CRST Electrical Systems & Controls Flashcards
6 cards from real CRST practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 CRST Electrical Systems & Controls flashcards as text
What is the standard voltage for a single-phase residential refrigeration compressor in the US?
Answer: 115V or 230V
Single-phase residential refrigeration compressors in the US typically operate on 115V or 230V circuits.
What device protects a compressor motor from overheating by interrupting power when winding temperature is excessive?
Answer: Internal overload protector
An internal overload protector (thermal overload) senses motor winding temperature and opens the circuit to prevent damage from overheating.
In a refrigeration control circuit, what is the primary function of a thermostat?
Answer: Cycle the compressor on and off to maintain set temperature
The thermostat senses space or product temperature and cycles the compressor on and off to maintain the desired set point.
What type of capacitor provides an extra boost of starting torque for a PSC or CSCR compressor motor?
Answer: Start capacitor
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.
Which electrical test instrument is used to measure the insulation resistance of a compressor motor winding to ground?
Answer: Megohmmeter (megger)
A megohmmeter (megger) applies a high DC voltage to measure insulation resistance in megohms, detecting winding-to-ground faults.
What is the purpose of a crankcase heater on a refrigeration compressor?
Answer: Prevent refrigerant migration into the oil during off cycle
A crankcase heater keeps the compressor oil warm during the off cycle to prevent refrigerant from migrating and diluting the lubricant.