Electrical Machines The commutator segments of DC machines are made up of copper alloy brass copper hard-drawn copper copper alloy brass copper hard-drawn copper ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Which of the following factors improve commutation in a dc machine ? 1. High contact resistance of brushes 2. High inductance of the coils undergoing commutation 3. Shifting of brushes in the direction of rotation for a generator and in the opposite direction For a motor 4. Narrow width for the commutation bars Select the correct answer using the codes given below : Codes : 1 and 3 1, 2 and 4 2, 3 and 4 1, 2, and 3 1 and 3 1, 2 and 4 2, 3 and 4 1, 2, and 3 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The direction of rotation of a DC motor can be determined by Fleming's right hand rule. Lenz's law. Ampere's law. Fleming's left hand rule. Fleming's right hand rule. Lenz's law. Ampere's law. Fleming's left hand rule. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A 220 V DC machine has an armature resistance 1Ω. If the full load current is 20 A, the difference of induced voltage and generator is 0 V. 20 V. 40 V. 60 V. 0 V. 20 V. 40 V. 60 V. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In case of a dc motor the ratio Eb / E is indicative of ratio of starting to running current. ratio of starting to running torque. ratio of input to output voltage. efficiency. ratio of starting to running current. ratio of starting to running torque. ratio of input to output voltage. efficiency. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A large series motor is never started without some mechanical load on it because otherwise it will develop excessive speed and damage itself. open fuse or circuit breaker. produce sparking at brushes. draw too much current. develop excessive speed and damage itself. open fuse or circuit breaker. produce sparking at brushes. draw too much current. ANSWER DOWNLOAD EXAMIANS APP
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