Answer / madhusudhan

inorder to produce constant magneticfield we required to
apply D.C rather than A.C. which gives variable magnetic
field

Answer / shantanu mishra

The DC current also called field current or excitation
current is given to produce magnetic field in which rotor of
the generator rotates and produces EMF. the EMF can be
varied by regulating field current.

Answer / mahesh

we need a rotational magnetic field of sine wave for the
emf to be induced . if dc is given, the field that is
produced in the air gap is almost a sine wave with constant
magnitude. for ac excitation the air gap flux is not a sine
wave .

Answer / u.vijay bhaskar reddy

for producing constant flux on the rotor

Answer / nagarjunacharya

to produce emf in the stator either we should apply
alternating flux or dynamic(rotating) conductor.as already
we are rotating rotar by prime mover ,wewe have to apply.

Answer / venkatrao chowdary

the dc current produce constant magnetic field.when rotor
conductors are rotated this conductors cuts the magnetic
lines of flux than emf is induced.this emf is called
dynamically induced emf.when ac is given to the alternater
it induces statically induced emf.the operation of
alternater we need dynamically induced emf.so ac is not
given to the alternater.

Answer / u.v.subhashreddy

alternator is an speeed machine. the dc current gives
exication current is given to produce a magnetic field so
giving d.c supply to field of an alternator.

Answer / y.srinath

dynamically induced e.m.f requires fixed polarity& magnetic flux .if we given a.c to field the polarity of a particular pole is not fixed .if one pole behaves as north pole for +ve half cycle & same behaves as north pole for negative half cycle to.that's why we are using d.c supply for alternator.

Answer / b madhu sudhan reddy

alternator is a constant speed machine.i.e it always runs
at synchronus speed.so,for producing constant speed we
require constant excitation.so,for the constant excitation
we require constant supplly.i.e d.c supply

Answer / pravallika

for magnetising poles in rotor

why we use 3 phase in our country?..why no 4,5 or 2??

2 Answers   Siemens,

Actually why the transformers are rated in KVA.?

4 Answers   BSL, Engineering,

What is an Air COmpressor

0 Answers   DLF,

is it necessary for 200 kva transformer to have marshaling box and cu plate earthing for neutral

1 Answers   Blue Star,

10Hp, 3-phase, 415v, 50Hz induction motor. The above motor is to run on Star-Delta connection, so how do i make following hardware selection 1) MCB, 2) Contactor, 3) Wire Gage (Depending on P-P current or Line Current), 4) OLR, Please tell in detail how to do the above, so as to get the ans. of it even if the Hp rating changes.

1 Answers   Engro,

When can we take Neutral as common neutral link?

0 Answers  

Pls mail me utility & Dg related question with answer

0 Answers  

two transformer connected in parallel.tap change are different.if i want to on the buscoupler what happen?

1 Answers   Essar,

Why temperature rise is conducted in bus bars and isolators?

0 Answers  

what is the advantage and disadvantage of billing in kwh and kvah by electricity board .

6 Answers   Nespak, NTPC,

Why is the electric shock from the DC supply is more dangerous than the shock from AC supply.

8 Answers   IBM,

Is current shock due to voltage or current? pls answer

2 Answers   ABB,