Wiring a Safety Input to PL d: the Device, the Two Channels and What the Relay Expects

Three subsystems of a guard stop function drawn left to right: the interlock device feeding two channels into a 440R-D22R2 relay and the relay driving two contactors with mirror contacts back into the reset loop, with the quantity each subsystem contributes named underneath

Four guard doors on a packing cell, a Trojan T15 tongue switch on each, 440K-T11390, all four pairs of contacts daisy-chained into one 440R-D22R2 relay, and the calculation for that stop function will not go past PL c. Every switch in the chain has its two direct-opening N.C. contacts, the wiring matches the drawing, and … Read more

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