Motors II exam review

Polarity

A DC motor can be reversed by changing this on either the armature winding or the field winding

Split phase motor

A capacitor start motor operates much the same as this motor, centrifugal switch that opens at approximately 60 to 80% of full load speed

Capacitor run motor

A permanent split capacitor motor is also known as this type of motor

"Fused device"

According to 430.52, what type of device is a motor short circuit protector?

0 to 6000 A

Cartridge fuses are available with amperage ratings in a range from...

Three types of wound rotor motor regulators

Drum switch, three pole rheostat, silicon controlled rectifier's

True

Fuses themselves do not need to be maintained. The fuse holders, terminations, and disconnects should be inspected regularly

Small amounts of overcurrent

Generally, motor overload protection only protects against...

Drum

If a capacitor start motor is to be reversed often, then one of these switches or a foot switch can be used to reverse the current through the start with respect to the run windings

Use the next size up

If starting current is a problem, do this...

Split phase motor

One of these motors is a single phase AC motor that includes a run winding and resistive start winding used in applications were starting is easy, such as fans, business machines, machine tools, and centrifugal pumps

On a 3phase wound rotor motor, ——- is the conductor, and ——- ——is the insulator

Pigtail....brush holder

Overcurrent protection

The NEC requires this of all motor installations

Overcurrent

The function of an OCPD is to protect branch circuit conductors, control equipment, and motors from damage caused by this

Commutator

The function of this device is to keep armature windings in the correct polarity to interact with the main fields of a motor

Armature windings

The inner polls are connected in series with these

Single phase motors

These motors do not have a rotating magnetic field and are named for the method used to develop the rotating magnetic field

Time delay fuses

These type of fuses do not allow over current to exist, to avoid Nuisance tripping due to equipment start up characteristics

Short circuit condition

This condition causes the current to rise hundreds of times higher than normal at a very fast rate

Shaded pole

This is a short circuited winding, which consist of a single term of copper wire and ask on only a portion of the stator windings

Overload

This occurrence in the motor is caused by a load that exceeds the full loading rating of the motor

Ground fault

This occurrence is an unintentional connection between an ungrounded conductor and any grounded raceway, box, enclosure, or fitting

DC generator

This operates on the principle the voltage is induced in a coil of wire when the coil is rotated in a magnetic field

Thermal magnetic breaker

This type of circuit breaker uses a buy metal strip connected in series with the load to open circuit

Squirrel Cage

This type of motor has conductor bars in it. Conductor bars are attached to a shorting ring. On a wound rotor motor... The rotor is made from insulated copper windings that are not shorted

Series wound DC motor

This type of motor has the highest starting torque

Thermal overload relay

This type of overload relay uses it was just a heating element to open a set of contacts

Capacitor motor

Typical applications of these motors include fairly hard to start loads, like refrigerators, air conditioners, air compressors and some power tools

Motors, motor control apparatus, and motor branch conductors

What are overload devices intended to protect?

Add Resistance

What do we do to create higher torque in a three phase wound rotor motor?

you have to physically remove the rotor

What do you do if you want to change the direction of a shaded pole motor

You have to flip-flop one of the two windings

What do you do if you want to change the direction of a split phase motor?

Switch the two start leads in the circuit

What do you do to cause the rotor of a single phase motor to turn in reverse?

Reduced by half

When the dual voltage single phase motor is reconnected for the higher voltage (115 to 230 V), current is reduced by?

We're OCP power loss would cause a greater Hazzard... Like fire pumps

Where are the provisions for overload protection not required?

Locked in place

With rotation is not possible because of the stators field and the rotors field or equal or parallel to one another, the rotor is this...

6 times

for small motors not covered by the NEC, locked rotor current shall be assumed to be this many times the FLC

line to ground fault

what condition is not protected by motor overloads