Which of the following properties a damping oil must possess ?
A. Must be a good insulator
B. Should be non-evaporating
C. Should not have corrosive action upon the metal of the vane
D. The viscosity of the oil should not change with the temperature
E. All of the above
Answer: Option E
This Question Belongs to Electrical Engineering >> Electrical Machine Design
D.C. machines designed with a large value of air gap length have
A. worst, ventilation
B. poor ventilation
C. better ventilation
D. none of the above
_________ electromagnets generally function as holding magnets.
A. Tractive
B. Portative
C. Either of the above
D. None of the above
By which of the following methods motor rating for variable load drives can be determined ?
A. Method of average losses
B. Equivalent current method
C. Equivalent torque method
D. Equivalent power method
E. All of the above
In direct cooled system using hydrogen both stator and rotor conductors are made
A. solid
B. hollow
C. perforated
D. any ofthe above
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