Micah_68
Member
Maybe someone with UL experience can settle something for me. In a UL508A listed panel, do you have to interlock the coil of a self protected combination motor controller?
On NEMA style starters you always see the coil interlocked with the overload contact, so that in an overload condition, the contactor breaks the power conductors.
On the newer IEC style self protected combination starters, the overload/circuit breaker section physically breaks the power conductors in an overload/short circuit condition, so I wouldn't think the coil interlock is necessary, but I have seen it quite a bit.
I can't seem to find anything in UL508A (control panels) or UL508 (equipment) specs that definitevly says either way. What say you?
On NEMA style starters you always see the coil interlocked with the overload contact, so that in an overload condition, the contactor breaks the power conductors.
On the newer IEC style self protected combination starters, the overload/circuit breaker section physically breaks the power conductors in an overload/short circuit condition, so I wouldn't think the coil interlock is necessary, but I have seen it quite a bit.
I can't seem to find anything in UL508A (control panels) or UL508 (equipment) specs that definitevly says either way. What say you?