New Compact High Voltage DC Solid State Relays

celduc® relais, leading manufacturer of Solid State Relays, today announces it has developed a new High Voltage DC Solid State Relays range designed to control resistive loads : SMI Series.


Self-protected integrated solution

The SMI Series is available for loads up to 750Vdc/15A*, with typical input voltage 24Vdc.

Beside its compact housing of 45mm installation width, our SMI has a Status output indicating to the user, in real time, the status of the relay and the installation.

Other important capabilities include built-in protections :

  • Built-in protection against shorts-circuits. A short circuit on the load causes an increase of the current up to the detection threshold. When it occurs, the power element is opened in a few microseconds to ensure the power is cut and the current is extinguished. The Status output of the SSR is then activated, to indicate, in real time, the status of the relay and the installation.
  • Built-in UVLO (Under Voltage Lock Out) protection which triggers a lock-out in the event of undervoltage of the auxiliary or main supply voltage.
  • Built-in protection against surges and rapid transients (Active clamp) : Without any protection, exceeding 1700V can be destructive (1700V = breakdown voltage), therefore it is necessary to have a built-in active clamp protection which limits the voltage at the relay output terminals. It means that during an overvoltage, the energy is redirected by the power element towards the load until it is completely absorbed. Then the power element is completely released and the circuit remains completely open.

Thanks to its strong input/output insulation, this DC Solid State relay is designed to meet the extreme conditions of railway applications.

To control High voltage heaters

Typical applications are the control of High voltage heaters supplied by the third rail or Catenary System. Thanks to this new product you will resolve maintenance problems that you have with your electromechanical contactors and improve the temperature control of your system.

The specifications of the SMI Series include:

  • “Push-in” spring type power connectors : Simple connection and no need of preventative maintenance (tightening of connections).
  • Typical input voltage : 24Vdc
  • Output voltage Typical value of 750Vdc
  • Switching current of 15A*
* we remind you that a solid state relay must be mounted on heatsink in order to reach rated performances.

celduc® relais offers “Ready to use” version with built-in heatsink.

SMI with built-in heatsink

The SMI Series adds to the portfolio of High voltage DC SSRs, which already includes our SDI, IGBT based DC Solid State Relays.

To learn more about the SMI Series of compact DC solid state relays, check out our new product video :