Power configuration for 480v 240v 3p & 1p

[ADP]

I need to consider what is the best, most efficient and cost effective configuration to provide for my customer’s needs.
He needs 480v, 240v and 120v both 3P and 1P for his loads.

Currently he has 400A 1P service with 2 panels for all his loads.

He’ll have a food/juice processing shop.

- 3 fridge containers each @: 480v 3p 3kW.

• 2 compressors each @: 230v 3p 7.5kW. - food processor @: 220v 3p 12.68kW.
• future food processor @ 220v 3p 12.68kW.

• 2 air units each @: 240v 1p 2.2kW.
• 4 air units each @: 240v 1p 5.5kW.
• lights & misc total @: 120v 1p 6kW~

Using this formula kW/V/1.732=
480v 3P = 11A

230v 3P = 102A

240/120v 1P = 160A


Changing service to 480v 3p and stepping down with xfmr seems overpriced.

So I’m thinking, will it be best to

• step up with 2 xfmrs, (480v 3p & 240v 3p),
• 1 xfmr 480 3p and 1 RPC for 240 3p,

Or
- 1 xfmr 480 3p and VFD for the 240v 3p equipment?

What are you guys’ thoughts on this?

 

[ptonsparky]

What is the POCO providing to the location? You indicate step up, but from what? 208/120 wye?
Is it too late for the customer to order equipment that matches his existing service?
An 11 amp 480v load is minimal when the requirement for a 480v service may put you customer into a different level of cost from the POCO.

My initial thoughts otherwise would be a 480/277 wye service with step down to 240/120 1 phase for all single phase loads.
RotoPhase and VFDs have their own limitations on how to apply them to equipment that probably has internal control. You will need to educate yourself. It is not Plug & Play.

Welcome to the Forum.

 

[hillbilly1]

Delta 120/240 three phase would probably be the most economical, with such a small 480 volt load, but would be pole mount transformers, as the poco may only offer a Wye 120/208 if pad mount.

 

[ADP]

They have 400A 240/120v 1P service I believe. Possibly 208/120v double checking.

I was thinking an effective and timely configuration (needs to be done this month):

240v 3P delta service.

240v to 480v 9kW xfmr

Current 1P panels, sub them from main.

Would the 1P loads cause any issues for the 3phase service?

 

[ADP]

Sorry, I didn’t simplify total kW.

480v 3p = 9kW
240 3p = 40.5kW
240 1p = 33kW

This includes future growth power.

 

[hillbilly1]

They have 400A 240/120v 1P service I believe. Possibly 208/120v double checking.

I was thinking an effective and timely configuration (needs to be done this month):

240v 3P delta service.

240v to 480v 9kW xfmr

Current 1P panels, sub them from main.

Would the 1P loads cause any issues for the 3phase service?

The poco usually oversizes the single phase pot, with one or two smaller sharing the three phase load. Very common with the high leg delta services having a single phase panel for the receptacle and lighting loads. That’s why they won’t do pad mounts.

 

[ADP]

Is it possible to have a ground coming just from the GEC to the transformer delta 480 secondary side?

Have 208 wye feeding transformer. X0 is floating. 480 delta coming out. 30kVA.
I cannot corner ground delta. Can I just ground casing/ground bar and pull ground from there to 480v panel?
What are my options?

 

[petersonra]

Look at your 480 v loads. Maybe they can be rewired as 240 3 phase. Or the motors changed. Probably cheaper than creating 480 v 3 phase with xfmr and adding 480 v 3 phase panel boards.

 

[synchro]

Is it possible to have a ground coming just from the GEC to the transformer delta 480 secondary side?

Have 208 wye feeding transformer. X0 is floating. 480 delta coming out. 30kVA.
I cannot corner ground delta. Can I just ground casing/ground bar and pull ground from there to 480v panel?
What are my options?

Using a delta-wye in reverse is problematic for multiple reasons. A 208 Delta/480Y like the one at the link below is the way to go if the 480V motors can't be rewired or changed for the lower voltage.

https://store.maddoxtransformer.com...=1&_fid=fe2da9f6f&_ss=c&variant=2102327246857


By the way, three auto-transformers like the one below could get you around 235/136V 3-phase from your 208/120V service. That might be a reasonable compromise for all of your 3-phase and 240V single phase loads.

https://www.automationdirect.com/ad..._buck-boost_transformers_(nema_rated)/t113077

 

[augie47]

With an existing 240v load and adding that small a 480v load you definitely want to keep a 240v service and step-up to 480 for that equipment if it can't be configured for 240.
From your posts, my biggest concern would be that he presently has only a single phase service which, if that is the case, is a whole new ballgame.
You need to confirm if the existing service is single phase or 3 phase and if it is single phase is 3 phase available and at what costs.

 

[petersonra]

Going from a single phase service to 3 phase of any kind is probably going to be kind of pricey. Although I have heard 208/120 can be had many places for about what a single phase service costs.

You need to find someone at the poco to tell you what your options are and what it will cost to get a three phase option. Then you will need to go from there to figure your best option. If the poco will not give you what you think is your best option, you are going to have to deal with what they are willing to give you.

 

[ADP]

Thanks for the info y’all! The service is 208v 3phase. Wye.
I asked tenant if the loads can be turned to 208/240v but I was told only 480v.
I already have the transformer hooked up but not powered up. I’m definitely learning the hard way and won’t make the same mistake again. Now that I have back fed transformer can I pull ground from EGC?
I heard I can get a small wye transformer just to pull the ground from it?

 

[augie47]

It is helpful in these discussions if you reference grounded (normally a neutral) vs equipment grounding as opposed to "ground".

If your equipment does nor require a grounded (neutral) then your 480 delta output may be fine however a lot of modern equipment is not designed to operate on an delta system. You should verify with the equipment manufacturer,.
The transformer wiring should comply with 250.30 as to grounding. {250.30)B)} for ungrounded systems)
also please note 250.21(B) requirement for ungrounded systems.

 

[tortuga]

- 3 fridge containers each @: 480v 3p 3kW.

I recently had a similar problem, customer got "a deal" on some 480V only fridge containers from one of these used container sales places.
She already had them delivered and moved into place by the company, the sales guy was confident there were no 230V models, quick google search proved otherwise.

Cold storage and freezers for sale | Conexwest

www.conexwest.com

Looking at the cost the POCO wanted to upgrade to 480, then step down transformers (after wiating months for them to even get back to me) it was a no brainier to just get rid of the containers and get multi voltage ones that could run on 240V 3 phase

 

[petersonra]

If the xfmr is a sds over 1000 va it requires a gec run to the GES.

 

[petersonra]

I asked tenant if the loads can be turned to 208/240v but I was told only 480v.

How would he know. You might want to do some investigation on your own to see what is really there. I get a lot of really bad info from end users. I trust but verify.

 

[hillbilly1]

I just had a restaurant owner call me all excited about getting some 480 volt three phase equipment cheap. I told him it’s a slight problem, because he has only a 200 amp120/240 single phase service on a wire that is half the size what it’s supposed to be. He quickly canceled the sale! LOL!