haze10
Electrical
- Jan 13, 2006
- 81
Replacing existing MV trip relays with new Multilin 350's.
I have a lot of identical padmount xfrms being fed and would like some recommendations on trip curves.
Xfrms: 1500 KVA padmounts, 4160 delta to 480/277 Y, 3ph, 5.0% Imp.
Feeders: 1x 500 MCM CU 15KV, lengths between 300 and 700 feet.
Xfrms manufacturer is out of business, and don't have, nor can obtain, damage curves and inrush value.
So need best guess.
Xfrms are NOT subject to heavy intermittent loading, more like administration buildings with under 75HP motors for HVAC.
Initial thought is Inst value of 10 to 12, and LT at 125%. Does this seem right?
Also, what curve ANSI, IEEE do you think is most common.
Any help appreciated.
thanks
I have a lot of identical padmount xfrms being fed and would like some recommendations on trip curves.
Xfrms: 1500 KVA padmounts, 4160 delta to 480/277 Y, 3ph, 5.0% Imp.
Feeders: 1x 500 MCM CU 15KV, lengths between 300 and 700 feet.
Xfrms manufacturer is out of business, and don't have, nor can obtain, damage curves and inrush value.
So need best guess.
Xfrms are NOT subject to heavy intermittent loading, more like administration buildings with under 75HP motors for HVAC.
Initial thought is Inst value of 10 to 12, and LT at 125%. Does this seem right?
Also, what curve ANSI, IEEE do you think is most common.
Any help appreciated.
thanks