Motor brake relays

Motor brake relays are used with view to safety and efficiency. With braking currents up to 600 A DOLD braking units allow a reliable deceleration of asynchronous motors up to 160 kW. They can be used to bring your machines to a standstill within 10 s as required by the European Directive on Machinery.

  • Easy installation, also in existing plants
  • Free from wear and maintenance
  • Adjustable braking currents allow optimal tailoring to machines and plants
  • Automatic zero-speed monitoring ensures precisely accurate braking current cutoff and spares time-consuming readjustments
  • Thermistor motor protection prevents inacceptable motor heating

What is DC Injection Braking?

DC Injection braking is an effective electrical method of stopping a rotating AC asynchronous motor.

How does it work ?

An AC electrical motor works on the basic principle of opposing magnetic poles attracting each other. If you create a rotating magnetic field in the stationary (stator) windings of a motor, a magnetic field of the opposite polarity in the rotating (rotor) windings will naturally want to follow it trying to align itself (Fig.1).

If you were to then create a stationary magnetic field in the stator, the attracted opposing fields in the still rotating rotor windings will try to align themselves with the stationary field, creating a strong braking force. This is what happens when a DC current is Injected into the ‘Stator’ windings of a motor.


  • Wood working machines
  • Centrifuges, belt conveyor drives
  • Textile machines
  • Mills, grinding machines
Motor brake relay MINISTOP
Function Braking current
adjustable up to
[A] max.
Braking time
up to [s] max.
External brake
Motor brake relay 60 30 + + + 90 BI 9034
Motor brake relay 25 11 + 45 BA 9034N
Motor brake relay 80 20 + + 90 BI 9023
Motor brake relay 25 15 + optionally + 100 BN 9034
Motor brake relay 600 320 + optionally from 100 A + 110 GB 9034
Softstart with d.c. brak 60 30 + + 90 BI 9028
* Following product are also available: