L
Lunnon, Robert
It depends on the application and varies by country...
The rules of thumb I use are. The E-Stop should be electrically interlocked, here in OZ the regs say that "power must be removed from the dangerous
elements".
Secondary interlocking is not allowed, this means no PLC involvement and that the interlock must isolate the offending power circuit directly with no intervening electronics to go wrong (Unless safety rated of course).
A PLC may be used to monitor the state of the E-Stop only.
All interlocking components must be safety rated.
Bear in mind that a machine with large amount of inertia may be safer to brake dynamically or mechanically. Allowing such a machine to coast to a stop may risk considerable further injury. Mind you with some of the equipment I have built it is a matter of how far you will have to walk to
retrieve your arm :=)
The rules of thumb I use are. The E-Stop should be electrically interlocked, here in OZ the regs say that "power must be removed from the dangerous
elements".
Secondary interlocking is not allowed, this means no PLC involvement and that the interlock must isolate the offending power circuit directly with no intervening electronics to go wrong (Unless safety rated of course).
A PLC may be used to monitor the state of the E-Stop only.
All interlocking components must be safety rated.
Bear in mind that a machine with large amount of inertia may be safer to brake dynamically or mechanically. Allowing such a machine to coast to a stop may risk considerable further injury. Mind you with some of the equipment I have built it is a matter of how far you will have to walk to
retrieve your arm :=)
