EM Series:

EM series motor protection On/Off switches can be supplied in 10 settings ranges from 0.3 to 16 amps. In addition to thermal triggering, the switch can also be supplied with quick kA magnetic triggering or UA low-voltage triggering.

Operation by means of insulated T-handle is via a robust switching latch with rotary drive. In the version with low-voltage triggering. EM switches ensure the protection called for in the DIN EN 60204 Part 1 provisions against automatic restarting when power is restored following a power cut. The nominal frequency is 50 Hz. Switches for other voltages with a frequency of 50 or 60 Hz can also be supplied on request.

MN Series:

The MN series motor protection switches are cam switches with thermal over-current trip devices integrated within the switch. The base unit forms the contact chamber with the cam wheel for function control. In the event of excess current, the bi-metals cause the switching latch to be operated via a trip shaft. This interaction enables a multitude of switching programs with integrated motor protection to be produced.

Due to the switching of the bi-metals within the current circuit there are 2 different series in terms of the setting ranges: for On/Off switches, reversing switches, pole-changing switches (1 rotary speed protected) and single-phase starter switches 12 setting ranges of 0.3 to 21.5 amps have been defined.

The star-delta switches are sub-divided into 7 setting ranges of 2.85 to 37 amps, with the bi-metals wired up in such a way that they are in the motor’s phase current circuit. The motor coil is thus protected both in the star and the delta position.

The current to be set on the setting scale is the motor’s rated current. Star-delta switches for extremely difficult starting up are used where – due to the drive system – a long start-up period in the star position is required. So that the motor protection is not triggered during the start-up phase, the bi-metals are placed such that only in the delta position are they connected up in the current circuit. With this form of switching the motor is thus protected only in the delta position.

The machine and device protection switch have been developed for use with standard machines up to a power output level of 4kW in AC-3 at 400V. The combination options of thermal and/or low-voltage triggering enables the appropriate selection of protection function to be offered in connection with the different designs. Even if the handle is jammed, the switch trips via a robust switching latch and prevents any starting up again.


Many of our switches are available in enclosed form and suited to direct switching of motors. They have AC-3 breaking capacities as per EN 60947-3. In addition to the standard units, there are special switches, versions with a fuse block / locking mechanism or with a CEE plug and low-voltage circuit breaker.

  • Motor switches
  • Toggle switches for emergency power feeds
  • Repair switches
  • Special switches

Motor Switches with CEE plug and MCB:

Taken into the account in the design of these devices are the VDE provisions of DIN EN 60204 Part 1, section 7.5 (protection against automatic restarting when power is restored following a power cut)