UNIT 37 REVIEW QUESTIONS ANSWER KEY GO BACK TO INDEX
37-1) Name the two standards organizations that publish standards for electric
motors.
37-2) List the important motor electrical data you need to know when replacing
an electric motor.
Important motor electrical data includes the following:
37-3) List the important motor mechanical data you need to know when replacing
an electric motor.
Important motor mechanical data include the following:
37-4) What is the service factor of an electric motor?
37-5) What motor rotation is indicated by CCWOE?
37-6) What is the distance from the center of the shaft to the bottom of the
mounting base of an IEC 112 frame motor?
37-7) Describe the difference between the three types of starting relays: current
relays, solid-state relays, and potential relays.
37-8) Why do motors mounted on resilient rubber mounts require a ground wire
from the motor to the frame?
37-9) List the three types of motor drives.
37-10) According to Table 37-1, what is the upper and lower limit of a motor with
the voltage of 208/240 V?
37-11) What are the two winding types used for dual-voltage three phase motors?
37-12) Calculate the fan speed for a belt-drive blower which has a 6 inch diameter
37-13) List three general areas of motor problems.
Three general areas of motor failures are as follows:
37-14) What is the difference between a shorted motor and a shunted motor?
37-15) What is the purpose of a megger test on an electric motor?
37-16) What is the first thing to do while testing any motor?
37-17) List four types of electric motor winding failure.
Motor winding failures include the following:
37-18) How do you check the windings of an ECM motor?
37-19) How can you determine if a problem with an ECM motor is in the motor
or the circuit to the motor?
37-20) Describe how to determine the common, start, and run terminals on a
single-phase compressor
A single-phase compressor motor has three terminals: common, start, and run.
37-21) What is the most likely cause for a compressor to have 3.5 ohms of
resistance between the run and start terminals, but infinite resistance (OL) from
the common terminal to either the run or start terminals?
37-22) What is terminal venting?
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37-23) What units are used to specify the output of an electric motor?
37-24) How can a shaded pole motor rated at 10 watts have an amp draw of 0.3
amps on 120 volts ac?
37-25) Arrange these three single-phase motors from lowest to highest efficiency:
37-26) Why are fan motors used on vertical mounts specifically manufactured for
that purpose?
37-27) Draw a connection diagram for a single-speed, three-wire PSC fan motor.
37-28) Draw a connection diagram for a single-speed, four-wire PSC fan motor.
Line Voltage
LINE VOLTAGE
37-29) What do you do with the unused speed wires of a multispeed motor?
37-30) Why should you turn power off to the entire unit before removing any of
the connectors on an ECM motor?
37-31) How can you often spot a bad module on an ECM motor?
37-32) What amount of belt deflection is typical when checking belt tension?
37-33) What size is a 3L-440 belt?
37-34) Describe the characteristics of a worn-out belt.
Worn belts will have one or more of the following characteristics:
37-35) Describe the characteristics of a worn-out pulley.
37-36) Describe how to change the rotation of a PSC service replacement motor.
37-37) Describe how to change the rotation of a three-phase motor.
Swapping any two power leads on a three-phase motor reverses the direction
37-38) Discuss the ratings you need to pay attention to when replacing start and
run capacitors.
When replacing a capacitor, make sure the replacement capacitor voltage
37-39) What is the purpose of a multivalue capacitor?
37-40) What is a hard-start kit and what is its purpose?