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Harmonics
How harmonics are produced in m/c what is its physical significance?
naveen.rangu
- Nov 28th, 2008
Harmonics are produced in machines due to non uniform distribution of flux produced by field winding in the air gap. This leads to trapezoidal wave form instead of sinusoidal wave contains multiple of? fundamental frequncy called harmonics after analysed by fourier series.
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Busduct & Rising Main
Explain what are busduct and rising main? Where it is used?
sindhejs
- Feb 16th, 2009
Bus ducts are the mechanical protection to the bus bars, may be rectangular or square hollow boxs.
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Voltage Drop
How to calculate the voltage drop in cable?
ssooria
- Dec 4th, 2008
1) what is the load= KW2)from that calculate the actual current, I = KW &nb...
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PID control
Give brief detail on PID Control.
SURAJTHEGREAT
- Mar 3rd, 2009
A controller is a device employed to obtain a stable output. There are many controllers of that PID controller is the most widely used. A proportionalintegralderivative controller (PID...
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Neutral Earthing
What is neutral earthing and equipment earthing?What are the advantages of grounding a neutral of a transformer and gernator?
SURAJTHEGREAT
- Mar 3rd, 2009
Nuetral point is useful. Bcoz the extra current flows to the ground. Ground is always at a higher polarity than the device. For example consider your instant heater. It always is a 3 pin plug point....
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Wattmeter
Wattmeter has two coils in it-the current coil & pressure coil, why is the pressure coil so named? How is the power being measured by the Wattmeter?
mallick.subratkumar
- Mar 21st, 2009
Current coil means it measure current of circuit & pressure coil means it measure voltage, when current coil is connected series, pressure coil connected parallel in one circuit ,as P=V*I*cos?,
So we have V, I, & ?=[1/tan(V/I)],
Now the power is being measured. -
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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Electrostatic Power
Is it possible to generate electrostatic power? If yes, how?
bittu123
- Nov 8th, 2011
Yes electrostatic power generation is possible as VAN DE GRAAFF generator is best example of it. But this is not economical and usable for general purpose, So, Electrostatic power generation is not pr...
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Transformer Shutdown and Trip
What is the differance between shutdown and trip?
sindhejs
- Feb 18th, 2009
Purposely making the transformer stop(down) is the shutdown,for the purpose of maitainance etc.Unevenly stop the transformer due to any faults; is the Trip.
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Magnets in Speaker
Why magnets are used in audio speaker?
SURAJTHEGREAT
- Mar 3rd, 2009
We know audio signals are going be as signals (ac signals are those whose amplitudes are constantly changing). The speaker system employs 2 magnets. 1-Electromagnet, 2-Permanant Magnet. When 2 mag...
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Units Calculation
How many units will a 40W tube consume in 1hr 15 minutes 20 seconds?
SURAJTHEGREAT
- Mar 2nd, 2009
1 unit=1000 watts.Therefore 40 watts=0.04 units.(40/1000)If the light consumes 0.04 units for 1 hour.then for 15 min it is (0.04/4)=0.01 unitsI calculated this way(1 hr=4*15 min...Then for 15 min(divi...
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Vector Quantity
Is current a Vector quantity? If yes, then two wires on 90 degree angle must have resulting current equal to zero.
SURAJTHEGREAT
- Mar 3rd, 2009
According to me, current is neither scalar nor vector completely. It does not obey, vector law of addition. We know kirchoff's law, Current leaving = current entering. So if load is connected at the...
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Tripper Drops
Consider you have a tripper at your house. The instant you switch on your motor, the tripper drops. What could be the problem?
mallick.subratkumar
- Mar 20th, 2009
The tripper drops because the motor is an pure inductive load & when we switch ON it, as the properties of inductive load define it oppose sudden change in current so the tripper drops when motor switch is ON.
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Lightening Arrestor
Location of lighting arrestor should be near transformer or not? Why?
mallick.subratkumar
- Mar 30th, 2009
Yes it must be near to the transformer,because when there is a lightening occurs the total power must go through Lightening Arrestor to ground with out damaging the transformer.
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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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Circuit Breaker
Which Circuit Breaker is better either Air CB or Vacuum CB? Why?
rajakumar1985
- Sep 7th, 2009
The vacuum C.B is better than A.B C.B for medium voltage because of its better operation and longer life. But in high voltages we cant use the vacuum C.B.
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Alternator Operation
If we put field winding on stator and armature winding on rotor then how will it operate? Will it rotate at synchronous speed or not? (Assuming that the alternator is feasible)
nikhilsharma2009
- Sep 15th, 2009
Yes, It would surely operate and run at synchronous speed. But it would be uneconomical because we should have 3 slip rings of very high current handling capacity and because of this efficiency will decrease and we will require to have high level of insulation and cooling also.
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Induction Motor
Why star point of star connected motor is not grounded?
rajakumar1985
- Sep 10th, 2009
Normally the 3 phase induction motors are not star connected. In the star connected machine, the phase voltage will be 1/ 3 times. So that the torque of the machine will be reduced. Because of this reason normally all the induction motors are having delta connected field windings.
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Motor Frequency
Motor manipulator detail is 230v 50hz frequency. If you increase frequency what will happen?Is there any need for coil protection?
vijay5586
- Oct 19th, 2009
Speed N=120f/p so if we increase the frequency the seed will also increase as per our electrical stands in India we are maintaining 50Hz as the constant frequency it is better maintaining the freq...
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Phase Shifting
Why do we use phase shifting at Current Transformer?
raul10
- Apr 8th, 2009
We use phase shifting in current transformer to transfer the magnetic flux density around the core
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