Ungrounded 600v system to grounded system

[Dsg319]

We re-worked some power to a remote location roughly around 1500 feet long run. It’s was 240v direct buried 2awg aluminum.

But there is now some added load at the end so a 600v 120/240v transformer was added to step up right after the service than step back down at the location.

I know it’s not a proper step up transformer rather than back feeding it which is where the problem arises.

The 600volt conductors are ungrounded and have no detection system. Rather than proposing a ground detection system I am going to go with either grounding the center tap of the primary winding (600v) .

Can anyone see a problem with this?

It’s a 10kva tranny. Primary protection before the transformer is at the service on the 240volt side.

Conductors go straight to the other transformer nothing in between. No disco or ocpd inbetween. Is any needed for the 2nd tranny? I know we can label where the lockable disconnection means is. But can the same disconnect work for both transformers.

Another problem I see is once the conductors are stepped back down to 120/240v they terminate directly into a main lug only panel. I was under the assumption they must terminate into a single breaker or fuses. Or can the breakers not just add up to the allowed sum of the single breaker?

Below is the tranny nameplate.

 

[Dsg319]

Below is a sloppy thrown together set up of what it is currently there.

 

[jim dungar]

...problem I see is once the conductors are stepped back down to 120/240v they terminate directly into a main lug only panel. I was under the assumption they must terminate into a single breaker or fuses. Or can the breakers not just add up to the allowed sum of the single breaker?

The conductors, on the transformer secondary are subject to the rules in 240.21(C).
The old rules have changed, terminating in a main lug only panel is no longer allowable.

 

[Dsg319]

The conductors, on the transformer secondary are subject to the rules in 240.21(C).
The old rules have changed, terminating in a main lug only panel is no longer allowable.

Thank you.

 

[LarryFine]

The 600volt conductors are ungrounded and have no detection system. Rather than proposing a ground detection system I am going to go with either grounding the center tap of the primary winding (600v) .

What you're referring to as the center tap on the 600v side is actually a tap jumper for voltage adjustment. I don't know whether it is acceptable to bond it to the EGC. In any case, that connection should be left unconnected at the second transformer. Bonding one line conductor would work if the wire voltage rating isn't stressed.

 

[Dsg319]

What you're referring to as the center tap on the 600v side is actually a tap jumper for voltage adjustment. I don't know whether it is acceptable to bond it to the EGC. In any case, that connection should be left unconnected at the second transformer. Bonding one line conductor would work if the wire voltage rating isn't stressed.

Good point if it were a center tap it would be 300/600v. And yes just making one bond at the first transformer.

Ive never done a step up/ step down configuration before. If it was completely up to me I would have ocpd at the back fed step up transformer on the 600v side.

Is that compliant to only have it on the 240volt side back feeding the transformer.