SIL4 Timer relay

Delay the attraction of a signaling relay N.S1

Timers are used to delay the attraction of a “N.S1” type signaling relay. They are usually used with track circuits to suppress possible nuisance releases caused by point-and-track kills.

Placed as an interface between an N.S1 relay and its command, the relay can only energize after a continuous command of a selected minimum duration. Any disappearance of the command, however short, resets its time delay and drops the relay if the latter is active.

This block has a SIL4 security level. In the absence of a command, no fault can cause the output relay to energize. Also, no faults can shorten the selected time delay.

BKFU Relais N.S1 Agence Marseille SCLE
BTE relais N.S1 Agence Marseille


  • Hides short commands, thus avoiding untimely excitations and relay “chattering”
  • For track circuits, delays release of tracks
  • Guarantees the absence of immediate excitation of the relay on the appearance of the command
  • Can delay the activation of a permissive signal, control push button or other


  • Safely filters out shunt-type command noise
  • SIL 4 safety level
  • Signaling device powered by 24V DC from the substation
  • Galvanically isolates the control output relay supply and the substation supply
  • Robust, this device is very reliable and available
  • Maintenance-free, its case and connections are in
  • N.S1 format, simplifying exchange in the event of a failure


SNCF Réseau

Downloadable files

Contact a sales representative

for more information

Nathalie Sévikian

+33 4 91 03 04 24 rf.elcs@naikives.eilahtan


Stay in touch!

Subscribe to our newsletter

Our certifications

Any question?I would like to be contacted