Soft starter SH11/SH21

The most important advantages:

- Simple wiring
- Quick configuration
- Universally applicable


The universal softstarter from BLEMO®.

A range of units from 0.75 to 15 kW.
With 3 to 85 A rated current for asynchronous motors.
Voltage ranges: 110 to 480 V, 1~ and 3~, power ranges: 0.75 to 15 kW.

Soft starter SH11

The highlights of the SH11/SH21 series


The soft starters of the SH11/21 series provide jerk-free starting (SH11) or starting and stopping (SH21) of asynchronous motors. This avoids torque surges due to the otherwise abrupt starting torque, current peaks during switch-on and voltage dips in the mains and reduces wear on the mechanical drive elements. The SH11 series soft starters for progressive start-up are used with single-phase and three-phase motors when jerk-free starting is desired.

The SH21 series of soft starters for progressive run-up and run-down are used to control the starting torque, to reduce the starting current and for controlled run-down in single-phase and three-phase motors. The soft starters are designed for a voltage range of 110 to 480 V and can therefore be used universally.

Standard features

  • Operating status display with 2 LEDs
  • Booste entrance at SH21
  • Logic output for “Run-up” signalling
  • No neutral conductor (Mp/N) required
  • Simple installation, even retrofitted
  • Jerk-free start-up and shut-down of all machines
  • Available for networks from 110 to 480 V
  • Suitable for all winding circuits
  • Suitable for V3 circuit
  • Top-hat rail mounting
  • Control voltage only required for SH11

Functional principle

In contrast to electromechanical starters, the electronic starters of the SH11/SH21 series allow the adjustment of the starting torque and the starting time. The soft starters are particularly suitable for conveyors and conveyor belts, automatic doors, drag lifts, small gantry cranes, fans, pumps, refrigeration compressors, compressors and machines with high inertia and all machines with belt drive.

Functional description
In the case of the SH11 series soft starters, the current in one phase, and in the case of SH21 in two phases, is controlled as a function of time by a rising voltage ramp.
The starting torque can be adjusted via a potentiometer.
A second potentiometer is used to adjust the ramp-up time according to the requirements.
With the SH21 devices, the deceleration time can be adjusted via a third potentiometer. SH21 units also have a relay output that indicates the status of the softstarter.
After start-up, a built-in bypass relay bypasses the electronics and the motor runs directly on the mains.

your benefits