CRST CRST Electrical Systems & Controls

Question 1

What is the standard voltage for a single-phase residential refrigeration compressor in the US?

Accepted Answer

115V or 230V

Answer

Single-phase residential refrigeration compressors in the US typically operate on 115V or 230V circuits.

Question 2

What device protects a compressor motor from overheating by interrupting power when winding temperature is excessive?

Accepted Answer

Internal overload protector

Answer

An internal overload protector (thermal overload) senses motor winding temperature and opens the circuit to prevent damage from overheating.

Question 3

In a refrigeration control circuit, what is the primary function of a thermostat?

Accepted Answer

Cycle the compressor on and off to maintain set temperature

Answer

The thermostat senses space or product temperature and cycles the compressor on and off to maintain the desired set point.

Question 4

What type of capacitor provides an extra boost of starting torque for a PSC or CSCR compressor motor?

Accepted Answer

Start capacitor

Answer

A start capacitor provides a high momentary capacitance to boost starting torque and is switched out of the circuit once the motor reaches operating speed.

Question 5

Which electrical test instrument is used to measure the insulation resistance of a compressor motor winding to ground?

Accepted Answer

Megohmmeter (megger)

Answer

A megohmmeter (megger) applies a high DC voltage to measure insulation resistance in megohms, detecting winding-to-ground faults.

(CRST) Certified Refrigeration Service Technician Practice Test

(CRST) Certified Refrigeration Service Technician Practice Test

CRST CRST Electrical Systems & Controls