Assignment 3
List five methods used in split-phase motors to disconnect the start winding.
1. Centrifugal Switch
2. Hot-Wire Relay
3. Current Relay
4. Potential Relay
5. Solid-State Starting Relay (Thermistor)
What components does a capacitor-start induction-run split phase motor have in the start
winding circuit?
Electrolytic capacitor and a centrifugal switch
In a resistance-start induction-run split-phase induction motor, run field windings are wound with ________ turns of ________ gauge wire relative to the start field windings
Fewer, larger
To reverse a 6-lead split-phase induction motor, which wiring connections are
interchanged?
T5 – T8
Is the starting torque characteristics of a capacitor-start motor greater than or less than the
starting torque characteristics of a resistance-start motor?
Greater
Which type of disconnecting means for split-phase motors functions as both a starting
relay and an overload relay?
Hot-Wire Relay
Which split-phase induction motors have their start winding disconnected after initial
rotation is developed during start-up?
Resistive Start induction run and Capacitor Start induction run
Which split-phase motors have their start winding energized at all times?
Capacitor Start – Capacitor Run motor and the Permanent Split induction run
What is the maximum phase displacement angle between the start and run windings of a
capacitor-start induction-run split-phase motor?
Up to 90°
What is the function of a centrifugal switch?
Disconnect Start winding (Resistive Start induction run)
Disconnect Start winding and Start Capacitor (Capacitor Start induction run)
Disconnect Start Capacitor (Capacitor Start Capacitor Run)
What type of single-phase motor would be best suited to be used for a residential
refrigerator?
Capacitor Start Induction run
What is a thermistor?
Solid-State Starting Relay
Is the resistance of a start field winding higher or lower than the resistance of the run
field winding in a capacitor-start induction-run split-phase induction motor?
Higher Resistance
What are the minimum number of stator leads required for a single-voltage, reversible
split-phase induction motor?
4 - Lead
What are the minimum number of stator leads required for a dual-voltage, reversible
split-phase induction motor?
6 - Lead
What are the minimum number of stator leads required for a single-voltage, non-
reversible split-phase induction motor?
2 - Lead
List three applications of permanent-split capacitor motors.
1. Central air conditioning, Air handlers
2. Blowers, Fans
3. Commercial Refrigeration
List three applications of resistance-start induction-run motors.
1. Washing Machines, Dishwashers
2. Clothes dryers, Unit Heaters
3. Reversible Fans
List three applications of capacitor-start induction-run motors.
1. Refrigerators, freezers, Compressors
2. Pumps, Furnaces, Fans
3. Heavy starting loads
List two types of capacitors used in split-phase induction motors.
1. Electrolytic type Capacitor
2. Oil-Filled type Capacitors
Calculate the rotor speed of a 4 HP, 230V, 1∅, eight pole, continuous duty split-phase induction motor operating at 4% slip with 80% power factor and 78% efficiency connected to a 60 hertz source.
Syn speed = 120 x F / # of poles
Syn speed = 120 X 60 Hz / 8 poles
Syn speed = 900 rpm
Slip Speed = Syn Speed X %Slip
Slip Speed = 900 rpm X .04
Slip Speed = 36 rpm
Rotor Speed = Syn Speed – Slip Speed
Rotor speed = 900 RPM – 36 RPM
Rotor Speed = 864 RPM
Capacitor-start induction-run split-phase motor components
1. Terminal Box
2. Base
3. Frame
4. Ball Bearing
5. End Plate
6. Cooling Fan
7. Squirrel Cage Rotor Assembly
8. Stator Field Windings
9. Electrolytic Capacitor
10. Cooling Fan
11. End Plate
12. Stationary Switch