Originally Posted by
mixedgas
You just switch the load. NO dpdt required.
The requirement is for a simple loop, with double switches only on the access panels, ie two microswitches in series on the removable panels, to prevent failure if the switch sticks. But many systems only end up with one switch anyways, and if you use a nonstandard security screw, and word your variance carefully, you can even get rid of the "In Projector" sensing portion of the interlock and just have a shutter inside. Since the keyswitch is for the operator, there is no requirement for redundant keyswitches. Belive it or not, the emission indicator and key is not for the public, nor physical security, it is to help the operator know the status of the system! At least thats what the relevent advisory letter says.
Steve