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单选题
When a refrigeration compressor motor fails to start, the FIRST thing that should be checked for is a （）.
A
loose expansion valve control bulb
B
low differential setting on the H-Pcutout
C
blown fuse in the motor circuit
D
faulty suction pressure regulator
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If the refrigeration compressor crankcase is sweating, the cause may be due toA.a shortage of refrigerantB.the compressor running continuouslyC.liquid refrigerant returning to the compressorD.the compressor short cycling on the high pressure cutout
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Excessive oil foaming in the crankcase of a refrigeration compressor is most likely to occur when the compressorA.has run continuously for a long periodB.suction pressure is below normalC.oil level is below normalD.starts after a long idle period
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Sweating of the refrigeration system compressor crankcase is caused by_______ .A.too much superheatB.insufficient superheatC.suction pressure too lowD.excessive refrigerant returning to the compressor
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If the suction pressure for an operating refrigeration compressor is below normal, the cause may be ______.A.an excess of liquid refrigerantB.the expansion valve overfeedingC.a fouled compressor suction strainerD.the compressor short cycling
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单选题Low compressor head pressure in a refrigeration system can be caused by（）.A
insufficient condenser cooling waterB
excessive condenser cooling waterC
air in the refrigeration systemD
excessive refrigerant in the system
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单选题If an electric motor driven air compressor fails to start, it may be due to a （）.A
leaking discharge valveB
jammed suction valveC
tripped overload relayD
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单选题When liquid reaches the compressor of a refrigeration system through the suction line, the condition is called （）.A
flooding backB
superheatingC
overflowingD
recycling
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单选题Excessive oil foaming in the crankcase of a refrigeration compressor can result in （）.A
overheated compressor bearingsB
excess lube oil viscosityC
carbon deposits on the compressor piston ringsD
wax crystals forming in the lubricant
考题
单选题The unloading system on an air compressor will （）.A
increase compressor discharge pressure on demandB
increase compressor operating speed as necessaryC
allow the motor to turn the compressor opposed only by frictionD
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单选题When adding oil to a refrigeration system, precautions must be taken to ensure that （）.A
the compressor suction pressure is not too highB
all air is purged from the pump and charging fittingsC
the high pressure cutout switch is held open to prevent accidental startingD
the condenser is completely shutdown first
考题
单选题操作完后，关掉电动机。（）A
After operation, start the electric motor.B
Before operation, stop the electric motor.C
Before operation, start the electric motor.D
After operation, stop the electric motor.
考题
单选题If a refrigeration compressor is running continuously without lowering the temperature in the refrigerated space, the trouble may be （）.A
a shortage of compressor oilB
warm food in the refrigeratorC
excessive condenser cooling waterD
a shortage of refrigerant
考题
单选题（）are supplied by main switchboard directly.A
Suez Canal searchlight, air compressor and air conditioning compressorB
Air compressor, boiler blower and refrigeration plantC
Boiler blower, Suez Canal searchlight and refrigeration plantD
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考题
单选题If a refrigeration compressor will not start, the reason may be （）.A
the pressure regulating valve is not closingB
an excessive lack of refrigerant in the systemC
badly leaking discharge valvesD
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单选题When a refrigeration compressor is in the ‘off’ cycle, the thermal expansion valve will（）.A
always be wide open when the compressor restartsB
continue to operate as if the system were in operationC
remain open until evaporator pressure equalizes, then close until the compressor restartsD
always be completely closed until the compressor restarts
考题
单选题If the electric motor driving an air compressor fails to start, the cause may be a （）.A
leaking unloaderB
tripped circuit breakerC
control line leakD
defective pop valve
考题
单选题If the refrigeration compressor crankcase is sweating, the cause may be due to （）.A
a shortage of refrigerantB
the compressor running continuouslyC
liquid refrigerant returning to the compressorD
the compressor short cycling on the high pressure cutout
考题
单选题If the suction pressure at the refrigeration compressor is below normal, the cause can be（）.A
refrigerant overchargeB
overfeeding by the expansion valveC
a restricted suction strainerD
due to short cycling of the compressor
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单选题If the capacity of the refrigeration compressor is too large, the saturation temperature will （）.A
riseB
fallC
be maintained constantD
None of the above
考题
单选题Excessive oil foaming in the crankcase of a refrigeration compressor at start up can cause（）.A
compressor damage from improper lubricationB
refrigerant absorption by the lubricantC
increased viscosity in the lubricantD
carbon deposit on the compressor suction valves
考题
单选题In the refrigeration compressor the temperature of the vapor is （） by compression.A
raisedB
risenC
reducedD
maintained constant
考题
单选题It should be ensured that only （） vapor is handled by the refrigeration compressor.A
humidityB
dryC
steamD
oil
考题
单选题In the （） refrigeration compressor one end of the crank shaft extends through the crankcase house for connection, via a coupling or pulley, to an external drive motor.A
open-typeB
hermeticC
semi-hermeticD
all the above
考题
单选题The purpose of the refrigeration system low pressure cutout switch is to （）A
protect the compressor from liquid flood backB
protect the compressor from low discharge pressureC
start and stop the compressor upon system demandD
start the compressor after a drop in the evaporator pressure
考题
单选题Sweating of the refrigeration system compressor crankcase is caused by （）.A
too much superheatB
insufficient superheatC
suction pressure too lowD
excessive refrigerant returning to the compressor
考题
单选题When a refrigeration compressor has developed a high head pressure as a result of a refrigerant overcharge, you should （）.A
increase the amount of cooling water to the condenserB
decrease the amount of cooling water to the condenserC
add more refrigerant to the systemD
remove some refrigerant from the system
考题
单选题Excessive oil foaming in the crankcase of a refrigeration compressor is most likely to occur（） when the compressor.A
has continuously for a long periodB
suction pressure is below normalC
oil level is below normalD
starts after a long idle period
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