Series Reactance Reduced Voltage

In this method, a voltage-dropping reactance is placed in series with the motor during starting. The impedance seen by the power system then is that of the reactance plus that of the motor.

START: R OPEN, S CLOSED
RUN: R CLOSED, S OPEN
CLOSED TRANSITION (R CLOSES BEFORE S OPENS)

 

 

Series Reactor Reduced Voltage Starting

Starting Characteristics:

  1. Motor terminal voltage is reduced from line voltage.
  2. Motor current equals line current.
  3. Starting torque is reduced by the square of the terminal voltage.

Applications:

  1. Usually on high voltage and large low-voltage motors.
  2. Where current reduction requirements are low, or where load torque during acceleration is minimal.
  3. May be used for full acceleration or for system voltage recovery.