecting star delta starter?
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Earthing Standards
What is the standard for Cable sizing & Voltage Drop?What is the standard for earthing?
maxandrean
- Jul 5th, 2010
Standart Earthing Cable in practice is :1. For the cable size is 16 mm2 , the size is equal to the line cable.2. For cable size above 16 mm2, the size is half size of the line cable, but not less than...
salman_moazzam
- Feb 2nd, 2010
Depth to which you must dig. How much should be the amount of salt and charcole to be put. Especially in earthing we must go to the depth untill you get wet mud.
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Power Factor Panel
What will happen if 400 KVar Capacitor banks are on in manual mode and there is no load on mains?
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Vector Group
What is vector group of transformer? Why is it required?
raviiisc
- Jul 11th, 2010
Vector group is a big topic which comes in case of Three Phase transformer connections.There are some connections like Dd0, Dd12, Yy0, Yy12, Dy, Yd.......and so on.Here 180 degrees group,0 degrees gro...
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Power Distribution
How much load is required to convert 100 KW Single Phase load to 3 Phase Load?
sinhasunilk
- Jul 12th, 2010
Load is represented in KW. Whether it is single phase or thre phase, same load is to be supplied. You have asked the conversion of 100KW single load to 3 phase load. In three phase equvalent load will...
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Convert Single Phase to 3 Phase
How to convert a single phase supply to a 3 phase balanced supply?
raviiisc
- Jul 14th, 2010
The are two methods.1. First convert 1-ph AC into DC by using converter, then that DC is converted to AC by using the power electronic circuit named as three phase inverter using any modulation t...
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Voltage Levels
Why all voltage level are multiples of 11, like 220V, 440V, 1100V instead of 200V, 400V, 1000V?
pradipsabar2009
- Jul 30th, 2010
The value of form factor is 1.1 which is calculated for the sine wave. At this value of form factor, leakage flux is minimum and efficiency is maximum for any electrical machines. These machines are operated at sine waves.
dhrumil041189
- Jun 11th, 2010
Because number of disc of insulators are rated in order of 11 kV so all these are transmitted in the multiple of 11.
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Power Between Source and Load
When eletricity is not used what happens to power between source and load?
pradipsabar2009
- Jul 30th, 2010
The power generated by source quickly responds to the load. If the load is suddenly disconnected, there will be only line load present so source cannot quickly change itself as a result heavy transien...
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Fault Detection in Underground Cables
If there are three underground cables if a fault takes place in one of them, How will you detect it?
pradipsabar2009
- Jul 28th, 2010
Measure the resistance of each cable between farther ends, if there is a considerable variation in any one of the cable, that is the faulty one. This method is also used in industries called as "Insulation Resistance Test".
dhands
- Jun 6th, 2010
1. Check phase to pase insulation resistance value and phase to earth insulation resistance value.
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Bulb Power
The bulb has a rating of 500W for 220V, if the voltage is 110V, What is the power of the Bulb?
mohit parashar
- Jul 28th, 2010
Given:p=500WV=220VP=VII=2.27Athan by ohm's lawV=IRso R=96.91Ohm which is constant.if V=110Vthan I become 1.135AsoP=VIP=125W.
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Quality Factor in Resonance
What is the importance of quality factor in resonance?
sujit.185
- Aug 5th, 2010
QUALITY FACTOR actually signifies the voltage gain or voltage amplification factor of a given ckt.
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Electrical Machine Harmonics
What is harmonics and how they are produce in electrical machine?
ravs42
- Aug 6th, 2010
Harmonics are the integral multiples of the fundamental values of current/voltage quantities. Generally it is caused due to non linearity caused by the load which adversely affects the supply side. Main impacts occurs in capacitors, telecommunication lines, power transformers, etc.
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Spark Plug
When the power supply cable got sparked, it gets burnt or caches fire then explain why the spark plug in our automobiles never get burnt or catch fire even it spark's?
ravs42
- Aug 6th, 2010
Generally in automobiles we have an alternator that produces ample AC supply that is converted to 12V DC supply via the help of rectifiers and regulated IC usage. The 12V is then feed to the batterri...
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Transformers and Varying DC Current
Will DC current that varies, for example a DC square wave, but that only sinks to neutral (0V) and not enough to cause current to flow in the opposite direction, pass through a transformer? If so, how will you be able to calculate reactance for this?
ravs42
- Aug 8th, 2010
A DC square wave will have a very high value of dv/dt as compared to the pure sine wave. When it is striked to transformer, a high value of dv/dt would not be responded by it, as a result, the waves ...
Abhijit_atrangi
- Feb 22nd, 2010
No, only change in flux will induce the emf in a ckt. and that only feasible with AC that goes in opposite direction also. But in case of DC that produce flux with no change that never cause any emf in circuit. In case of DC square wave you change the magnitude of a wave from zero to max.
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