Safety critical relays

The safety-critical relay portfolio comes from safety rolling stock applications such as automatic braking units (ATB) or automatic train operating systems (ATO). There is an increasing interest to use this proven technology in trackside signalling applications because it is space saving and very economic. Some examples of applications of these relays are: electrical control point machines and level crossing.

 

There are four groups: general purpose relays, semi-vital relays, safety-critical relays and vital relays. Unique relay features such as spring enchanced gravity function in combination with ‘non-weldable’ double make - double break contacts and weld-no-transfer function ensures compliance with the highest safety demands.

 

The design criteria for rolling stock safety-critical relays are severe DC voltage switching with inductive loads (8 - 12 A at 110 - 125 VDC, L/R = 40 ms), long life = 100 million operations, extremely high MTBF values, compact size, working temperature -40 °C...+80 °C and resistant to highly humid and corrosive environments.

 

Main advantages of safety-critical relays: