Millwright Certification Electrical Systems and Controls 2

Question 1

What is the purpose of a control transformer in an industrial motor control panel?

Accepted Answer

To step down line voltage to a safe level for control circuit devices

Answer

To boost line voltage for high-inertia motor starting

Answer

To convert three-phase power to single-phase for control components

Answer

To provide uninterruptible backup power during outages

Question 2

Which device uses a small coil current to electromagnetically operate contacts that switch a larger load circuit?

Accepted Answer

Control relay (pilot relay)

Answer

Thermal overload relay

Answer

Inductive proximity sensor

Answer

Current transformer

Question 3

What does PLC stand for in industrial automation and control systems?

Accepted Answer

Programmable Logic Controller

Answer

Power Line Converter

Answer

Pneumatic Load Controller

Answer

Parallel Logic Circuit

Question 4

When performing lockout/tagout (LOTO) on electrical equipment, what is the FIRST step a millwright must complete?

Accepted Answer

Identify all energy sources associated with the equipment

Answer

Apply the lockout hasp to the disconnect switch

Answer

Notify affected employees that equipment will be shut down

Answer

Test equipment with a voltmeter to verify de-energization

Question 5

What is the key difference between a normally open (NO) and a normally closed (NC) contact in a relay?

Accepted Answer

NC contacts pass current at rest; NO contacts pass current only when energized

Answer

NO contacts pass current at rest; NC contacts pass current only when energized

Answer

Both pass current at rest but differ in their current-carrying capacity

Answer

NO contacts are for AC circuits; NC contacts are used only in DC circuits

Question 6

What is the function of a limit switch in an automated industrial system?

Accepted Answer

To detect the physical position of a machine component and signal the control system

Answer

To limit the maximum current draw of a motor to its nameplate rating

Answer

To limit conveyor belt speed to a preset maximum

Answer

To protect the control circuit from voltage surges and spikes

Question 7

Which type of single-phase motor uses a capacitor in series with the auxiliary winding to develop adequate starting torque?

Accepted Answer

Capacitor-start induction-run motor

Answer

Shaded pole motor

Answer

Split-phase resistance-start motor

Answer

Wound rotor induction motor