240 corner grounded to 240/139 wye service

[Birken Vogt]

Isn't that what every 480y/277 Bank would be made from?

In my area 90% of 480/277 are padmount

The few that are pole mount are one big can with 3 bushings in and 4 out

I travel sometimes, and always look at transformers when I go, and I never see 480 3-pot banks in other areas either. But I never leave the West so maybe it is different in the East.

 

[ptonsparky]

As you fly East/West. Look down at those circles. I only had one customer in 40 years that had a pad mount feeding pivots.

 

[electrofelon]

In my area 90% of 480/277 are padmount

The few that are pole mount are one big can with 3 bushings in and 4 out

I travel sometimes, and always look at transformers when I go, and I never see 480 3-pot banks in other areas either. But I never leave the West so maybe it is different in the East.

Strange. I work in the Seattle area as well as NYS....never seen I three phase pole unit in a single enclosure - ever. Every one I have seen is made of 3 277V units Just like 208Y/120 banks.

 

[kwired]

As you fly East/West. Look down at those circles. I only had one customer in 40 years that had a pad mount feeding pivots.

I know of one that is padmount and close to the well primarily because it is 200 HP. There been a few nearby converted to padmount only because of a transmission line being installed sort of made them go underground with the local distribution where following same route.

I also seen one where a 230kV line was on opposite side of road but still causing capacitive coupled voltage on the local distribution lines, which because it is MGN also shows up on secondary neutral conductors to customer wiring. Think they may been better off burying that section of local distribution line as well.

Then there is one that pumps manure through pivot that is supplied by the padmount service via the dairy barn.

 

[winnie]

This bank supplies a 480/277V near the lab that I work at:

The cans are all labeled '250', I presume 250 kVA
-Jonathan

 

[don_resqcapt19]

I never see 480 3-pot banks

There are a lot of them around here, but most are 208Y/120, but a few 480Y/277.

 

[tortuga]

Why is normal 208 wye not suitable?

Basically the specs for the equipment such as large pumps are typically 220-240V AC 3PH Input/Output, so the idea is to convert existing service from '240' delta to '240' wye eliminating several 240D to wye transformers, without the POCO needing to special order anything and minimal work other than re-configuring the service drop and entrance.
I suppose one could do 220Y127 but thats non standard L-L voltage and L-N.
I dont even think the NEC would require the neutral past the service disconnect if everything stayed '240'.
Even if it could be converted to 208 more work would be needed, larger conduit for increased wire size, leads to larger pull boxes etc or a step up transformer would be needed, defeating the purpose of this.

With the 240Y139 idea '240' is standard voltage in the NEC and the 139 is simply not used.
In theory LED lighting drivers with their 100-277V could operate at 139 but I'd keep everything 240V as it is now off the corner grounded.
For the small amount of 120V service/maintenance receptacles there could be a buck transformer off the 139 but whatever is existing is fed off 240.

I don't know what is common, but if the transformers used for 480/277 banks would happen to be able to be re-jumpered in same manner then you would have a unit with ~139 volts at the output

Hmmm thats interesting thanks
and thanks everyone for the discussion.