Electrician Talk banner

Can autotransformer be used for distribution?

1139 13
Can I use a 600/208 autotransformer for distribution? I have 347/600Y supply coming to a machine shop and need to step down to 120/208y for 400 amp 3-phase panel. 150 KVA autotransformer is readily available. Rule CEC26-266 2(a) seems to say I can and i can't. I do have a solidly grounded neutral available from the primary feed. Is this setup acceptable in Canada?
  • Haha
Reactions: RUSKES
1 - 2 of 2 Posts

396 Posts
Gotcha. Thought you meant available, as in at the supplier. Also thought you'd said 200a.

Not sure if there is anything in the cec on it.(I'm without a code book at the moment) But I was always told it's a bad idea to use them as a step down. Faults will run right through them causing high circulating currents. If a winding shorted you could end up with higher than expected voltage on the low side as well.
Only ever wired small ones to step up voltage at a specific piece of machinery.
1 - 2 of 2 Posts