A 220 V DC machine has an armature resistance 1 Ω. If the full load current is 20 A, the difference of induced voltage between generator and motor is 20 V. 40 V. 0 V. 60 V. TRUE ANSWER : ? YOUR ANSWER : ?
The principal of starting of 3 - Φ IM is similar to capacitor run IM. synchronous motor. repulsion motor type starting. transformer with short-circuited secondary. TRUE ANSWER : ? YOUR ANSWER : ?
A DC cumulatively compounded motor delivers rated load torque at rated speed. If the series field is short-circuited, then the armature current and speed will decrease and increase respectively both increase increase and decrease respectively both decrease TRUE ANSWER : ? YOUR ANSWER : ?
In an alternator the voltage generated per phase is proportional to flux per pole. number of turns in coil. frequency of waveform. All of these TRUE ANSWER : ? YOUR ANSWER : ?
In case of DC Shunt Motor electromagnetic torque developed is None of above. Inversely proportional to the armature current. Proportional to the armature current. Proportional to the square of armature current. TRUE ANSWER : ? YOUR ANSWER : ?
If s is the slip and f is the supply frequency of an induction motor, the frequency of rotor current is given by sf. sf / 2. f / s. s2. TRUE ANSWER : ? YOUR ANSWER : ?
In induction motor when the length of the air gap is increased, the magnetizing current of the motor increases while the short circuit current __________________. remains unchanged. decreased. kept constant to certain value. increased. TRUE ANSWER : ? YOUR ANSWER : ?
A separately-excited dc motor has an armature resistance of 0.5 Ω. It runs off a 250 V dc supply Drawing an armature current of 20 A at 1500 rpm. The torque developed for an armature current Of 10 A, for the same field current, will be 15.6 Nm 15.28 Nm 16.55 Nm 15.92 Nm TRUE ANSWER : ? YOUR ANSWER : ?
The teeth in the armature of a DC machines are sometimes skewed. This is done to reduce hysteresis loss. copper loss. eddy electric current loss. vibrations. TRUE ANSWER : ? YOUR ANSWER : ?
In travelling cranes for swing action which motor is preferred? Capacitor type induction motors. AC slip ring IM. Reluctance motor. DC series motor. TRUE ANSWER : ? YOUR ANSWER : ?