Relays with forcibly guided contacts are specified wherever the logic of an application wants to detect the state of the contacts of a relay and use it for control purposes. Such relays enable the implementation of self-monitoring systems.
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Because these relays are used in safety critical applications, relays with forcibly guided contacts are subject to special requirements, which are summarised in the standard EN50205. This standard specifies that the switching relays must feature at least one NC and one NO contact.
The contacts are mechanically interlocked in such a way that the NC contact and the NO contact can never be closed at the same time.
This applies over the entire life span for contacts under load and no load conditions. Apart from this it must be guaranteed that open contact distances of at least 0.5mm exist over the full life in normal operation as well as in any case of relay failure. All newly developed relays of ELESTA relays GmbH have gained TÜV approval for compliance with this standard, i.e. they meet the latest requirements applicable to relays with forcibly guided contacts.
