Electrical Machines In a 3 - Φ IM with line frequency f1 and winding factor kw1 and kw2 for stator and rotor respectively the ratio of per phase stator winding emf E1 to per phase rotor winding emf E2 at standstill is given by E1 / E2 = N1kw1 / N2kw2. E1 / E2 = 1. E1 / E2 = f1kw1 / f2kw2. E1 / E2 = N1 / N2. E1 / E2 = N1kw1 / N2kw2. E1 / E2 = 1. E1 / E2 = f1kw1 / f2kw2. E1 / E2 = N1 / N2. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Copper brushes in DC machine are used None of these in both of above cases. where high voltage and low current. where low voltage and high currents are involved. None of these in both of above cases. where high voltage and low current. where low voltage and high currents are involved. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines If the temperature of armature resistance is increased, the speed of a series motor would decrease. None of above. increase. not change. decrease. None of above. increase. not change. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The field system of an alternator is usually excited 250 / 250 V DC. 110 / 220 V AC. 230 V AC. 3 - Φ, 50 Hz and 400 V. 250 / 250 V DC. 110 / 220 V AC. 230 V AC. 3 - Φ, 50 Hz and 400 V. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The use of double squirrel cage winding on the rotor provides a large starting torque. reduced starting torque. low noise. higher efficiency. a large starting torque. reduced starting torque. low noise. higher efficiency. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Consider the following statements regarding the speed control of dc motors : 1. ward-leonard method is suitable forconstant-torque drives 2. Ward-leonard method is suitable for constant-power drives 3. field-control method facilitates speed control below base speed 4. Armature-resistance control method is more efficient than ward-leanard method 5. Field-control method is suitable for constant-torque drives 6. Armature-resistance control method is suitable for constant-torque drives From these, the correct answer is 1, 2, 5 1, 2, 6 1, 3, 5 1, 4, 6 1, 2, 5 1, 2, 6 1, 3, 5 1, 4, 6 ANSWER DOWNLOAD EXAMIANS APP
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