Electrical Machines For successful parallel operation of two single phase transformers, the most essential condition is that their polarities are properly connected KVA ratings are equal percentage impedances are equal turn- ratios are exactly equal polarities are properly connected KVA ratings are equal percentage impedances are equal turn- ratios are exactly equal ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A voltmeter gives 120 oscillations per minute when connected to the rotor of an induction motor. The frequency is 50Hz. The slip of the motor is 2% 4% 5% 25% 2% 4% 5% 25% ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A commutator in DC machines can 1. provide half-wave rectification 2. Provide full-wave rectification 3. convert ac to dc 4. Convert dc to ac 5. provide controlled full-wave rectification From these, the correct answer is 2, 3, 4 2, 3, 4, 5 1, 2, 3 2, 3 ,5 2, 3, 4 2, 3, 4, 5 1, 2, 3 2, 3 ,5 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A 3 - Φ, 400 / 200 V, Y - Y connected wound rotor induction motor has 0.06 Ω rotor resistance and 0.3 Ω standstill reactance per phase. To make the starting torque equal to maximum torque of the motor the additional resistance required 0.45 Ω. 0.78 Ω. 0.66 Ω. 0.24 Ω. 0.45 Ω. 0.78 Ω. 0.66 Ω. 0.24 Ω. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Which of the following is/are the advantages of carbon brush over the copper brush? They are not hard as copper brush They are self lubricating in nature All of these In case of any sparking they will be less damaged than copper brushes They are not hard as copper brush They are self lubricating in nature All of these In case of any sparking they will be less damaged than copper brushes ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A short-shunt cumulatively-compounded dc generator builds up a voltage of 220 V at no load at rated speed. If it is operated as a differentially compounded generator, other things remaining the same, it would build up 220 V more than 220 V somewhat less than 220 V 6 V 220 V more than 220 V somewhat less than 220 V 6 V ANSWER DOWNLOAD EXAMIANS APP
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