A 4 point starter is used to start and control the speed of a (GATE-EE-2011)
(A) dc shunt motor with armature resistance control
(B) dc shunt motor with field weakening control
(C) dc series motor
(D) dc compound motor
Answer: option (A)
The armature current of DC shunt motor
Ia = (V- Eb) /Ra.
at the time of starting, Eb = 0. If the full supply voltage is applied to the motor, it will draw a large current due to low armature resistance.
A variable resistance should be connected in series with the armature resistance to limit the starting current.
(A) dc shunt motor with armature resistance control
(B) dc shunt motor with field weakening control
(C) dc series motor
(D) dc compound motor
Answer: option (A)
The armature current of DC shunt motor
Ia = (V- Eb) /Ra.
at the time of starting, Eb = 0. If the full supply voltage is applied to the motor, it will draw a large current due to low armature resistance.
A variable resistance should be connected in series with the armature resistance to limit the starting current.
why 4 pointer is not used to control the shunt motor with field weakening control
ReplyDeleteI think so
ReplyDelete3 point starter has the drawback of field weakning to achieve the speed above the rated speed
ReplyDeleteI think 4 point starter used for field weking cantrol
ReplyDeleteFour point starter used for above rated Speed. So, answer is B
ReplyDeleteBecause in 4 point starter No Volt Coil directly connected to the supply voltage
ReplyDeleteDC shunt motor with armature resistance control
ReplyDelete