1. Chapter 3
Manual Starters

2. Objectives Discuss the operation of manual motor starters
Discuss low voltage release
Connect a manual motor starter
Check a circuit to determine if a motor is drawing excessive current

3. Introduction Manual starters:
Operator must go to the starter to initiate any change
Some look like a toggle switch with an overload heater
Others are operated by push buttons and may be capable of low voltage protection

4. Fraction Horsepower Single-Phase Starters
Toggle switch lever mounted on front
Used to control the on/off operation
Provides overload protection
Overload heater connected in series with the motor
When current flows, the heater produces heat in proportion to the motor current

5. Fraction Horsepower Single-Phase Starters (cont’d.)
Starters intended to protect motors operating on 240 volts should contain two load contacts
Are intended to control fractional horsepower motors only
Do not provide low voltage release
Do not contain an electrical coil

7. Fraction Horsepower Single-Phase Starters (cont’d.)
Mounting requires little space:
Can be mounted in a single gang switch, conduit box, or directly onto a piece of machinery
Open type can be mounted in the wall and covered with a single gang switch cover plate
Available in different enclosures

9. Fraction Horsepower Single-Phase Starters (cont’d.)
Automatic operation
Sometimes combining the manual starter with other sensing devices is necessary
Pilot device must be equipped with contacts that can handle the rated current
“Line voltage” devices have larger contacts

12. Manual Push-Button Starters
Integral horsepower starters
Two-contact models are intended to control single-phase motors operating on 240 volts, or direct current motors
Three contacts are intended to control three-phase motors

13. Manual Push-Button Starters (cont’d.)
If any overloads trips, a mechanical mechanism will open the load contacts and disconnect the motor from the line
After cooling, it must then be reset by pushing the STOP button

15. Manual Push-Button Starters (cont’d.)
Low-voltage release and low-voltage protection
Both employ a solenoid that senses voltage
A voltage drop disconnects power
Low-voltage release automatically restarts when power is restored; low-voltage protection must be manually reset

17. Troubleshooting Determine whether the motor is actually overloaded
Bad bearings, shorted windings
Simplest way to determine overload
Find the motor full load current on the nameplate and then check the running current with an ammeter

19. Troubleshooting (cont’d.)
Thermal overloads:
Loose connections
Ambient, or surrounding, air temperature
Set a fan that blows on the starter to help remove excess heat
Vented cover plates