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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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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 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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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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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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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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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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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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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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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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PF Card Function
A powerplant has 8 gensets operating in grid parallel mode. In one genset sometimes there is pf variation and kvar variation. The plant operates in pf mode. When this variation is observed the load is stable, voltage is also stable, freq and genset speed is also stable. How will you check the functioning of pf card. What shall be the ideal output vdc of the pfc, from there it is input to AVR?
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Earthing Resistance
What will be the body impedance of human body>What will be the maximum allowable earthing resistance value?
bkashwin
- Jul 1st, 2010
The resistance of human body is 1000 ohms and allowable resistance is 1000 ohm for some time.
csbalu
- Aug 29th, 2009
Human body impedence depends on the nature of the body and it varies appreciably between different sizes. The fatter the lower resistance.The acceptable earth resistance will be less than 1 Ohm - the lesser the better.
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Power Factor
A powerplant has 8 gensets operating in grid parallel mode. In one genset sometimes there is pf variation and kvar variation. The plant operates in pf mode. When this variation is onbserved the load is stable, voltage is also stable, freq and genset speed is also stable. How will you check the functioning of pf card. What shall be the ideal output vdc of the pfc, from there it is input to avr.
mani777
- Jun 23rd, 2010
1. pf...........cos #=watt/voltage*current2. pf is cos thita between v & i3. pf is apperent power/realor reactive power.
saginala13
- Jun 19th, 2010
here the variation in the power is is the pf factor of load, in generating station all alternators are connected to a busbar, and load is connected to bus bar so the load will be shared by all generators
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How do you measure the leakage current in a house wiring?
bittu123
- Nov 9th, 2011
Two method suggested above is right.
Beside those,
Measure current through live wire and neutral wire at main switch board of ur house and find the differences.mani777
- Jun 22nd, 2010
There are two ways for it. First one is to keep all lights and other domestic electric appliances OFF for an hour and record the energy consumption in the energy meter. Calculate current from it. Seco...
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AC line Power Loss
High voltage is traded off for lower current in an AC line transmission. High current would require thicker cables, hence losses. How much can the voltage be increased to have a lower power loss? What is the ratio b/w current and voltage (p = I^2 * R).
Jayrod
- Jun 21st, 2010
"High current would require thicker cables, hence losses." - I disagree. The larger the cross-sectional area of a cable, the lesser the resistance (remember the formula for resistivity). Thi...
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Harmonics Deduction
How can we control or deduct harmonics?
veerateja
- Jun 18th, 2010
By improving the power factor by using capacitor or by synchronous condenser the harmonics can be reduced.If three phase is used the harmonics can heat the neutral wire ,so it is better to keep the diameter of neutral wire more than the other phases.
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Transformer Core Loss
What is core loss in a transformer?
veerateja
- Jun 16th, 2010
Eddycurrent and hysteresis losses are two core losses in transformers. Eddy currents are minimised by laminating the core where as hysteresis losses are minimised by using pure silicon steel. The two losses are similar in all rotating electrical machinery.
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Main Switch
What the name given for to connect the main switch supply to the various appliances?
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Vibro Motor Direction of Rotation
Two electrically operated Vibro Motors are fixed in parallel direction in vibrating feeder. What is the direction of both Vibro Motors?
Electrical Engineering Interview Questions
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