Unit 34: Single - Phase Motors

What are the two types of repulsion - start induction - run motors?

1. the brush riding type 2. the brush lifting type

There are three basic repulsion - type motors:

1. the repulsion motor 2. the repulsion - start induction - run motor 3. the repulsion - induction motor

What speed does the Holtz motor operate at?

1200RPM

True or false: All single phase motors operate on the principle of a rotating magnetic field.

False

Does a capacitor start capacitor run motor have a centrifugal switch?

NO

____ motors are fractional horsepower motors and used for low torque applications such as fans or blowers

Shaded pole induction motors

Motors that cant use centrifugal switches use _____. There are three different type which are ___

Starting relays 1. Hot - wire relay 2. Current relay 3. Solid state starting relay

What is the difference in the capacitor start capacitor run compared to the other split phase motors.?

The capacitor start capacitor runs start winding is always energized because a capacitor is in series with the start winding providing a continuous leading current

______ motors are designed to operate with the rotor stalled without overheating

Torque

The _____ motor has a high starting torque

capacitor start induction run

Motors that are hermetically sealed cannot use a _____ to disconnect the start winding.

centrifugal switch

What type of winding does a universal motor have that helps overcome inductive loads?

compensating winding

The capacitor - start capacitor - run motor helps ____

correct power factor

Shaded - pole motors are considered ____

nonreversible

What are AC servo motors used for?

position control

What are stepping motors generally used for?

position control

Split phase motors start as two phase motors by _____ condition for the current in the run and start winding

producing an out of phase

Shaded pole induction motors operate on the principle of a _____

rotating magnetic field

The rotating magnetic field of a shaded - pole induction motor is produced by placing ______ on one side of the pole piece

shading loops or coils

Consequent - pole motors are used when a change of motor ____ is desired and high ____ must be maintained

speed / torque

The direction of rotation for split - phase motors is changed by reversing the ___ winding in relation to the ____ winding

start / run

Multispeed fan motors have high - impedance ____ windings to prevent them from ____ when their speed is reduced

stator / overheating

Dual voltage split phase motors use ___ and ___ windings

two start windings and two run windings

The capacitor - start capacitor - run motor operates like a _____ because both the start and run windings _____ during motor operation

two-phase motor / remain energized

What determines the synchronous speed of a single phase motor and a three phase motor?

1. Number of stator poles per phase 2. Frequency of the applied voltage

What are the three types of split phase motors?

1. The resistance start induction run 2. The capacitor start induction run 3. The capacitor start capacitor run

AC servo motors contain an encoder that ____

1. determines speed 2. number of shaft rotations 3. direction of rotation

What is another name for a universal motor?

AC series motor

Universal motors can operate on ____

DC or AC

In an resistance - start induction - run motor, the ______ of the wire is used to produce a phase angle difference between the current in the start winding and the run winding

resistance

____ motors have low starting and running torque

shaded pole induction

The synchronous - filed speed of a single - phase motor is determined by the number of ____ and the _____ of the applied voltage

stator poles / frequency

What type of motor can a stepping motor be used as when connected to AC?

synchronous

What are the two types of single phase synchronous motors?

the Warren and the Holtz

The repulsion - induction motor contains both a ____ and ____

wound armature / squirrel cage windings

What factors determine the amount of starting torque produced by a split phase motor?

1. The strength of the magnetic field of the stator 2. The strength of the magnetic field of the rotor 3. The phase angle difference between current in the start and run winding

The direction of rotation of repulsion motors is changed by setting the brushes ___ on either side of the ___ winding

15 degrees / run

What speed does the Warren motor operate at?

3600RPM

Stepping motors operate at a speed of ____ when connected to 60 hertz AC

72 RPM

Max starting torque for a split phase motor is developed when the start and run current are _____ with each other

90 degrees out of phase

The capacitor - start induction - run motor uses an _____ to increase the phase angle difference between starting and running current. This causes an _____ in starting torque

AC electrolytic capacitor / increase

Most capacitor - start capacitor - run motors use an _____ connected in ___ with the start winding

AC oil-filled capacitor / series

Stepping motors generally operate in ___ and are used to produce ____

DC / angular movements in steps

What type of armature does a Universal motor have?

wound armature with brushes

What does a brush RIDING type of motor use once it reaches 75% of full load?

an AXIAL commutator and a short - circuiting device, which short circuits the commutator segments at 75% speed

What does a brush LIFTING type of repulsion - start induction - run motor use at 75% of full load?

an RADIAL commutator which is a CENTRIFUGAL device that causes the brushes to move away from the commutator and a short circuiting necklace to short circuit the commutator

How can you change the direction of rotation for a universal motor?

by changing the armature leads with respect to the field leads

Most resistance - start induction - run and capacitor - start induction - run motors use an centrifugal switch to ___ the start windings when the motor reaches ___ of full load speed

disconnect / 75%

Repulsion motors have the ____ starting torque out of all single phase motors

highest

Stepping motors can produce a ____ when DC is connected to their windings

holding torque

What are single phase synchronous motors sometimes called?

hysteresis motors

Multispeed fan motors are constructed by connecting windings in ____ with the main ____

series / run winding