CDC 3E051A Vol.3 Unit 5

Which of these items is not a part of a direct current (DC) motor ?

A) Endbells.
B) Brush assembly.
C) Armature.
D) Stator.

The direct current (DC) shunt motor connects the field coils and armature in

A) Parallel.
B) Series-parallel.
C) Parallel-series.
D) Series.

The component of a three-phase motor connected to the load is the

A) Endbell.
B) Rotor.
C) Stator.
D) Armature.

The magnetic field of a three-phase motor rotor is caused by

A) Resistance in the squirrel cage.
B) Current flow in the rotor.
C) Voltage in the end bells.
D) Impedance of the stator.

Which of the following features describes three-phase motor best ?

A) Always single-voltage motor.
B) Always dual-voltage motors.
C) Must be supplied by 220 volts.
D) Either single-or dual-voltage motor.

The motor that requires some starting means is the

A) Universal motor.
B) Direct current (DC) shunt motor.
C) Three-phase alternating current (AC) motor.
D) Single-phase AC motor.

A single-phase motor with external leads numbered T1, T2, T3, T4 is what type ?

A) Dual-voltage reversible.
B) Dual-voltage nonreversible.
C) Single-voltage nonreversible.
D) Single-voltage reversible.

Normally, an across-the-line motor control incorporates some type of

A) Motor speed control.
B) Motor over-current protection.
C) Lightning protection.
D) Frequency control.

The basic types of overload relays are

A) Undervoltage and overcurrent.
B) Mechanical and magnetic.
C) Single-and three-phase.
D) Thermal and magnetic.

The methods used to open the contacts on an across-the-line magnetic controller are

A) Spring tension and gravity.
B) Magnetic and thermal.
C) Metallic and magnetic.
D) Thermal and hydraulic.

A temperature-sensitive device to operate a magnetic across-the-line starter automatically is a

A) Float switch.
B) Thermostat.
C) Photoelectric cell.
D) Pressure switch.

What are the three sections of a variable frequency drive ?

A) Pulse width modulation (PWM) Converter, DC Bus, and Inverter.
B) Converter, Rectifier, and Inverter.
C) Converter, direct current (DC) Bus, and Inverter.
D) Converter, alternating current (AC) Bus, and Inverter.

What type of bearing should be used in a vertically-mounted motor ?

A) Oillite sleeve.
B) Phenolic and brass sleeve.
C) Bronze sleeve.
D) Ball or roller.

When you clean a motor with compressed air, what is the maximum air pressure to use ?

A) 15 pounds per square inch (psi)
B) 50 psi.
C) 35 psi.
D) 30 psi.

If a motor has been operating normally but suddenly stops, you should suspect

A) Overvoltage.
B) Electrical overload.
C) Worn brushes.
D) Improper connections.

The end play of a motor should not exceed

A) 1/8 of an inch.
B) 1/64 of an inch.
C) 1/16 of an inch.
D) 1/32 of an inch.

The conductor common to both the starting and holding circuits is connected to terminal

A) L1.
B) T1.
C) T2.
D) L2.

A motor that operates slowly may have a

A) Blow fuse.
B) Ventilation problem.
C) Deficient voltage supply.
D) Bad conductor.

Which of the following motors has the highest horsepower-to-weight ratio?

A) Single-phase capacitor start motor.
B) Three-phase dual-voltage motor.
C) Universal motor.
D) Direct current shunt motor.