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

208V or 460V

Answer

480V or 600V

Answer

24V or 48V

Question 2

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

Accepted Answer

Internal overload protector

Answer

Crankcase heater

Answer

Start capacitor

Answer

Run capacitor

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

Regulate refrigerant flow rate

Answer

Control fan motor speed

Answer

Measure system pressure

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

Run capacitor

Answer

Film capacitor

Answer

Electrolytic capacitor

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

Clamp-on ammeter

Answer

Digital multimeter

Answer

Oscilloscope

Question 6

What is the purpose of a crankcase heater on a refrigeration compressor?

Accepted Answer

Prevent refrigerant migration into the oil during off cycle

Answer

Heat the suction line to prevent liquid slugging

Answer

Warm the discharge gas before it enters the condenser

Answer

Preheat the motor windings before start-up