Electrical Machines Which of the following represents the pitch factor? sin (α/2) Cos (α/2) Cos α Cos α² sin (α/2) Cos (α/2) Cos α Cos α² ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The field system of an alternator is usually excited 250 / 250 V DC. 110 / 220 V AC. 3 - Φ, 50 Hz and 400 V. 230 V AC. 250 / 250 V DC. 110 / 220 V AC. 3 - Φ, 50 Hz and 400 V. 230 V AC. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The following statements relate to compensating winding (CW) and interpole winding (IW) of a dc machine : 1. CW neutralizes the armature reaction under a pole pitch 2. IW is connected in series with armature circuit 3. IW produces mmf in the commutating zone only 4. CWmmf is directed along the brush axis 5. Mmf produced by IW is equal to armature mmf From these, the correct statements are 2, 3, 4, 5 1, 3, 4, 5 2, 3, 4 1, 2, 3, 4 and 5 2, 3, 4, 5 1, 3, 4, 5 2, 3, 4 1, 2, 3, 4 and 5 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The direction of generated emf in the armature coil of a DC machine is 1. the same as that of the current in a generator 2. the same as that of the current in a motor 3. opposite to that of the current in a generator 4. opposite to that of the current in a motor From these, the correct answer is 2, 3 1, 3 2, 4 1, 4 2, 3 1, 3 2, 4 1, 4 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A DC shunt machine generates 250 V on open circuit at 1000 RPM. Armature resistance is 0.5 Ω, field resistance 250 Ω. When running as a motor takes 4 A at 250 V. Calculate the efficiency when running as a motor taking 40 A at 250 V. Armature reaction weakens the field by 4%. 82.5% 72.5% 67.5% 78.5% 82.5% 72.5% 67.5% 78.5% ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Two mechanically coupled alternators deliver power at 50 Hz and 60 Hz respectively. Highest speed of alternator is 3600 rpm. 600 rpm. 3000 rpm. 500 rpm. 3600 rpm. 600 rpm. 3000 rpm. 500 rpm. ANSWER DOWNLOAD EXAMIANS APP
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