DC Motors

What kind of machine is this:

• Single phase AC shunt wound motor

• Series wound DC generator

• Shunt wound DC motor

• Compound DC motor

The rotation direction of a series wound DC motor can be changed by:

• Swapping the slip ring connections

• Reversing the shunt windings

• Swapping the shunt and series windings

• Reversing the field windings or the armature windings.

What kind of machine is this:

• Single phase AC series wound motor

• Series wound DC motor

• Shunt wound DC motor

• Compound DC motor

Which one of the following motors is likely to race up to dangerously high speed if it is run with no load?

• DC series wound motor

• AC double-cage induction motor

• DC shunt motor

• AC synchronous motor

What type of starter circuit is shown here?

• autotransformer

• variable frequency drive

• resistance starter

• 'soft start' starter

A 1 hp separately-excited DC motor has 0.5 ohm resistance and connected to a DC voltage of 150 V. Determine its armature current. Note, 1 hp is equal to 746 W.

• 3 A

• 5 A

• 1.5 A

• 6.5 A

A 1 hp separately-excited DC motor has 0.5 ohm resistance and connected to a DC voltage of 150 V. Determine the back-EMF in the armature. Note, 1 hp is equal to 746 W.

• 150 V

• 152.5 V

• 147.5 V

• 130 V

A shunt DC motor has 0.5 ohm armature resistance and 120 ohm field resistance. The motor is connected to a DC voltage of 120 V. Determine field winding current.

• 0.5 A

• 1 A

• 0.95 A

• 1.1 A

A shunt DC motor has 0.5 ohm armature resistance and 120 ohm field resistance. The motor draws 40 A when it is connected to a DC voltage of 120 V. Determine voltage induced in armature or back-EMF.

• 100 V

• 120 V

• 140 V

• 80 V

A 5 hp shunt DC motor has 0.5 ohm armature resistance and 120 ohm field resistance. The motor is connected to a DC voltage of 120 V. Determine its back-emf. Note, 1 hp is equal to 746 W.

• 100.5 V

• 110.5 V

• 125.5 V

• 104.5 V