Question { 22398 }

1. What is the difference between ac induction motor
and ac synchronous motor?

Answer

1. Synchronous motor runs at synchronous speed but the
induction moror can't, if it does so then it will stop
because the rotor conductors will not cut the magnetic
field & induction principle will fails.
2. Synchrounous motor can improve power factor but
induction motor can't.
3. Synchrounous motor is costly as compared to induction
motor.
4. Synchrounous motor has two types excitations but in
induction motor has only one type excitation.
5. Synchronous motor can't run at other speed without
synchronous speed, if it does so then it will fall out of
synchronism & will stop.
6. There is requirement of any auxilary help for starting
the synchronous motor like pony motor,with the help of
manual rotation, by inserting the copper cage into its own
rotor(means starting as squirrel cage motor), but there is
no requirement of any help to start the induction motor.

Question { 9270 }

Where there is voltage,there must be current.Is this right
or wrong??

Answer

No, as per asked question it is not true that if there is
voltage then there will be current, but if there is current
then there will surely be voltage.

* Voltage is only a pressure for the flow of charge but if
there is a pressure then it is not necessary that current
will surely flow because current cannot flow without of any
medium but voltage/emf can exist in open circuit.

-))>I think Beyond this there is no need for explaination.
amrit.tics@yahoo.co.in

Question { 6967 }

what is the working principle of dc motor & its
application ?

Answer

DC Motor Principle: Whenever a current carrying conductor
is placed in any magnetic field it will experience a force.
Uses:- DC motor is used in traction work, toys,high torque,
crane work,elevators, etc.

Question { 4250 }

how DC is differ from AC ? what are the difference between
them ?exept (P-N)&(+__-)

Answer

AC is differ from DC as per given below:
1. In AC transformer can be used but in DC we can't use
transformer.
2. In AC can't be stored but DC can be.
3. In AC there is skin effect but in DC there is no skin
effect.
4. There is revolving field in 3-phase AC machines but
there is no revolving field in DC machines.
5. AC switch gears are cheap,robust,easily maintence but DC
switch gears are not.

Question { Equate, 15942 }

HT motors are generally connected in star, what will be the
effect if we connect HT motor in Delta?

Answer

I think the H.T. motor is connected in star, to take its
grounding point.

Question { 12062 }

why field rhoestat is kept in minimum position while armature
rheostat at maximun position?

Answer

The given answer is correct but here it depends upon the
type of motor that either the motor is series wound or
shunt wound. Because in case of series wound motor the
armature as well as field winding are connected in
series..........But the same is done due to attain high
starting torque.

Question { 6485 }

what is the basic principle of the alternator ????

Answer

The principle of Alternator is Electromagnetic Induction,
i.e. whenever a conductor cuts the magnetic flux an emf
will induce in the same conductor.
Same process is done in alternators, as we rotate the rotor
of the alternator, due to that its conductors cut the
magnetic flux & emf is induced in the rotating conductors,
which is collected with the help of slip-rings......!

Question { 5367 }

why we cannot cool the room by opening the refrigerator ?

Answer

Because in case of opened refrigerator, the refrigerator
takes the room heat but also emits the motor heat(during
working) so due to that Total Heat In Room = Room Heat +
Refrigerator Motor Heat.
* So over all the refrigerator cannot cool the room but it
will slightly increases the room temp.

Question { MAHINDRA, 22671 }

what is the meaning of electrical maintenance?

Answer

Electrical maintenance means the care & checklist of electrical
equipments/instruments to avoid any brekdown or fault.To tighten
the all electrical connections, to upgrade the power rating of
safety-switches is also a part of Electrical Maintenance.