SIL4 certification for CLEARSY RS4 vital latching interface system

17 June 2021

CLEARSY has developed its own range of vital relays, called RS4. In 2016, All CLEARSY vital relays were SIL4 certified, the highest safety integrity level according to EN 50129. Today, they are used with success as interface relays for vital programmable logic controller in signalling applications.

In signalling, relays are also used to materialize interlocking logic. In order to allow use of RS4 relays in interlocking logic, CLEARSY has been working on a SIL4 vital latching interface system. Job is done! RS4 vital latching interface system has been certified SIL4 by CERTIFER and is ready for commercialization.

The RS4 latching interface system is proposed as module of 24 weld no-transfer “right” contacts and 24 weld no-transfer “left” contacts. As required by EN 50129 standard, it guarantees that if one or more contacts weld, the internal latching relays will not actuate from the position where the welding occurred. In addition, the system latching feature allows keeping the status imposed by the latest command. The modules are packaged in 6U card and it can be combined with other RS4 latching interface system modules in order to reach 240 “right” and “left” contacts (10 modules are combined). Combining modules makes all signalling applications possible. Finally, modules are powered in 24VDC.

With the addition of the SIL4 vital latching interface system, RS4 range is now complete and ready for its use in relay based interlocking logic. Combining its railway safety knowledge and short supply delays with a standard and compact packaging (6U card), CLEARSY proposes new convenient solution to the rail industry for safety critical application like interlocking (Day/Night switch, Route latch function, Switch machine safety latch).