FaradayFF
Senior Member
- Location
- California
Hi Guys,
Can I use an undersized breaker to protect a dry-type, one phase transformer if I'm only loading a fraction of the transformer. Say I've got a 100kVA transformer, 480V on high side, and utilize a 100Amp breaker. The loading on the transformer would be around 20Amps max. My concerns is the inrush current. Does the transformer get its max. inrush current value regardless of the load connected to it on the secondary?
The NEC allows to go up to 125% max. to select OCPD on the primary, but since I'm not going to load up the transformer to its nameplate rating, I'd like to use a smaller breaker(oversized xfmr situation).
Thanks,
EE
Can I use an undersized breaker to protect a dry-type, one phase transformer if I'm only loading a fraction of the transformer. Say I've got a 100kVA transformer, 480V on high side, and utilize a 100Amp breaker. The loading on the transformer would be around 20Amps max. My concerns is the inrush current. Does the transformer get its max. inrush current value regardless of the load connected to it on the secondary?
The NEC allows to go up to 125% max. to select OCPD on the primary, but since I'm not going to load up the transformer to its nameplate rating, I'd like to use a smaller breaker(oversized xfmr situation).
Thanks,
EE