Controls Flashcards
The run windings of a motor have _____ turns as compared to the start windings.
fewer
On a typical split-phase electric motor the start winding circuit is deenergized as it reaches approximately ____ of its operating speed?
75%
What component wired in series with the start windings on a single phase motor will create greater starting torque.
a capacitor
A three-phase motor does not have
A. start windings
B. a start capacitor
C a start relay
A start component that is rated in microfarad would be a
capacitor
What effect will a higher supply voltage have on the current draw of an electric motor?
it will be higher than it should be
With an electric motor running normally the amperage reading would be called?
run-load amperage
If a technician uses an ohm meter to check the windings of an electric motor and records an infinite reading on the start windings this would indicate?
the start winding circuit has an open somewhere
What device would be discharged using a 20,000-ohm, 5 watt resistor?
capacitor
The run-load amperage on an electric motor is typically
1/5 that of a full-load amperage
What device is used to energize another load such as a contactor or motor starter with in turn would start or stop a motor.
a pilot duty relay
A magnetic coil and electrical contacts are the primary components of this electrical device?
a contactor
A magnetic coil, overload protector and electrical contactors are the primary components of this electrical device
a motor starter
An electric motor that has an internal overload would have a?
a thermal device buried in the motor windings
What device could be used as external protection for a motor?
A. a line fuse
B. a circuit breaker
C. an external overload
What type of motor would a technician switch any two legs on to reverse the rotation of the motor?
Three Phase
A technician could install this type of component on a refrigeration system that has multiplexed circuits to
prevent the evaporator temperature on a multiplexed system from falling too low
A technician would set this device by the RLA on the refrigeration compressors
crankcase pressure regulator
A technician would set this device by calculating the evaporator superheat
thermal expansion device
What device is used to reduce the suction temperature of the compressor?
desuperheating TXV
If a technician needs to control the head pressure on a refrigeration unit within tight limits the best device to employ on the condenser fan motor would be?
a variable frequency drive (VFD)
The EPR valve is installed between the?
suction accumulator and the compressor
and
evaporator and the suction accumulator
Which of these devices would be considered a low ambient temperature head pressure control used on an outdoor unit?
fan cycling
If a technician wanted to protect a refrigeration system from operating
under excessive head pressure situations he would install a/an
head pressure control
The following device would use a pressure transducer to sense net oil pressure, electronic oil safety controllers use a
electronic oil safety control
If a technician needed high accuracy it would be best to select a device
that employed the following sensing element if available
a thermistor
If a technician installed a low-pressure switch, a liquid line solenoid valve, and a thermostat in a
refrigeration system what kind of circuit would have been designed?
automatic pump down cycle
