The scenario
A machine safety circuit uses multiple emergency stop pushbuttons wired in series to de-energize a safety relay when any E-stop is pressed; a momentary reset button with seal-in contact re-energizes the relay after all E-stops are released.
What is in this drawing
Read the decisions behind it.
01
Wired NC E-stop inputs use XIO contacts so the rung is false when any stop is opened
02
Reset and auxiliary seal-in are ORed in a parallel branch to latch the safety relay
03
Separate pilot lamp rung indicates safe relay status without complicating the safety rung
Use for any hardwired emergency stop control circuit requiring multiple stop stations and a manual reset, as in machine guarding, conveyor, or robotic cell safety systems.
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