Inspite of heavy initial investments, dc motors are used due to
The control of dc machines is very much simplified when compared to other machines. So this makes it very useful when compared.
Separately excited dc generators are used in
Separately excited dc generators are used in Ward leonard system of speed control.
Maximum torque in dc series motor is limited by
Commutation is the process which reduces the induced emf and so the torque.
Hoists, cranes and battery powered vehicles use _________ motors in the locomotive.
Hoists, cranes require large starting torque which can be provided by dc series motor.
There is an application which required pulsating loads, punch presses. The most preferred machines would be
It is compound machine whose flux can varied higher as well as lower in order to have variable torques.
The manufacturer has mentioned a medium starting torque and 15% speed regulation. The most appropriate motor for his requirement is
The dc shunt motor provides a medium values of the torque.
Centrifugal pumps, fans-blowers use
Centrifugal pumps, fans-blowers use shunt as well as induction motor.
Most commercial compound dc generator are normally supplied by manufacturers as over compound machines because
It is usually over compounded so that degree of compounding can be adjusted by diverters across series field.
Which of the following are applied with differential compound motor?
Practically it is never used as the speed can rise very high.
Most commercial compound dc generator are normally supplied by manufacturers as ______ compounded machines.
Most commercial compound dc generator are normally supplied by manufacturers as over compounded.
Long back ago, magnetic casette were in use, having permanent magnet dc motors which had
PMDC motors have field fixed on the stator and rotor has coils.
. If a dc shunt motor is stopped by forcing starter handle back to OFF position, then
The sparking will occur at the last stud not all the studs of the starter.
Interpoles are used to start the dc motor above the base speed.
Interpoles do not reduce the flux across the windings, hence the speed does not rise above base speed.
A 200 V dc motor has external resistances of Ra and Rf in armature and field circuits respectively. The starting current is reduced when
When Ra is maximum and Rf minimum then the current to the armature is reduced. And hence the sparkings are reduced while starting.
A d.c. generator has been provided tappings on the armature winding at intervals of 120 degrees from the side of commutator. The connection will be
Dc generator if has displaced by 120 degrees physically then it will be act as ac machine.