Resistor Elements
Other Motor Control Resistor Applications
DC Series Wound Motor Resistor
The resistor limits torque by limiting current flow to the motor. It is used for starting and stopping the motor.Initial information needed for sizing your resistor:
- Application
- Horsepower
- Line voltage
- Full load amps
- Starting torque
- Number of speeds
- Duty/NEMA class (see tables)
- For dynamic lowering applications, include manufacturer of control
AC Squirrel Cage Induction Motor Resistor
Commonly known as a “reduced-voltage” or “ballast” resistor, this resistor acts as a voltage divider for soft starting of the motor.Initial information needed for sizing your resistor:
- Application
- Horsepower
- Line voltage
- Full load amps
- Duty cycle/NEMA class (see tables)
AC Wound Rotor Induction Motor Resistor (Slip Ring Motor)
The resistor is wired into the motor secondary slip rings, where it dissipates torque energy in the form of heat. It also provides “soft starting” as resistance is removed in steps.Initial information needed for sizing your resistor:
- Application
- Horsepower
- Secondary volts
- Secondary amps
- Starting torque
- Number of speeds
- Duty/NEMA class (see tables)
