In a stepper motor the detente torque means maximum of the static torque with the phase winding excited. minimum of the static torque with the phase winding unexcited. maximum of the static torque with the phase winding unexcited. minimum of the static torque with the phase winding excited. TRUE ANSWER : ? YOUR ANSWER : ?
A frog leg winding is used in a DC machine to eliminate reactance voltage produced due to communication. the use drum winding. the use equalizer in lap winding. the use of compensating winding. TRUE ANSWER : ? YOUR ANSWER : ?
Under which of the following conditions hunting of synchronous motor is likely to occur ? Over-excitation. Periodic variation of load. Over-loading for long period. Small and constant load. TRUE ANSWER : ? YOUR ANSWER : ?
What is the shunt resistance component equivalent circuit obtained by no load test of an induction motor representative of ? windage and friction loss Copper loss core loss only both 1 and 2 TRUE ANSWER : ? YOUR ANSWER : ?
Two transformers operating in parallel will share the load depending on their efficiency leakage reactance ratings per unit impedance TRUE ANSWER : ? YOUR ANSWER : ?
Induction motors normally use cast aluminium rotor because aluminium is cheaper in cost. of low resistivity. lighter in weight. easy to cast owing to its low melting point and is easily available. TRUE ANSWER : ? YOUR ANSWER : ?
A triangular mmf wave is produced in the air gap of an electric machine. Such wave is produced by rotor of an synchronous machine. rotor of a dc machine. stator of a induction machine. stator of a dc machine. TRUE ANSWER : ? YOUR ANSWER : ?
In a synchronous motor when the rotor speed exceeds the synchronous speed during hunting negative sequence currents are generated. the damper bars develop induction generator torque. the damper bars develop induction motor torque. the damper bars develop synchronous motor torque. TRUE ANSWER : ? YOUR ANSWER : ?
A Shunt generator running at 1000 rpm has generated emf of 100 V. If the speed increases to 1200 rpm, the generated emf will be nearly 140 V 240 V 175 V 120 V TRUE ANSWER : ? YOUR ANSWER : ?
Stability of a synchronous motor ---------- with the increase in excitation. increases remains unaffected decreases any of the above TRUE ANSWER : ? YOUR ANSWER : ?