Industrial power resistors, dynamic braking, load banks, low resistance grounding, high resistance, grounding, harmonic filters, motor controls, resistor element types

Other Motor Control Resistors:

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

3 Step / 4 Speed Diagram


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)

1 Step / 2 Speed Diagram

 

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)

Wound Rotor Motor Resistor - Resistance Calculation


More Information:

WOUND ROTOR MOTOR RESISTORS TECH SHEET MC105-07

 

Wye-Delta Closed-Transition Starting Resistor

Wye-delta is a reduced-inrush starting method in which 3 phase motor stator coils are initially connected in a wye configuration and switched to delta as the motor's speed increases. The resistor works as a reduced voltage starting resistor by starting a motor at 58% reduced voltage.

Initial information needed for sizing your resistor:

  • Application
  • Horsepower
  • Line voltage
  • Full load amps
  • Duty/NEMA class (see tables)

For other applications, such as small horsepower motors, dynamic braking, and field discharge, please give us a call. We offer free engineering assistance to our customers for all motor control applications

 

 

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