Electrical Engg (EEE) - MCQ Practice Questions

A separately excited DC motor runs at 1000 rpm at rated load with an armature voltage of 200 V and armature current of 20 A. If the armature resistance is $1\Omega$, what is the back EMF of the motor?

In a Variable Frequency Drive (VFD) controlling an induction motor, the V/f ratio is kept constant primarily to:

A DC shunt motor has an armature resistance of $0.5\Omega$ and a field resistance of $200\Omega$. It is connected to a $220\text{V}$ supply. If the armature current at full load is $40\text{A}$, the developed mechanical power is:

In a three-phase induction motor drive, the slip at maximum torque is denoted by $s_m$. If the rotor resistance per phase is $R_2$ and the rotor leakage reactance per phase at standstill is $X_2$, then $s_m$ is given by:

Which of the following methods of speed control of a DC shunt motor gives speed below the base (rated) speed?

In regenerative braking of a DC separately excited motor, the motor acts as a:

A squirrel cage induction motor is to be started using a star-delta starter. Compared to direct-on-line (DOL) starting, the starting torque with star-delta starting is:

In a chopper-controlled DC drive, a DC motor is supplied from a 200 V source through a chopper with a duty cycle of 0.6. Assuming continuous current conduction, the average output voltage applied to the motor armature is:

The torque-speed characteristic of a fan or centrifugal pump type load follows the relationship:

In vector (field-oriented) control of an induction motor, the stator current is resolved into two decoupled components. These components are responsible for: