IGBT based DC Solid State Relays

At celduc®relais, DC power switching under control !

The IGBT based SSR (SDI range) can switch up to 100 A @ 750 VDC nominal in a fast, reliable and safe way.

Here are the main characteristics of this range :

  • Diagnostics and Status outputs indicating to the user, in real time, the status of the relay and the installation
  • 50A and 100A versions, control voltage 24Vdc, 48Vdc, 72Vdc, 96Vdc and 110Vdc
  • Power elements rated and adapted to the extreme conditions of your demanding DC power switching applications.

In every situation, safety operation is preserved :

  • Continuous current monitoring (available for 50A version)
  • Built-in protection against overvoltage and fasts transients bursts
  • Built-in protection against overload and shorts-circuits
  • Built-in over load temperature protection : over-heating should occur, the unit will automatically switch off

This range is suitable for controlling High voltage heaters (Supplied by the third rail or Catenary System). It helps to resolve maintenance problems that you have with your electromechanical contactors and improve the temperature control of your system.

Electrical characteristics

Supply input

celduc®relais offers 2 different versions :

-SDIxxx1700 : 24Vdc and 48Vdc versions

-SDIxxx1710 : 72Vdc, 96Vdc and 110Vdc versions

Output voltage

All products have a wide output voltage range with a typical value of 750Vdc

Switching current

celduc®relais offers 2 different versions : 50A et 100A.

(The load can be connected to – or to +)



Main Functions

All the desired security functions are provided by this product :

-Active Clamp protection

-Current monitoring

-Load short-circuit protection

-Thermal Protection

Active Clamp Protection

The active clamp protects the relay against surges and rapid transients.

active clamp SDI range celduc

  1. In some cases opening the circuit generates an overvoltage caused by induction in  the line and the load.
  2. Without any protection, exceeding 1700V can be destructive. (1700V = breakdown voltage). The active clamp will limit the voltage at the relay output terminals.
  3. During this overvoltage, the energy is redirected by the IGBT towards the load until it is completely absorbed. Then the IGBT is completely released and the circuit remains completely open.

Current monitoring

(or by voltage measurement when the relay is OFF)

A “Diagnostic” and a “Status” outputs indicates to the user, in real time, the status of the relay and of the installation.

This function can detect several faults:

1-Open Mains or Open Load detection (or fuse or circuit breaker failure)

open mains detection

When this fault is detected, the Diagnostic output is activated (contact is closed).

2- Leakage current exceeded detection

When this fault is detected, the Diagnostic output is activated (contact is closed).


Load short-circuit protection

Our SDI range has a built-in Load short-circuit protection.

short-circuit protection

  1. The current is stabilized at nominal value in normal operation
  2. A short circuit on the load causes an increase of the current up to the detection threshold
  3. We then open the IGBT in a few microseconds to ensure the power is cut and the current is extinguished.The short-circuit detection shouldn’t be repeated. After 4 detections by the relay, the IGBT state is locked, which will be kept open regardless of the state of the control input.In this case, we recommend that you check your installation and the product is unlocked by resetting the auxiliary power supply.

Thermal Protection

A temperature sensor directly implemented in the IGBT makes it possible to limit the maximum temperature which could destroy the product or lower its lifespan.

Life-Time expectancy

According to calculations made in accordance to ISO13849-1 standard, we get :

MTTF = 118 years

MTTFd = 236 years

MTTFd  (in case of extreme use) = 24 years


All products are designed, tested and manufactured in compliance with the strictest international standards and always with reliability and safety in mind.

All of our relays okpac® SO (as well as SC relays), celpac® 2G SU/ SA (including the current sense module ESUC) but also the 2-phase SOB and 3-phase SGT comply with the European standard EN 61373 for railways : shocks and vibrations tests on relay.

Regarding the standards about Fire behavior and fumes NF F16-101, NF F16-102 and EN 45545 calling for the EN 60695-2-10/11/12 (Glow Wire tests (GWFI –GWIT), blue and black plastic covers and encapsulating resin of SO and SU/SA relays are classified.

Our products are also compliant with the EN 50155 standard which applies to all electronic equipment for control, regulation, protection and power supply used on rolling stock.

EN 50155 : Operation, design, documentation and testing requirements for Electronic equipment used on rolling stock

EN 50124-1 : Insulation coordination for all electrical and electronic equipment used on rolling stock

EN 50121-3-2 : Electromagnetic compatibility for all electrical and electronic equipment used on rolling stock

EN 45545-2 : Requirements for fire behavior of materials and components used on rolling stock

Available Products

SDI0501700 – 50A / 12-940VDC / 1700V / Cde 24-48VDC

SDI0501710 – 50A / 12-940VDC / 1700V / Cde 72-110VDC

SDI1001700 – 100A / 12-940VDC / 1700V / Cde 24-48VDC

More information needed ? contact our technical experts