Why Solid State solutions for three-phase AC motor control ?

Motor control has always been something difficult to tackle with as a motor is first of all an inductive type of load with high starting currents (which doesn’t help reduce size and costs of protection devices like fuses) and over voltages generated at turn-off.

This is why Solid State solutions are more and more popular to control motor loads. Another big advantage of using power electronics is that numerous control modes can easily be performed thanks to very fast response time, and computing power of micro-processors.


celduc® relais specialising in Solid State Relays manufactures in France with a high level of quality a complete range of Solid State Contactors for motors, as well as soft starters and motor reversers.

Three-phase ON/OFF Solid State Relays

celduc relais offers a wide range of ON/OFF three-phase zero cross turn-on and instantaneous (random) Solid State Relays.

Reliable and high performing, this series are the perfect choice for industrial motors needs. Each product comes with built-in overvoltage protection and IP20 touch safe housing.

cel3pac – SGT range

Our SGT range is designed for frequent start/stop operation of three-phase motors

  • Version with 100 mm installation width,
  • Small footprint: 34.7 mm height,
  • 3 legs control (2 legs control available : SGB serie)
  • Zero cross turn-on and instantaneous (random)
  • Improved connections to increase switching current limits,
  • Increase in the size of terminals on the power side: up to 50 mm²


sightpac – SMT range

Our SMT range of three-phase Solid State Relays is a compact 45 mm version.

• Same fixing distance as our okpac® and celpac® ranges,
• An innovative and scalable range (optional future modules).


AC Motor inverters

Several models of reversers are available in the product range of celduc® relais up to 7.5 kW. They have the interlocking function and over-voltage protections integrated.

SMR range (Compact 45 mm version) is used to reverse the rotational direction of a motor (2.2kW max).

SGR range (100 mm installation width) is designed to control and reverse the direction of three phase motors 7.5kW max @400Vac similar 10HP @400Vac. Interlock feature is included so you can start/stop and reverse operation in a safe mode.

SMR and sGR

Soft Starters

The drawbacks of direct starting are as following:

  1. High inrush current: Heat, flicker risks, energy and installation costs
  2. Noise, arcs: Short control lifetime and maintenance costs
  3. High transient torque: Excessive wear of the coupling parts leading to maintenance costs
  4. Quality problems and product wastes may occur

A Solid State soft starter will then limit the starting current hence saving energy. It will at the same time limit torque for a longer lifetime of mechanical parts.

Celduc® Relais has designed a range of soft starters for AC motors up to 26 kW (wired in Delta).

motor softstarters

Find the suitable solid state relay for your application by contacting our sales team.