Which of the following method of speed control of D.C. machine will offer minimum efficiency ?

Related Mcqs:

A three point starter is considered suitable for______________?

A. shunt motors B. shunt as well as compound motors C. shunt, compound and series motors D. all D.C. motors...

D.C. series motors are used______________?

A. where load is constant B. where load changes frequently C. where constant operating speed is needed D. in none of the above situations...

If a D.C. motor designed for 40°C ambient temperature is to be used for 50°C ambient temperature, then the motor_____________?

A. of lower H.P. should be selected B. of higher H.P. should be selected C. can be used for 50°C ambient temperature also D. is to be derated by a factor recommended by manufacturer and select the next higher H.P. motor...

The losses occurring in a D.C. generator are given below. Which loss is likely to have highest proportion at rated load of the generator ?

A. hysteresis loss B. field copper loss C. armature copper loss D. eddy current loss...

If the field winding resistance of a DC shunt motor is increases, its speed will____________?

If the field winding resistance of a DC shunt motor is increases, its speed will A. decreases B. increases C. remains same D. none of the above...