480V to 240V Transformer

[kurt.brinker]

IMO the secondary needs to be grounded. Whether at a corner or at the mid-point of a winding(if you may need 120). Otherwise the unbalance you are going to create is going to make this thing do some funny stuff. What are you connecting to the secondary of this transformer??? Should have a disconnect or panel according to the transformer tap rules in NEC 240. And yes you would install a system bonding jumper either at the transformer or disconnect that would bond X4 to the chassis, grounding electrode & neutral. There are alot of rules for seperatley derived systems make sure you bone up on them.

the secondary goes to a 20A circuit breaker inside a panel and then to a terminal strip inside the building. It then powers a flowmeter, plc, and some other little devices. the only lead of the transformer grounded right now is the one that was grounded when i took the lid off. I am assuming its the ground that runs in the middle in the picture. What is the bonding jumper you are talking about? Do i need to put X4 to the chassis ground on the transformer along with my load ground and 480V ground?

 

[kurt.brinker]

just to follow up.

I emailed acme tech support and they said i just needed to use X1 and X2 for single phase 240 and thats it. My kva rating is now 5 instead of 15 but i still have ample capacity. Thanks for the help.