How to Transform 240v high leg to 480v

[Idaho Electric]

Hello I have a customer who is wanting to have a tool install that takes 480v 3p. There current service is a 240v high leg. I wanted to know if there is a transformer that will work in this application. I’ve been told a delta to delta transformer would work and I was also told I can install a buck boost transformer on the high leg to even out the voltage.

The equipment draws only 6amps

 

[hillbilly1]

Hello I have a customer who is wanting to have a tool install that takes 480v 3p. There current service is a 240v high leg. I wanted to know if there is a transformer that will work in this application. I’ve been told a delta to delta transformer would work and I was also told I can install a buck boost transformer on the high leg to even out the voltage.

The equipment draws only 6amps

You do not need to boost the high leg, it does not matter with line to line loads. A delta wye transformer would be a better choice than a delta delta.

 

[CoolWill]

A transformer with a delta output will need to be corner grounded or have ground detectors. You could use three single phase 240-480 transformers for such a small load and configure them delta-wye.

 

[infinity]

I agree with Hillbilly, et al. A 240-480, Delta/Wye step up transformer is the simplest option.

 

[jim dungar]

A transformer with a delta output will need to be corner grounded or have ground detectors. You could use three single phase 240-480 transformers for such a small load and configure them delta-wye.

A delta-wye stepup configuration would require (3) 240-277V single phase units.

You can completely ignore the wild leg, as the neutral is not brought to the transformer.

 

[MTW]

Hello I have a customer who is wanting to have a tool install that takes 480v 3p. There current service is a 240v high leg. I wanted to know if there is a transformer that will work in this application. I’ve been told a delta to delta transformer would work and I was also told I can install a buck boost transformer on the high leg to even out the voltage.

The equipment draws only 6amps

What does the load /tool consist of ? That could make a difference on which way to go.

 

[Little Bill]

I agree with Hillbilly, et al. A 240-480, Delta/Wye step up transformer is the simplest option.

Is the Wye configuration so it can be center grounded?

 

[infinity]

Is the Wye configuration so it can be center grounded?

Yes. I prefer the KISS principle and this scenario doesn't warrant messing with an ungrounded or corner grounded system.

 

[LarryFine]

Plus many electronic machines prefer balanced to-ground voltages.

 

[CoolWill]

A delta-wye stepup configuration would require (3) 240-277V single phase units.

You can completely ignore the wild leg, as the neutral is not brought to the transformer.

Yes, you're absolutely correct. My brain wasn't in gear.

 

[kwired]

Customer equipment being supplied can possibly factor into which method is best . If something with a VFD or other electronic items connected directly to the supply voltage then a wye secondary might be about the only option or at least the best option. There are drives that will work on corner ground but you need to disable the line side surge protection as it was only designed for 277 nominal to ground on all three input lines.

If it is a fairly basic motor operated item, it probably fine on corner ground or even high leg delta - yes you can still ground mid point of one side of 480 delta, though really not a lot of advantage of doing so. It gives you 240/480 on two sides of the delta and a 416 volt high leg. Still a problem for VFD's that have 277 volt surge protection.

An advantage with delta secondary is you can use two 240/480 single phase secondary transformers and connect in open delta configuration, which may be just fine with this fairly limited load. Will need larger units than if you had three but may still cost less to do it this way.

 

[tortuga]

The last time someone wanted me to get a 480 machine ( a platen press) running on 240, the least expensive option was to covert the machine to 240V, only thing I had to do besides re-labeling was change some motor leads, change a tap on the control transformer and replace the heater elements.
Fortunately I had the help of good documentation and the company that made it sold me what was needed, including a new nameplate.

 

[hillbilly1]

Is the Wye configuration so it can be center grounded?

Yes, also if the equipment has a freq drive, it will play with it better.

 

[Birken Vogt]

The last time someone wanted me to get a 480 machine ( a platen press) running on 240, the least expensive option was to covert the machine to 240V, only thing I had to do besides re-labeling was change some motor leads, change a tap on the control transformer and replace the heater elements.
Fortunately I had the help of good documentation and the company that made it sold me what was needed, including a new nameplate.

Yes. The amount of expense some people go to, in order to install transformers, etc. for machines or from generators, when it could be converted and not have any transformer burning up power all the time.

 

[kwired]

Yes. The amount of expense some people go to, in order to install transformers, etc. for machines or from generators, when it could be converted and not have any transformer burning up power all the time.

Would be first thing I would be looking into as well in most cases. Three phase motors under ~60 HP often are dual voltage and easily convertible. Might be out of luck with two speed motors or anything that was rewound and they did not bring all the leads out when they rewound it.