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%.

EE MCQ

Home
Quiz
Contact Us

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%.

72.5%

67.5%

78.5%

82.5%

72.5%

67.5%

78.5%

82.5%

In a 3-phase induction motor, torque and supply voltage are related as

T ∝ 1/V

T ∝ 1/V²

T∝ V²

T ∝ V

T ∝ 1/V

T ∝ 1/V²

T∝ V²

T ∝ V

Electrical Machines

Slip test is performed to determine

All of these

slip

direct axis reactance and quadrature axis reactance

positive sequence reactance and negative sequence reactance

All of these

slip

direct axis reactance and quadrature axis reactance

positive sequence reactance and negative sequence reactance

Electrical Machines

Which of the following alternators contain large number of poles?

Aame in both alternators.

Turbo alternators.

Hydro alternators.

None of these

Aame in both alternators.

Turbo alternators.

Hydro alternators.

None of these

Electrical Machines

A 400 V, 50 Hz, 30 Hp, three phase IM is drawing 50 A current at 0.8 p.f lagging. The stator and rotor copper losses are 1.5 KW and 900 W respectively. The friction and windage losses are 1050 W and core losses are 1200 W. The air gap power of the motor will be

26.21 kW.

24.11 kW.

25 kW.

23.06 kW.

26.21 kW.

24.11 kW.

25 kW.

23.06 kW.

Electrical Machines

DC motors are stopped by opening line switches and not by forcing the handle of the motor starter back to OFF position. This is due to occurance of

None of these.

Both of above.

Heavy sparking at the first stud of starting resistance steps.

Heavy sparking at brushes.

None of these.

Both of above.

Heavy sparking at the first stud of starting resistance steps.

Heavy sparking at brushes.

Google

Download our application

Android

Apple

Facebook

Instagram

Home
Quiz
Privacy Policy
Disclaimer
Terms & Conditions
Contact Us

EE MCQ

Get the current of knowledge

Support email : eemcq@yahoo.com

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%.

In a 3-phase induction motor, torque and supply voltage are related as

Slip test is performed to determine

Which of the following alternators contain large number of poles?

A 400 V, 50 Hz, 30 Hp, three phase IM is drawing 50 A current at 0.8 p.f lagging. The stator and rotor copper losses are 1.5 KW and 900 W respectively. The friction and windage losses are 1050 W and core losses are 1200 W. The air gap power of the motor will be

DC motors are stopped by opening line switches and not by forcing the handle of the motor starter back to OFF position. This is due to occurance of

Google

Android

Apple

Facebook

Telegram

Instagram