If I am trying to run (2) 480 volt garage heaters each pulling approximately 10 amps and my service is 120/208v
I have a 30 kva transformer and I am backfeeding it with 50 amps on the secondary or 277/480v side.
? How do I calculate the availble current on the primary or 120/208v side.
What I am experiencing is that the fans run but the heaters are not really heating they just warm up a little.
Now keep in mind these are used heaters and they are about 15 years old.
? could it be that the heaters are bad or am not feeding my transformer right.
From the title of your post, 277/480v delta, this is not a delta connection. Back feeding, you mention the 277/480v side? Confusion here could lead to a wiring issue. Help us understand what you really have.