30.

31.

32.

33.

34.

A 100 hp, 250 V, 350 A de shunt motor with an armature resistance of 0.05 Q, is started bya
starter having 4 stages of resistances. Starter is designed to limit maximum starting current
to twice its rated value and its starting minimum current to rated value. The total resistance
of starter is :

(A) 1.60 Q (8) 1.55 ©
(0 1.502 (D) 1.45 ©

Identify correct and incorrect statements related to synchronous machine :

]. The synchronizing torque or stiffness of coupling, in a synchronous machine, increases
with increase in load angle ‘6d’

11. The Steady state stability limit or maximum power transfer condition, in cylindrical
rotor and salient pole synchronous machine, occurs at load angle 6 = 90°
(^) Tand II both are incorrect
(8) Iand II both are correct
(C) Tis correct, but II is incorrect

(1) Tis incorrect, but II is correct

Identify the incorrect statement related to synchronous machine :
(A) A largely Over Excited Synchronous Generator delivers P and Q, with lagging
power factor
(B) A largely Over Excited Synchronous Motor consumes P, but delivers Q, with
leading power factor
(C) Alargely Under Excited Synchronous Generator delivers P, but consumes Q, with
leading power factor

(D) A largely Under Excited Synchronous Motor delivers P and consumes Q, with
lagging power factor

The commutator pitch for 4 pole, 50 commutator segment, retrogressive, Duplex-wave wound
DC machine is :

(A) 12 (B) 14

(C) 24 (D) 26

If a squirrel cage induction motor, when started with 50% tapping in case of
auto-transformer starter and stator reactor starter, then the ratio of starting currents
respectively is :

(A) 0.25 (B) 0.50

© 1 (D) 2

080/2023 8 A