CEP Motor Control & Drive Systems

Question 1

What is the primary function of a motor control center (MCC)?

Accepted Answer

To centralize motor starting, stopping, and protection equipment in one assembly

Answer

To provide centralized lighting control

Answer

To convert AC power to DC for motor loads

Answer

To regulate voltage for sensitive electronic equipment

Question 2

A reduced-voltage soft starter controls motor starting by:

Accepted Answer

Gradually ramping up the voltage applied to the motor terminals

Answer

Reducing the supply frequency during startup

Answer

Adding external resistance in series with the stator

Answer

Switching motor windings from star to delta configuration

Question 3

A variable frequency drive (VFD) controls AC motor speed by varying:

Accepted Answer

Both output frequency and voltage simultaneously

Answer

Voltage only, keeping frequency constant

Answer

Current only, through a series impedance

Answer

Power factor of the supply current

Question 4

The purpose of overload relays in a motor starter is to:

Accepted Answer

Protect the motor from sustained overcurrent caused by mechanical overloading

Answer

Protect the circuit against short-circuit faults

Answer

Limit the motor starting current during acceleration

Answer

Provide protection against single-phasing during starting only

Question 5

According to NEMA standards, a Size 1 motor starter has a maximum continuous current rating of:

Accepted Answer

27 amperes

Answer

9 amperes

Answer

18 amperes

Answer

45 amperes

Question 6

Which starting method provides the highest starting torque for an AC induction motor?

Accepted Answer

Across-the-line (full voltage) starting

Answer

Part-winding starting

Answer

Star-delta (wye-delta) starting

Answer

Autotransformer reduced-voltage starting

Question 7

Which NEC article governs the installation requirements for motors, motor branch circuits, and motor controllers?

Accepted Answer

Article 430

Answer

Article 240

Answer

Article 445

Answer

Article 460