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HVAC/R > HVAC/R COMPRESSORS AND CAPACITORS > Flashcards

HVAC/R COMPRESSORS AND CAPACITORS Flashcards

1
Q

Run Capacitor

A

In the circuit, always
Improves running efficiency

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2
Q

Start Capacitor

A

In the circuit for a few seconds
Start relay cuts it out after reaching 75% speed
Provides starting torque

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3
Q

Cheapest motor

A

RSIR RESISTIVE START INDUCTION RUN

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4
Q

RSIR AD CSIR

A

Start winding doesn’t stay in the circuit

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5
Q

PSC motor

A

Has no start relay

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6
Q

Most hermetic compressors

A

Respond to heat and current
So they are Inherent

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7
Q

Devices used for defrost

A

Pressure-operated method
See constant cut in
See dixell controllers
Frost sensors defrost on demand
Brine spray defrost
KOOL gas like reverse cycle hot gas

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8
Q

Coolers

A

Fan never turns off

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9
Q

Freezers

A

Fans turn off in the off cycle

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10
Q

Type of mechanical compressors failure

A

Lubrication
Flooding and slugging
Flooded start
Over heating

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11
Q

Lack of Lubrication causes

A

Damage to bearings that support crankshaft

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12
Q

Lubrication problems

A

Too much oil: can cause noise and vibration
Someone added too much oil
Too much oil from multiple compressor changes
Look for signs of slugging but with oil accumulated in the piston area

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13
Q

Too little oil in the compressor

A

Can seize because of friction between metal parts

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14
Q

Too little oil causes?

A

*Low refrigerant charge or low load not returning oild
*improper installation
*no defrost or frozen evap
* short cycling

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15
Q

Flooding

A

Is a continous stream of liquid refrigerant returning to the compessor

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16
Q

Flooding what to look for

A

Center and rear bearings worn or seize
Dragging rotor, shorted stator
Progressively scored shaft

17
Q

Fixed metering devices

A

Are critically charged means manufacturer has set an exact amount of refrigerant to be in the unit and hermetic compressors used mostly in critically charged systems

18
Q

PSC and CSCR

A

Keep the start winding in the circuit at all times

19
Q

CSIR AND RSIR

A

Remove start winding after it gets up to 2/3 RPM

HVAC/R (3 decks)

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