I've got a single 13.8kv feeder running out to two 2000kVA xfmrs, each with a fused disconnect. Xfmrs are Delta-Wye. Secondary is impedance grounded 480V, 10A NGR.
How do you protect against phase loss in the event a primary fuse blows? I'm having a hard time getting my head around what the output looks like with one phase out.
The feeder CB has a pretty sophisticated relay, and I think I can see the imbalance with the 46, 47, 60 functions, but I don't want to trip the feeder, cause I want the other xfmr to stay in service.
The transformers also have a versitile trip for the secondary OCPD, and I'd like to take the affected xfmr off-line with the secondary CB.
Oh yeah, I want the xfmrs to stay on-line if they get a grounded 480 phase, so current imbalance is not necessarily a reason to trip.
Anybody got any references?
(searching for my college copy of Stephenson)
How do you protect against phase loss in the event a primary fuse blows? I'm having a hard time getting my head around what the output looks like with one phase out.
The feeder CB has a pretty sophisticated relay, and I think I can see the imbalance with the 46, 47, 60 functions, but I don't want to trip the feeder, cause I want the other xfmr to stay in service.
The transformers also have a versitile trip for the secondary OCPD, and I'd like to take the affected xfmr off-line with the secondary CB.
Oh yeah, I want the xfmrs to stay on-line if they get a grounded 480 phase, so current imbalance is not necessarily a reason to trip.
Anybody got any references?
(searching for my college copy of Stephenson)