18 Flashcards
Provides 230V and can have a center tapped leg to furnish 115V. Also has one useable
voltage of 185V from L3 to ground.
Delta transformer connection
Tabs or studs on the end of small motor housing.
End mount
Number of Either 2-wire power (single) or 3-wire power (three)
Phase
The current the motor is drawing at its service factor loading.
Service factor amps
The action of a vertical fan shaft that pushes air up is actually pushing the shaft downward. The load on the end of the bearing needs an additional surface to absorb the push.
Thrust surface
A cradle fits the motor end housing at each end and the end housing is held down with
a bracket.
Cradle motor mount
Rubber isolating motor mounts used to reduce noise from the metal framework of the
system.
Resilient motor mount
Normally used with fans, pumps and compressors. Some type of coupling must be installed between the motor and driven device.
Direct drive motor
“Y” or star shaped connection with three windings going to a center tap (neutral or
grounded leg)
Wye transformer connection
A strap that wraps around the motor to secure it with brackets mounted to the strap.
Belly band mount
Reserve horsepower
Motor service factor
Sealed motor for use in fuel vapor environments.
Explosion proof motor
Mount fastened to the motor body.
Rigid motor mount
Mathematical calculation used to get UL approval for a compressor motor.
Rated load amperage
Grounding straps are required on resilient mounted motors to ____.
ground the motor in case of a winding failure
If the voltage supplied to the motor is well below the motor’s rated voltage, the current draw will be______ it should be.
Higher than
Determine the fan blower speed if the motor speed is 3600 pm with a drive pulley diameter of 4 inches. The blower shaft has a 6 inch pulley attached to it.
2400 rpm
The temperature of the motor casing is typically cooler than the actual motor windings. If the motor windings are 125°F, what temperature can you expect the motor casing to register?
20° - 30° cooler
When servicing and lubricating a motor, why must the proper oil be used?
To not damage
the bearing, if the grease is too thick it will have a tough time moving.
A direct drive motor is usually connected to a load with a
Coupling
A drip proof motor is designed to prevent any lubricating oil from leaving any of the bearings. T/F
F
The length for a matched set of belts can be +/- 1” of each other and still be usable. T/F
F
The position of the belt in the pulley groove on a drive motor is not a factor in computing motor/blower speed. T/F
F
A motor can burn out if the supply voltage is either too low or too high. T/F
T
When oiling a permanently lubricated motor, a 20-weight, non-detergent motor oil
should be used. T/F
F
Regardless of the type of motor or application, the motor bearings require yearly lubrication. T/F
F
if the drive pulley and the driven pulley are the same size, the drive ratio is
considered to be 2:1. T/F
F
A flexible coupling is used between the motor and prime mover in a direct drive installation. T/F
T
The alignment of a motor and the driven mechanism must be done at room temperature and the motor is at operating temperature. T/F
T
A flexible coupling is used between the motor and prime mover in a direct drive installation. T/F
T
