Ch 34 Single-Phase AC Motor

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In a potential start relay how is the start relay coil connected to the start coil

they are connected in parallel

What factors determine the starting torque of a split phase motor

The strength of the magnetic field in the stator. Strength of the magnetic field in the rotor. The phase angle between the start windings and the Run windings

What is the name of the electronic component used in a solid state relay

Thermistor

what principle does the split phase Motors operate on

a rotating magnetic field

what would be some examples of why you would need a synchronous motor

clocks, timers and recording instruments

What are the two types of multi-speed motors

consequent Pole. Capacitor start capacitor run

Most split phase induction motors have run windings with a resistance of 1 to 4 ohms. however the multi Speed Motor has run windings of what resistance

10 to 15 ohms

what is the speed of a Holtz motor

1200 RPM

Multi speed motors

1625. 1500. 1350. RPMs

what is the speed of a Warren motor

3600 RPM

What happens to the Armature windings in a repulsion type motor once a magnetic field is induced into the pole pieces of the stator

Current begins to flow through the Armature windings

on what principle does the solid state relay work

Heat

Describe the characteristics of a synchronous motor

RMF RPM equals RPM of shaft

What are the three types of split phase Motors

Resistance start induction run. Capacitor start induction run. Capacitor start capacitor run

What are two types of single-phase synchronous Motors

Warren and Holtz

What are the two types of repulsion start induction run motor

brush riding. bush lifting

How can the speed of a repulsion motor be varied

by changing the ac voltage Supply

How do you change the direction on a split phase motor

by changing the leads of the start winding

what should you not do to protect a capacitor start induction run motor

do not start this motor more than eight times in one hour

If a dual voltage split phase motor only has one start winding how could the leads be labeled

either T5 T6 or T5 T8

What type of loads do multi-speed Motors typically run

fans and blowers

How are the Run windings and start windings in a split phase motor connected

in parallel

does a repulsion type motor have a start winding

no repulsion type Motors only use a run winding

Capacitor in a capacitor start capacitor run split phase motor is usually what

oil filled

what is the operating principle of a synchronous motor

operates on a rotating magnetic field using shade poles in the stator

characteristics of a repulsion induction motor

same as a repulsion motor except a squirrel cage rotor is added to the Armature

What type of rotor does a split phase motor have

squirrel cage

a shaded pole induction motor uses what kind of rotor

squirrel cage

How Is a shaded pole induction motor different from a split phase induction motor

the Shaded pole induction motor as no start winding

what is slip

the rotating magnetic field RPM minus the shaft RPM equals the slip

What two windings are used to create the split phase in a single phase motor

the start winding the Run winding

Describe how the potential start relay works

when power is applied to the circuit the potential start relay closes and Power is being supplied to the start relay. Once the motor reaches 75% of full speed the start relay opens and the start "relay" coil becomes De-energized. The start winding continues to receive power from the Run capacitor

What creates the rotating magnetic field in a split phase motor

when the current flow in the Run windings are out of phase with the start windings

In a resistive-start Induction-run split phase motor what is a typical phase angle

35 to 40%

repulsion type Motors contain the same number of brushes and stator poles. what are the most common number of stator poles in a repulsion motor

4, 6 or 8

What is the ideal phase angle for maximum torque in a split phase motor

90 degrees out of phase

If not hermetically sealed what type of start capacitor would be added to a capacitor start capacitor run split phase motor

A Centrifugal Switch

What are the two ways to connect the compensating windings in the Universal motor

Conductive (Series). Inductive (Shortened Together)

3 types of relays used in a hermetically sealed split phase motor

Hot wire Relay. Current relay. Solid state relay

If a dual voltage split phase motor has to start windings how would they be labeled

T5 T6 T7 T8

Compare a phase angle with power factor

a phase angle of 90 degrees would equal a power factor of 1

How does a repulsion start induction run motor start and run

a repulsion start induction run motor starts like a repulsion motor and runs like a squirrel cage motor

On what principle does a hot wire relay function

a resistance wire heats up. First causing the contacts to close on the start winding. If the resistance of the wire continues to heat an overload relay will open to stop the motor from being damaged

In the brush riding repulsion start induction motor what type of commutator is used

axial commutator

Why are Shaded-Pole induction Motors popular

because of their Simplicity and long life

where would the main run winding be in a multi-speed motor

between the common and the high-speed connection

how would you reverse the direction and a repulsion type motor

if the brushes are set at an angle of 15 degrees in front of the stator Pole the motor will operate in a clockwise Direction. If the brushes are placed at a 15 degree angle behind the poles of the stator the motor will operate in a counterclockwise Direction

What is a repulsion type motor's Rotor called

it is called an Armature because it has a slotted metal core with winding through the slots

What is the operating principle of the Shaded pole induction motor

just like split phase Motors the principle of the Shaded pole induction motor is a rotating magnetic field

Describe run windings in a split phase motor

larger wire placed near the bottom of the stator

what are common values for slipped

less than 2%. 2 to 5%. Greater than 5%

What would happen if there was no mechanical load connected to the shaft of a repulsion motor

motor race at a very high speed

When AC reaches Peak voltage what is the induced voltage of a shaded coil

no

How could you increase the starting torque of a capacitor start capacitor run split phase motor

place a second capacitor in series with the start windings

If a capacitor start capacitor run motor must be hermetically sealed what type of additional start relay would be used

potential start relay

What is the operating principle of a potential start relay

potential start relay senses voltage in the start winding

Describe the relationship between the stator fields and the rotor fields in a split phase motor

power comes into stator windings and induces a rotating magnetic field in the rotor bars. The induced voltage is in phase in the stator windings. And the current in the rotor is 90 degrees out of phase with the stator

What is the operating principle of a repulsion type motor

repulsion type Motors operate on the principle of like poles repel.

