ITMC Motor Controls 2

Question 1

What is the purpose of an overload relay in a motor control circuit?

Accepted Answer

To protect the motor from excessive current due to mechanical overload

Answer

Overload relays monitor running current and trip the circuit if the motor draws excessive current from a mechanical overload, preventing winding damage.

Question 2

In a two-wire control circuit, what happens when the control switch is opened?

Accepted Answer

The motor stops and restarts automatically when the switch closes

Answer

Two-wire control uses a maintained contact device, so the motor restarts automatically when the control switch recloses without requiring a separate start button.

Question 3

Which component in a NEMA full-voltage starter provides low-voltage protection?

Accepted Answer

Holding contact (auxiliary contact)

Answer

The holding contact (auxiliary contact) seals in the coil circuit after the start button is released; loss of voltage drops the coil and opens the holding contact, preventing automatic restart.

Question 4

A motor control technician measures 0 V across the coil of an energized contactor. What is the most likely cause?

Accepted Answer

The coil is open-circuited

Answer

Zero voltage across an energized coil indicates the coil is open-circuited, preventing current flow and coil energization.

Question 5

What does a normally closed (NC) contact do when the relay coil is energized?

Accepted Answer

Opens to break the circuit

Answer

A normally closed contact is closed in the de-energized (normal) state and opens when the coil is energized, breaking the circuit.

(ITMC) Industrial Technology Maintenance Certification Practice Test

(ITMC) Industrial Technology Maintenance Certification Practice Test

ITMC Motor Controls 2