What size breaker for a 7.5KVA transformer

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Mrat

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Granite Bay, California
I will have 480V supplying a 480V/240V 7.5 KVA transformer. I have 240V and 120V output taps. My loads will be very lite, I just had this transformer sitting around for this voltage and wanted to use it. It was used before tapped directly into the feeder wires from a 100 amp breaker supplying a pump motor control. The output of the transformer supplied a small subpanel with various breakers, typical was 20 amp.

The new configuration will have 2 subpanels: one to feed a 480V 3 phase motor and also a 2 pole 240V for the transformer. The transformer will feed the 120/240V subpanel. I know I could use (I think) a much bigger breaker then the 15 amp 2 pole I was planning to supply power to this transformer since the transformer output is protected by a breaker. Any ideas. Thanks

Moderators note; moved from Grounding versus Bonding Forum
 
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Mrat said:
. The transformer will feed the 120/240V subpanel. I know I could use (I think) a much bigger breaker then the 15 amp 2 pole I was planning to supply power to this transformer since the transformer output is protected by a breaker. Any ideas. Thanks

Moderators note; moved from Grounding versus Bonding Forum
Click to expand...

Mrat,With secondary protection set at 125%, Primary can be set at 250%.
Rick
 
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