How would you change the direction of a dual voltage split phase motor

reverse the start windings

how would the Run windings be connected in a dual voltage split phase motor if operating on low voltage

run windings would be connected in parallel

How are the brushes of the repulsion type motor different from the brushes of a DC motor

the brushes are shorted together. the brushes function to provide a current path through the Armature.

What advantage does a capacitor start induction run split phase motor have over a resistant start induction run motor

the capacitor start has a much greater starting torque

And a brush writing repulsion start induction run motor what happens to the motor when 75% of full speed boat is reached

the copper segment swings out and makes contact with the commutator. the motor then operates like a squirrel cage motor

Describe the current flow through the in a split phase motor

the current flow through the Run winding LAGS the applied voltage do to inductive reactance

What determines the direction of rotation of a split phase motor

the direction is determined by the rotation of the magnetic field

In a shaded pole induction motor what happened to the magnetic lines of flux when voltage is induced

the magnetic lines of flux begin to increase

What happens to the speed of a multi -speed motor when load is added

the motor slows down

which type of motor has the highest starting torque of any single phase motor

the repulsion type motor

When ac voltage starts to decrease what happens to the magnetic lines of flux in the Shad coil

the shade coil creates a current that opposes the magnetic flux

how is a capacitor start capacitor run split phase motor different from the induction run Motors

the start winding remains energized at all times

In a dual-voltage split phase motor how are the Run windings and the start windings connected

the start windings are always connected in parallel to the Run windings

why does the Armature in a repulsion motor rotate

the two magnetic fields of the stator and the Armature oppose each other

when you split the current flow in a split phase motor what happens to the voltage

the voltage becomes 90 degrees out of phase

What are advantages of a solid state relay

they are more reliable and less expensive

how would you connect the Run windings on a high voltage split phase motor

they would be connected in series

the capacitor is connected in series with the start winding for what reason

to provide continuous leading current

describe what happens when a brush lifting repulsion start induction run motor reaches 75% of the full operating speed

weights are mounted to the front of the Armature period at 75% of Speed The weights swing out and cause the brushes to no longer be in contact with the commutator. this will create a longer life and a quieter motor

What happens when you place a capacitor in series with the start windings in a split phase motor

you can get a phase angle of 90 degrees. this will create the highest starting torque possible

How do you split the phase on a single phase motor

you have to split the current flow through two separate windings

Why is a shaded coil induction motor considered to be non-reversible

you would have to change the whole pieces in the stator

What is the power factor of a capacity start capacitor run motor

.98 - .99 ( A perfect PF would equal 1)

The brushes that ride on the commutator of a repulsion type motor will affect the torque . what angle creates the highest amount of torque in a repulsion motor

15 degrees before or 15 degrees after the stator Pole

What principle does the current relay function

A magnetic field that is controlled by current flow through a coil connected in series with the Run winding. When the thermostat closes, current begins to flow through this coil, which becomes magnetized, and closes the contact on the start winding. This reduces the current flow in the Run winding and the magnetic field decreases and the start winding contact open

In a dual-voltage split phase motor how are the Run windings labeled

T1 T2 T3 T4

What two factors determine the speed of a split phase motor

The number of stator poles. The frequency of the applied voltage

Multi speed motors have what kind of running torque

a high running torque is maintained at different speeds

what happens when AC power is induced into the stator windings of a repulsion type motor

a magnetic field in the poles of the stator is created that has alternating polarities

What determines the speed of a shaded pole induction motor

frequency of the induced voltage. Number of stator poles ( usually 4 to 6)

When the rotary switch and a multi-speed motor is adjusted from medium to low

inductance is in the Run windings causing a decrease in the current flow causing a decrease in torque causing a decrease in speed

What happened when you switch from the high speed setting to the Medium Control winding in a multi Speed Motor

inductive reactance increases which causes limited current flow. this decreases the magnetic field which causes less torque. Speed of the motor decreases. this is the amount of slip

what is the operating principle of a repulsion type motor

it is and induction motor. it does not operate on the principle of a rotating magnetic field

what type of commutator does a brush lifting repulsion start induction run motor used

radial commutator

What is an advantage of a repulsion induction motor over the repulsion motor

repulsion induction motors have the same high starting torque but a better speed control. very good speed control between no load and full load

Name three basic types of repulsion type Motors

repulsion motor. Repulsion start induction run. Repulsion induction motor

Describe the properties of start torque and run torque of a shaded coil induction motor

start torque and low running torque

What do the brushes of a repulsion type motor make contact with

the brushes make contact with the surface of the commutator bars

what is the advantage of a capacitor start capacitor run split phase motor

they have hi starting and running toward and run quietly and with high efficiency

How are the Run windings of a multi-speed motor connected

they are connected in series and use inductance to control speed

What are the windings in the Armature of a repulsion type motor connected to

they are connected to the commutator bars

What characteristics describe a start winding in a split phase motor

they are small wires placed near the top of the stator


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