Range of application

The solenoid interlocks ensure that sliding, hinged and removable guarding devices, such as grids, hoods or doors, cannot be opened until dangerous conditions (e.g. run-on movements) have been terminated. This takes place in co-ordination with the control system of a machine. Fail-safe standstill monitors or delay timers monitor run-on movements or time sequences. These solenoid interlocks are also used for cases in which the opening of a guarding device represents a non-permissible intrusion in a production process.

In combination with the SRM range safety relay module, the solenoid interlocks achieve SIL 3 according to EN 62061 and PL e according to EN ISO 13849-1.

Design and operating principle

On the solenoid interlocks, the switching element with interlock is not physically connected to the actuator but functionally united or separated on switching.  When the guard device is opened in the uninterlocked condition, the actuator is separated from the base unit. In the process, NC contacts are positively opened and NO contacts closed. The machine control circuit is only activated when the actuator has been inserted into the interlock and is interlocked. The solenoid interlocks operate on the principle of »actuated without power supply«, whereby the actuator is held in the interlock by spring pressure. When power is supplied to the solenoid, the interlock is released. The guarding device can then be opened. The solenoid interlocks with the power-to-lock principle work in the opposite way.

The solenoid interlocks shown in this chapter bear the CE mark according to the Machinery Directive 2006/42/EC.


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On sliding guards
On hinged guards
On removable guards