Electrical Machines DC motors are stopped by opening line switches and not by forcing the handle of the motor starter back to OFF position. This is due to occurance of Heavy sparking at the first stud of starting resistance steps. Heavy sparking at brushes. Both of above. None of these. Heavy sparking at the first stud of starting resistance steps. Heavy sparking at brushes. Both of above. None of these. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Consider the following statements about commutating poles which are fitted on most large dc Shunt motors: 1. The commutating poles are placed in the geometric neutral plane and their number is usually Equal to the number of main poles 2. The winding on the commutating poles is connected in series with the shunt-field winding on the main poles 3. The polarity of the commutating pole must be that of the next pole further ahead 4. The commutating poles neutralize the reactance voltage produced in the coil undergoing Commutation. Of these statements, 1, 2 and 4 are correct 1 and 4 are correct 2, 3 and 4 are correct 1, 2 and 3 are correct 1, 2 and 4 are correct 1 and 4 are correct 2, 3 and 4 are correct 1, 2 and 3 are correct ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A 220 V, DC shunt motor is operating at a speed of 1440 rpm. The armature resistance is 1.0 Ω and armature current is 10 A. of the excitation of the machine is reduced by 10%, the extra resistance to be put in the armature circuit to maintain the same speed and torque will be 2 .1 Ω 1.8 9 Ω 3.1 Ω 1.79 Ω 2 .1 Ω 1.8 9 Ω 3.1 Ω 1.79 Ω ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The overall power factor of an on load transformer depends on the power factor of the load. is always unity. is always leading. is always lagging. depends on the power factor of the load. is always unity. is always leading. is always lagging. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Slot wedges in a dc machine is made up of silicon steel. mild steel. cast iron. fibre. silicon steel. mild steel. cast iron. fibre. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In a synchronous generator with constant steam input supplies power to an infinite bus at a lagging power factor. If the excitation is increased power angle decrease and power factor increase power angle increase and power factor decrease both power angle and power factor increase both power angle and power factor decrease power angle decrease and power factor increase power angle increase and power factor decrease both power angle and power factor increase both power angle and power factor decrease ANSWER DOWNLOAD EXAMIANS APP
EXAMIANS