Fused Contactor without Overload Relay
Fused Contactor without Overload Relay
(OP)
Hi All,
I have run into an existing installation where a 4.16kV Fused Contactor (360A) with 100E fuses feeds a 500kVA 4.16kV/480V transformer. There is a zero sequence CT and ground fault relay for the feeder which trips the contactor but there isn't any overload relay nor phase CT's. This is rather strange for me as there is no overload protection provided on this feeder cell. The fuses will only interrupt the higher fault currents but won't provide overload protection. On the 480V side there is a 600AT circuit breaker. In an overload situation the 600AT breaker would trip, line-line faults would be covered by both the fuse and the 600AT breaker, and line to ground faults will be covered by the ground fault relay opening the contactor. Looks like all the bases are covered.
Are there any issues here? I would imagine that a manufacturer wouldn't build something like this if it was a safety concern. It's just something I have never seen.
Please let me know your thoughts on this.
I have run into an existing installation where a 4.16kV Fused Contactor (360A) with 100E fuses feeds a 500kVA 4.16kV/480V transformer. There is a zero sequence CT and ground fault relay for the feeder which trips the contactor but there isn't any overload relay nor phase CT's. This is rather strange for me as there is no overload protection provided on this feeder cell. The fuses will only interrupt the higher fault currents but won't provide overload protection. On the 480V side there is a 600AT circuit breaker. In an overload situation the 600AT breaker would trip, line-line faults would be covered by both the fuse and the 600AT breaker, and line to ground faults will be covered by the ground fault relay opening the contactor. Looks like all the bases are covered.
Are there any issues here? I would imagine that a manufacturer wouldn't build something like this if it was a safety concern. It's just something I have never seen.
Please let me know your thoughts on this.






RE: Fused Contactor without Overload Relay
Under fault conditions, including internal transformer faults, the fuses will provide protection.
Bill
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"Why not the best?"
Jimmy Carter
RE: Fused Contactor without Overload Relay
RE: Fused Contactor without Overload Relay
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Fused Contactor without Overload Relay
"Will work for (the memory of) salami"
RE: Fused Contactor without Overload Relay
RE: Fused Contactor without Overload Relay
old field guy