Electrical Machine Design

This is an MCQ-based quiz on Electrical Machine Design.

This includes Corrugations, Fins, Tubes, Duplex winding, Triplex winding, Forced winding, Main poles, Interpoles, and Frame.

Start Quiz

_________ electromagnets generally function as holding magnets.

Tractive Portative Either of the above None of the above

By which of the following methods motor rating for variable load drives can be determined ?

Method of average losses Equivalent current method Equivalent torque method Equivalent power method All of the above

On which of the following variables heat convected depends ?

Power density Temperature difference between heated surface and coolant Thermal resistivity, density, specific heat Gravitational constant All of the above

By which of the following methods the temperature rise of windings and other parts may be determined?

Thermometer method Resistance method Embedded temperature detector method Any of the above

In induction motors, the length of air gap in kept as small as mechanically possible is order to have

Low power factor High power factor High over load capacity Any of the above

The high voltage winding is usually which of the following type?

Cylindrical winding with circular conductors Crossover winding with either circular or small rectangular conductors Continuous disc type winding with rectangular conductors All of the above types

Disc windings are primarily used in

Short capacity transformers Medium capacity transformers High capacity transformers Any of the above

Which of the following brushes can be used for high values of current density?

Metal graphite brushes Hard carbon brushes Electro-graphitic brushes Natural graphite brushes

The surge phenomenon is particularly important in case of

Low voltage transformers Medium voltage transformers High voltage transformers Any of the above

For 275 kV transformers, using cold rolled grain oriented steel, which of the following values of flux density may be used?

1.0 Wb/m2 1.1 Wb/m2 1.3 Wb/m2 1.6 Wb/m2

The distance between the starts of two consecutive coils measured in terms of coil sides is called

Front pitch Winding pitch Commutator pitch Back pitch

_________is extensively used for those portions of magnetic circuit which carry steady flux and need superior mechanical properties?

Grey cast-iron Cast steel High carbon steel Stainless steel

_________ brushes are fragile and cause excessive wear of commutator,

Natural graphite Hard carbon Electro graphitic Metal graphite

Which of the following in an application of D.C. motors?

Traction Drives for process industry Battery driven vehicles All of the above

The voltage control in electric supply networks in required on account of which of the following reasons?

Adjustment of voltage at consumers premises within statutory limits Control of active and reactive power Adjustment of short period daily and seasonal voltage variations in accordance with variations of load All of the above

The cold rolled grain oriented steel has _________ permeability in the direction of the grain orientation.

Minimum Maximum Nil None of the above

D.C. machines designed with a large value of air gap length have

Worst Ventilation

Poor Ventilation

Better Ventilation

None of the above

In direct cooled system using hydrogen both stator and rotor conductors are made

Solid

Hollow

Perforated

Any of the above