Electric Motor Troubleshooting 1

A(n) _____ motor has to work harder than it was designed to work, which can lead to premature failure

• A) Overloaded

• B) Under loaded

• C) Oversized

• D) Locked rotor

DC motors failures can be mechanical or _____ in nature

• A) Physical

• B) Logical

• C) Electrical

• D) Resistive

Reduced brush contact with the commutator causes high armature current, _____, and commutator wear

• A) Filming

• B) Sparking

• C) Contouring

• D) Abrading

The first step to diagnose a DC motor failure is to _____

• A) Measure with a multimeter

• B) Measure with a megaommeter

• C) Observe using four of the five senses

• D) Test run

To test a stopped motor, use a multimeter and _____ to check the resistance of the windings, brushes and insulation

• A) Tachometer

• B) Clamp-on meter

• C) Encoder

• D) Megohmmeter

Two conditions can be observed to determine the health of the commutator: film _____ and surface smoothness

• A) Density

• B) Thickness

• C) Striations

• D) Color

The most common electrical instrument used to test a DC motor is a(n) _____

• a) Multimeter

• b) Clamp-on meter

• c) Megohmmeter

• d) Tachometer

The insulation resistance to ground should be __________ megaohm per kilovolt, with a 1 megaohm minimum for any megger test.

• a) 1

• b) 10

• c) 100

• d) 1000

When using a megger to test insulation, one probe is connected to the winding and the other probe is connected to __________.

• a) The other end of the winding

• b) A different winding

• c) Ground

• d) Neutral

DC motor field windings are subject to __________ in a winding, an open winding, and individual windings shorted to the motor frame or to other windings.

• a) Contraction

• b) Shorts

• c) Heating

• d) Expansion