Answer / sachin_pawaskar2001

loss of excitation

Answer / nimish

there are so many reasons there may not be a residual
magnetism in d.c. generator then if critical resistance is
more than field resistance

Answer / j.kesavan

some times diodes failur in exciters,thats why voltage not
built in gen set

Answer / swayanjit

if voltage build up is not possible then there may be open
circuit in the field or armature, may be due to dirty
commutator, may be the speed less than the critical spped,
may be the field resistance greater than the critical
resistance.

Answer / shakir

there are so many reasons:
1.the exciter might have problem
2.the ac produced in exciter is converted into dc before
supplying it to the rotor.the diodes used for this purpose
might have problem.
3.when u start the generator there should be a residual
magnetism to induse the voltage.if u will not use the
generator for long time, it will loose that residual
magnetism.for that purpose u have to give flash over
voltage.
4. the exciter winding might be grounded.
5. the input (D.C.from voltage regulator)voltage to the
exciter is not enough to create flux in the exciter.
6.faulty stator winding

Answer / har

avr damaged

Answer / sirisha

it is because the polarities of the field windings are
reversed.

What is a transductor ?

2 Answers  

1.WHAT IS A SMART CAPABLE DB ( DISTRIBUTION BOX) ? 2. HOW TO DECIDE THE TYPE OF DB TO BE USED ( RECESSED/ PLUG TYPE/ SMART ETC ETC? 3. WHAT IS MILLENEUM BUS BAR USED IN DB? 4.DIFFERENTIATE MCCB AND MCB.

0 Answers  

why should we place 9KV lightning arrestors in 11KV substation ?

9 Answers   DOL, ISRO, Matrix,

We have a 33/11kv switchyard having 12.5 MVA power transformer. We export & import power through this transformer. When we export power, the PF will be depend on GRID PF & when we import power the PF will be depend on our load PF. but the problem is that,when neither we export nor import but our 33KV vCB is in close position,our meter read the power factor 0.14 to 0.25 at that moment. So how can be we improve the power factor at that moment.

3 Answers  

why fractional pitch winding generally used in alternators?

0 Answers   TATA,

what will happen when ac is applied resistor,inductor,capcitor?

1 Answers  

What are the tests to be taken on a transformer and generator?

12 Answers   Honeywell,

Fault current shall be part of tech specs of power cable or not?.

1 Answers   DAE,

what is voltage

7 Answers   TCS,

Why we are use dol starter up to 10 hp

0 Answers  

Can I use cable armour as a earth conductor? if not how many GI/CU wires I need to run along with cable?

1 Answers  

Can you tell me more about pu systems (per unit systems )calculation in large power systems? how to get the base for voltage and power in generator, transformator and transmission lines?

0 Answers