-
Touch phase wire
Can we Touch phase wire in air when we r not touch ground what happens
amolgaonkar
- Dec 9th, 2011
When you touch the phase wire in air the current will enter your body but it will have no way to escape or complete the circuit thats why you will not feel the shock...the best example is you might ha...
Tarun Aggarwal Ymca
- Jul 22nd, 2011
only high potential cannot cause flow of current. So, when a Human being touch such a wire, its whole body is at a high potential, but due to the absence of a lower potential, the current cannot flow....
-
Alternator Regulation
Why most of the alternator is connected in star and have high regulation around 30% as compared to transformer?
sinuhe
- Dec 7th, 2011
There will be a large amount of third harmonics in current flowing "inside" the delta connected generator.
Raman Jain
- Dec 3rd, 2009
The cost of insulation is the deciding factor . If one is using delta connection , the insulation required will be for Ph-Ph voltage but in the case of Star connection the voltgae will be 1/1.732 times. So cost will be less.
-
Electric motor start-up
Why there is a fivefold increase in a current at electric motor start-up?
eng: ahmed gharieb
- Dec 5th, 2011
Every thing in the first being hard but with time it get better. The IM is one of this thing, as in the start n=0 so that the equivalent cct of IM
exactly as before
Thanksbittu123
- Nov 8th, 2011
If You may be talking about DC motor, here is the explanation........ current through rotor is given by i=(V-E)/R. But during starting no emf is induced, E=0, So, i= (V-0)/R must be greater than if ...
-
-
Neutral Circuit and Core Balance Circuit Protection
What is the difference between neutral circuit and core balance circuit protection?
Raman Jain
- Nov 25th, 2011
In neutral circuit protection , the CT is placed in neutral conductor and it is true earth fault protection.
on the other hand , in core balance protection the CT is placed in 3-phase cable and measured the unbalanced current in the cable. So it is protection against the unbalance between phases. -
CT Earthing
Why ct earthing should be connected at one end only? if ,we connect more than one end means what will happen?
-
Power Supply Phase
Why do we use a single phase and a three phase power? Why dont we use two phase or four phase upward?
bittu123
- Nov 10th, 2011
Continuing my answer............... I wrote above "Differentiating single and double phase is really a big task. As single phase stand alone don't work, it always need neutral(returning path), U may ...
bittu123
- Nov 9th, 2011
As we increase the phase, output rating of machine also increases(like output rating of 3ph is 1.5 times more than 1 ph),pulsation in output decreases, this really encourage to have greater phase BU...
-
DC Generator Brush
Why the brush is fitted in M.N.A axis? What is its effect on speed?
bittu123
- Nov 9th, 2011
Since reversal of current take places at MNA not at GNA, So, commutation can be improved by putting brush at MNA. Otherwise it leads sparking and damaging brushes and commutator. If load connected ac...
Nishant Choudhary
- Jun 3rd, 2011
It does not effect the speed it is done to reduce sparking at the commutator contacts
-
APFC Panel Circuit Fuse Units
Why We should use only Fuse units in APFC Panel circuit instead of ACB/MCCB/MCB?
bittu123
- Nov 8th, 2011
Automatic power factor correction panels will control the load power factor by sensing various available parameters like Current, Power Factor, and KVAR.... Since sensing units are already there whi...
-
Contactors in circuits
Why we use contactors in ckts....how many types of contactors are there.. how we select the contactor for in ckt for its operation
bittu123
- Nov 8th, 2011
Contactor is basically a large relay kind of thing which is used to switch large amount of power. It has multiple contacts and all contacts can be switched together. all multiple contacts are controll...
-
Electrical Wiring and Circuit Questions
1)How much current can a 3-1/2 core 100 mm wire carry?
2)What is the latest generation of circuit breakers called?
3)What are the special cables required for explosion proof wiring?
4)What are the different types of soft starters for large motors?
5)What is the similarity and what is the difference between relays and PLC?bittu123
- Nov 8th, 2011
I am answering few of them................. 1)How much current can a 3-1/2 core 100 mm wire carry? - It depends on "what conductor(aluminium, copper or else) you are using" and "whether it is insula...
-
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...
-
Capacitor Connection
Why the capacitors are connected in delta? What advantage it having than star connection?
bittu123
- Nov 8th, 2011
Prime reason : Delta connection will give 3 times more reactive power(kVARs) than star connection.
there are few more reason....
1. less triplen harmonic
2. less heat loss, since current is I/1.732 where I will be the current star connection pr phase
-
PNPN Thyristor
Why PNPN is used as thyristor NPNP is not used?
bittu123
- Nov 8th, 2011
Funny, what differences PNPN & NPNP makes? If you have PNPN thyristor, its kept on table, U are seeing PNPN, right? Now, keep its back in front, whats this now? NPNP......isn't that? its not transist...
-
Phase Advancer
Why Phase Advancer is not used in below 200kva machine?
bittu123
- Nov 8th, 2011
During starting or low load condition IM works on very lagging current which results in taking high current. This sudden high current may creats transient in power system, which is undesirable. Phase ...
-
American Distribution System
What is the difference between American and Indian distribution system? Which one is better and why?
bittu123
- Nov 8th, 2011
AMERICAN : frequency 60Hz House hold voltage: 120v and 240v Split phase 3 wire service INDIA: frequency 50 Hz House hold voltage : 230v and 4...
-
Power Measurement
Why current coil and pressure coil of wattmeter is connected in different phases for reactive power meaurement?
bittu123
- Nov 8th, 2011
You have to draw a phasor diagram. then U will get it easily. Draw Vr, Vy, Vb with 120 degree displacement. Now draw Ir leading(lagging) Vr by some angle, Say 0. and Iy displaced 120 degree to Ir, sa...
-
Earth Fault
What is the technical difference between earth fault and earth lekage relays ?
bittu123
- Nov 8th, 2011
Earth fault : If live wire gets touched to the earth, heavy current start flowing through this wrong path, causing short circuit and considered to be a kind of fault. Earth leakage relay: Instrument ...
-
Is possible to increase the voltage without using transformer? why?
bittu123
- Nov 7th, 2011
I went through all answer, seems all are correct.... But lemme be more precise.. Except transformer..... 1. CHOPER: It is said to be DC equivalent of AC transformer, so can be used to increase and d...
santosh
- Nov 7th, 2011
We can step up and down dc voltage using chopper circuit
-
Lightning Arrester
what is lightning Arrester? what the use of this in substations?
Electrical Engineering Interview Questions
Ans