Contact Expansions
Contact expansion relays are used to increase the number of safe outputs of a safety relay or a safety PLC. This is useful in applications where several machines need to be stopped by one safety function.
For example, a safety relay with 3 NO contacts: If the risk assessment requires the highest level of safety (PL e/SIL3), two of the NO contacts are needed in order to safely control the power to one machine. If there is a second machine that also needs to be stopped, the third NO contact can be connected to an expansion relay, from which 2 new NO contacts can be used to control power to the second machine.