Electrical Machines Objective Questions – Set 7

Direct-on-line (DOL) starters are not suitable for starting large DC motors, because

High inrush of current during a starting of a DC motor can efficiency be restricted to a safer value by increasing the _________________ resistance.

The current drawn by a DC motor at the time of starting is

The armature voltage control is considered suitable for a DC motor driven at constant

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

Two DC series motor are connected in series and are driving the same mechanical load. If the motors are now connected in parallel the speed will become

Which of the following DC Motor requires 3 point starter?

Field divertor method of speed control of a DC series motor gives speed above rated one due to reduction of

When two DC series motors are connected in parallel, the resultant speed is

If an additional resistance is connected in series with a DC series motor operating at rated speed, the speed of the motor will

In case of DC Shunt Motor, the speed will____ if the voltage increases, neglecting armature saturation.

In which of the following DC Motor the ratio of starting torque to full load torque is minimum?

The main disadvantage(s) of the ward-Leonard system is/are

For a given torque, reducing divertor resistance of a DC series motor

The field divertor resistance for a DC series motor is of order of

In which of the following speed control of DC motor the speed obtained is below than the rated speed?

If starter is not used with large DC motor for starting, it will

If the handle of a three point starter goes to back to OFF position, it may due to

To get the speed of DC motor is more than normal without wastage of electrical energy _____________ is used.

If the no-voltage release in a DC motor starter fails to operate on failure of supply, on resumption of supply the motor will

Neglecting all losses, the developed torque (T) of DC separately excited motor, operating under constant terminal voltage is reduced to its output power (P) as

Which DC motor will have least percentage increase of input current, for the same percentage increase in the torque

In a DC Motor 3 point starter is used

In a seperately excited DC Motor if field current is increased, it will

Variation in speed by ward-Leonard control of DC motors occurs due to variation in

For starting a DC motor a starter is required because

A DC series motor is running with a divertor connected across its field winding. If the divertor resistance is reduced then the speed of the motor will

Which of the following DC Motor use 4-point starter?

Ward Leonard control is provides speed control

In speed control of DC Series motor, speed lower than the rated speed can be obtained by