Deck 7: Motor-Circuit Wiring

Question 1

A(n)____________________ is a device to convert electrical energy into mechanical energy or power.

Answer 1

electric motor

Question 2

How did the factor used in the determination of conductor size change with the 2011 changes to the Code?

Answer 2

In the case of a wye-start, delta-run motor, the previous edition of the Code did not include a factor of 1.25 in the determination of the conductor size for the conductors between the controller and the motor.In the past, the instruction was to use 0.58 times the motor full-load current.

Question 3

How does one start a 3-phase,delta connected motor that has all six leads available?

Answer 3

A 3-phase, delta connected motor that has all six leads available can be reduced-voltage started by connecting the windings in a wye configuration during starting, then switching the windings to a delta configuration when the motor reaches nearly full speed.

Question 4

Why is condensation inside a motor problematic?

Question 5

What is a phase converter?

Question 6

The motor will typically draw a maximum of _____________________ times as much current during starting as it will when running under constant full load.

Question 7

Name two common types of control circuit wiring for a magnetic motor starter.

Question 8

A motor with a temperature rise of ____________________ F or less is designed to run relatively cool; therefore, it has greater overload capacity.

Question 9

____________________ are sometimes installed inside motors to keep the inside warm enough to prevent condensation when not in operation.

Question 10

What is a rectifier bridge?

Question 11

A disconnecting means is required to be located within sight of the ____________________.

Question 12

A totally enclosed motor frame is guaranteed to keep out moisture.

Question 13

The rotor of an induction motor will always turn at a speed slightly faster than the stator magnetic field.

Question 14

A single set of fuses will serve as both branch-circuit short-circuit and ground-fault protection, as well as overload protection for the motor.

Question 15

Most static phase converters consist primarily of capacitors.

Question 16

The ____________________ temperature is the maximum environmental temperature in which the motor is to be operated.

Question 17

Rotary phase converters are capable of supplying one or more loads.

Question 18

What do the 2011 changes in CODE say about circuit protection?

Question 19

The majority of the electric motors in use are ____________________ that operate at a nearly constant speed.

Question 20

If the frequency of the supply to the motor can be increased, the rotor will turn at a(n) ____________________ (slower/faster) speed.