Electrical Machines A commutator with a diameter of 50 cm rotating at 1000 rpm. For a brush width of 1.5 cm, find the time of commutation in ms. 0.573. 0.443. 0.512. 0.649. 0.573. 0.443. 0.512. 0.649. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines What are slot wedges in a DC machine made of? Silicon steel. Mild steel. Cast iron. Fibre. Silicon steel. Mild steel. Cast iron. Fibre. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The armature resistance of a permanent magnet dc motor is 0.8 Ohm. At no load, the motor draws 1.5 A from a supply voltage of 25 V and runs at 1500 rpm. The efficiency of the motor while it is operating on load at 1500 rpm drawing a current of 3.5 A from the same source will be 88.8%. 48.0%. 59.2%. 57.1%. 88.8%. 48.0%. 59.2%. 57.1%. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Which of the following machines have highest power factor with respect to magnetizing current? Any of the above. Semi closed slot type machine. Open slot type machines. Closed slot type machines. Any of the above. Semi closed slot type machine. Open slot type machines. Closed slot type machines. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A self-excited shunt generator fails to build up, because 1. the field circuit is open 2. The armature circuit is open 3. the residual magnetism is absent 4. The direction of rotation is wrong From these, the correct answer is 3 only 1, 3 1, 2 and 3 1, 2, 3 and 4 3 only 1, 3 1, 2 and 3 1, 2, 3 and 4 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines For standing a DC motor a starter is required because It starts the motor. it limits the speed of the motor. it limits the starting current to a safe value. None of these It starts the motor. it limits the speed of the motor. it limits the starting current to a safe value. None of these ANSWER DOWNLOAD EXAMIANS APP
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