A motor starting reactor is a reduced voltage starting method that reduces terminal voltage of an induction motor
  when starting it.

 This method is to drive a motor with direct line by short-circuiting a reactor when complete starting
  is made (after t seconds) with terminal voltage rising as current is reduced while a motor starts from complete stop.
  This facilitates starting a motor by limiting starting current and prevents accidents by other power equipments such as
  error of instruments.