Single Phase Motors Flashcards
1
Q
What’s a RSIR motor?
(Resistive start induction run)
A
- small inexpensive up to 1/3 HP
- no capacitors
- usually in hermetic compressors comes with a current relay, plugs on
- very low starting torque, no start cap
- removes start winding from circuit when motor reaches 75 % of its full speed
- must equalize quickly
2
Q
What’s a CSIR motor?
(Capacitor start induction run)
A
- Found in hermetic and semi hermetic compressors
- Comes with current relay or potential relay
- Fractional HP up to 3/4 hp
- Has a start cap but no run cap
- higher starting torque
- Can be used on TXV system, does not need to equalize, pump down system
3
Q
What is a CSCR motor?
(Capacitor start capacitor rub, also known as duel cap)
A
- highest starting torque, good electrical efficiency
- Up to 5 HP
- Found on larger compressors, semi hermetic
- Comes with potential relay
- Start winding and run winding stays in the circuit but start cap comes out
- Caps in parallel
4
Q
What are PSC motors?
(Permanent split motors)
A
- Start winding stays in
- Has a run cap
- No start relay, start winding stays in
- no start cap
- no starting torque
- low running current and good speed control
5
Q
What is a shaded pole motor?
A
- also known as a squirrel cage motor
- low torque in the start and low current draw In the run cycle
- uses magnetic poles to operate
