Trapped Key Exchange Systems

A trapped key exchange system is a simple and affordable way to increase the safety of doors and hatches. The only necessary wiring is a keyed switch on the front of the control panel to isolate power. There are no long and expensive runs of wiring to the doors or hatches required. We have clients from many industries taking advantage of this simple solution. Here is an example of how a system might work:

A keyed switch is added to the control panel. These are typically 20A, but higher current ratings are also available. To remove the “power isolation” key, the switch has to be opened. This isolates the hazardous load and prevents it from being energized until the key is returned.

The power isolation key is then taken to the interlock at the door or hatch. When the key is inserted and turned in the interlock, the door can be opened. When the door is opened, the key is trapped, and as long as the door remains open, the key cannot be removed or returned to the control panel.

In the example below, we have included an additional “safety” key that has to be removed in order to open the door. This key would be kept with the person entering the door or hatch and is intended for full body access areas. Until the safety key is returned, the power isolation key from the control panel is trapped and cannot be removed. In many applications, several safety keys can be released, so that several people can enter the hazardous area. Until all of the safety keys are returned there is no way to release the power isolation key that allows the hazardous load to be energized.

There are countless ways to configure an interlock system. Let us know if you have an application you would like to discuss. We are happy to help.

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