What's new
What's new

Interpret this transformer label


Jan 28, 2012

I need a Delta-Wye transformer, and I need to step up from 240v to 600v*.
I found this one used, the only thing that is a bit confusing is the primary is listed as 600v and the secondary as 240v. However the diagram and the labels seem to suggest it is a step up, and that is what the seller says it is.
The 240v is labeled as H, shown in delta (correct?)
The 600v is labeled as X, shown wye (correct?), the 347v would also make sense for voltage between line and ground.
Which means it's a step up transformer?

While cheaper than new, it's not that cheap that I want to end up with a paper weight, so looking for confirmation.
New one is $3000 (copper) CAD, this surplus/used one (aluminum) is $2200 CAD.
*In my other thread I said I needed 480v, turns out the machine I purchased accepts up to 600v, and since I have other 600v equipment I figured I might as well go to 600v. The other 600v motor is currently fed from 240v-600v single phase transformer to a VFD. I can't use this approach with the new machine since it has several motors to power.

Generally, transformers will work fine in either direction. Use one set of windings as the primary, it steps up. Use the other set of windings as the primary, it steps down.
The manufacturer labeled this one as a 600Y-to-240delta transformer. From the label, I don't see any reason you can't operate it as a 240delta-to-600Y transformer.
I have absolutely no idea if this xfmr will work for your needs, however, from a negotiation standpoint I’d offer 50% of new.

Step-up xfmr has to be a niche thing barring Home Shop Harry’s. I’d offer $1500 if you really want this.

Anyone else confused by the Sec being H and the Pri being X?
I bet you could accomplish the step-up you need a lot cheaper than $1500 Canadian, using two single-phase transformers in an open-delta arrangement. Also, how much kVA capacity do you need?
"Usually" at thet kVA level it would be reversible at leasrt as far as turns ratio. Lower power ones are sometimes "compensated", which means in reverse they produce a lower output voltage than expected (not the rated input).

The H and X are screwy. The delta would be the normal high voltage and primary. Not a lot of things NEED a delta on the output. Not a lot of things USE wye on the input. You would need to corner-ground the delta is used in reverse.
You would need to corner-ground the delta is used in reverse.

Thanks, I missed that detail.

I'll be feeding this from a Phase Perfect, from their FAQ:

Why is the output voltage on one leg of my 240 V phase converter 208 V to ground?

A: For a phase converter to generate three-phase power, the two incoming power lines are directly passed through to the output and the phase converter generates the third leg in a configuration known as “high-leg delta.”

My bit of googling has high leg != corner grounded. So in the interest of not damaging the electronics that will get hooked up to this transformer I should just by the new one?

Do I need to tell the transformer manufacturer that the delta input is high leg? This is the quote I got:
I bet you could accomplish the step-up you need a lot cheaper than $1500 Canadian, using two single-phase transformers in an open-delta arrangement. Also, how much kVA capacity do you need?
Normally I'm pretty cheap and if the machine was only a simple motor that I could replace, I'd be interested in pursuing something like this, but the "machine" is an industrial robot with a control cabinet full of electronics that the manual states it wants wye configured source. At this point between the machine and the 20hp Phase Perfect I'm into it for a good used car so no stopping now :). The Phase Perfect lists the KVA as 26.6, so 30Kva is the next standard size. I did contact PP and they said 30Kva would be OK. I will have to put the converter into "transformer mode".

Thanks everyone.
I would not want to connect corner ground to any electronics, mostly because there may be transient suppressors that may not like the high voltage to ground.

Also, I am now aware that some units (one was posted recently) use an input autotransformer, non-isolating. They may not like the high voltage either.

You are probably going to find that almost nothing and nobody likes corner grounding except a motor, or another transformer. Even there it is possible to run into insulation voltage rating issues.

Late to the party but curious: what's with the 347/600 designation on the primary?
Wye/delta voltages.
The delta-connected 240V windings are going to be your primary. They don't need to be grounded, because they're connected to the existing 240V electrical distribution system. Grounding them would in fact produce a nice big bang given you're essentially grounding one of the two 120V legs of your supply, or the P-P output.

The 'secondary' is a 347/600Y supply. It's isolated until you ground it. Ground the centre point (X0) and you have a nice balanced 347/600Y supply same as any utility will give you (at least as long as the P-P output is balanced).

The P-P having a high leg isn't an issue; the transformer doesn't care as the delta windings only see line to line voltages, and insulation voltage shouldn't be an issue on the 240V side.
the diagram is only drawn like that as im guessing the taps are set up inside just like the photo so nobody gets confused and hooks things up backwards.
Techically any transformer can go in reverse.
Primary is ususally the input source voltage.
Secondary is usually the ouput voltage
Most end up using an auto transformer for step up voltage as it allows the voltage to be more stable, isolation transformers are used for step down so that the high voltage is a seperate winding and ususally cost more, and prevents high voltage from going through and causing electrocution if touching grounds etc.

auto transformers have less voltage loss and are more efficient and stable voltages.
Yes, you would only need to corner ground if delta was an output. As an input you would nearly always connect as delta, meaning not grounding the "neutral" if a wye winding used as an input.

As for the PP, with it being high leg, some things will not like the output. Motors and transformers (if delta or delta connected) will not care.