CLICK HERE AND JOIN OUR COMMUNITY TODAY, IT'S FREE!
Go Back   Electrician Talk - Professional Electrical Contractors Forum > Electrical Trade Topics > Services and Service Equipment

Reply
 
Thread Tools Search this Thread Display Modes
Old 03-07-2009, 01:09 PM   #1
Always Learnin'
 
Join Date: Sep 2007
Location: Indiana
Posts: 1,294
Rewards Points: 500
Default 480V Delta vs 480V Y

I have a situation with some new machinery coming to a factory. The engineers say the equipment needs 480V Y but it doesn't need a neutral. Presently the plant only has a 1200A 120/240 3Ø delta service. We were going to set a 112.5kva 240V delta primary/480V Y secondary transformer to take care of this new equipment. The trouble is finding a 480V Y secondary tranny. Everything is 480V Delta. Most transformers above 1 kva are listed to be wired in reverse so we have looked at that too. No luck finding a 480V Y primary/240V Delta secondary. My question is, if the equipment doesn't require a neutral how would it discern 480 Y from 480 Delta? I thought I saw a thread dealing with this a few days ago but I can't sem to find it. Can anyone shed some light on this? Thanks.

amptech is offline   Reply With Quote
Join Contractor Talk

Join the #1 Electrician Forum Today - It's Totally Free!

ElectricianTalk.com - Are you a Professional Electrical Contractor? If so we invite you to join our community and see what it has to offer. Our site is specifically designed for you and it's the leading place for electricians to meet online. No homeowners asking DIY questions. Just fellow tradesmen who enjoy talking about their business, their trade, and anything else that comes up. No matter what your specialty is you'll find that ElectricianTalk.com is a great community to join. Best of all it's totally free!

Join ElectricianTalk.com - Click Here JOIN FOR FREE


Warning: The topics covered on this site include activities in which there exists the potential for serious injury or death. ElectricianTalk.com DOES NOT guarantee the accuracy or completeness of any information contained on this site. Always use proper safety precaution and reference reliable outside sources before attempting any construction or remodeling task!

Old 03-07-2009, 01:49 PM   #2
Registered Member
 
Join Date: Feb 2008
Location: Atlanta, Ga/Hamilton, Al
Posts: 4,868
Rewards Points: 2,000
Default

You will just have to tap the secondary that way. If you are using a transformer that comes from the factory with a 480 V delta primary and a 120/208 V Y secondary, backwards, then you need to retap it to what you need.

P.S. And the equipment will not be able to tell whether it is getting delta or Y connected 480. But the Y would be required for equipment grounding purposes. Without it, there would be no place to ground the frame.


Last edited by InPhase277; 03-07-2009 at 02:12 PM.
InPhase277 is offline   Reply With Quote
Old 03-07-2009, 03:51 PM   #3
Modérateur
 
frenchelectrican's Avatar
 
Join Date: Mar 2007
Location: NE Wi / Paris France{ In France for while }
Posts: 4,836
Rewards Points: 2,000
Default

Most case you can able get the transfomer run in reverse however there is a item or two you need to be address here .,

You will need to adjust the tap after you power up to get the correct voltage rating.

as far for grounding make sure you bond it properly otherwise you may get unstable voltage if not taken care of it.

Merci,Marc
__________________
Bleu est beau.
frenchelectrican is offline   Reply With Quote
Old 03-07-2009, 05:25 PM   #4
Bilge Rat
 
Join Date: Aug 2007
Location: Fernley, Nevada (near Reno)
Posts: 3,489
Rewards Points: 2,122
Default

Quite likely the requirement for the 480 wye connection has to do with the MOVs used in VFDs. If this is true, and the equipment is connected to a 480 delta system, the MOVs will likely blow up, whether the delta is floating or grounded B.

If a delta system is installed, it can be easily made into a wye by means of a grounding transformer. You can make your own from 3 small (100VA is plenty) single phase transformers with 480 volt primaries, and any secondary voltage. Just connect the primaries in a wye, and ground the center of the wye. Make sure the 480 delta transformer is not grounded on the 480 side. This set-up will create a grounded wye, but the load must be 3 phase 3 wire, no neutral.

If you want to go a step further, you can easily make a ground fault detector from this set-up. Simply connect the secondaries of the single phase transformers in a delta, and leave one corner open. Connect a relay coil across the open corner. Connect the contact of the relay to trip the feeder breaker.

Here's how it works; Say the single phase transformers are 480 primary, and 120 secondary. Under normal conditions very little voltage will appear across the open corner (and the relay coil). If one of the 480 volt power legs becomes grounded, 120 volts will appear across the open corner. This will energize the relay coil, and trip the feeder breaker.

I've done several of these where an existing drive isolation transformer was delta-delta, and the new drive needed a wye connection.

Rob

Last edited by micromind; 03-07-2009 at 05:30 PM.
micromind is offline   Reply With Quote
Old 03-07-2009, 05:34 PM   #5
Wire Ninja
 
MDShunk's Avatar
 
Join Date: Jan 2007
Location: Beautiful Cumberland Valley, in PA
Posts: 17,322
Rewards Points: 2,034
Default

The last time I bumped into this (printing presses), my choices were to have one wound and wait 6 weeks, buy a tested used transformer that had a 480 wye secondary (Romac) or buy three single phase transformers and make up my own bank. I bought used.
__________________
One reason not to give DIY advice:
Catch a man a fish and you can sell it to him.
Teach a man to fish and you’ve ruined a good business opportunity.
MDShunk is offline   Reply With Quote
Old 03-07-2009, 11:40 PM   #6
Patriot1
 
Join Date: Feb 2009
Location: doltan, ala
Posts: 56
Rewards Points: 75
Default

I posted this in "watch for the high leg" thread, maybe this is what you saw....

"
I believe that the high leg panel should be for equipment use only, ie..a/c, motor, lighting, xfmrs...etc..strickly 3 phase or 1 phase items that would not "see" the "wild", "freak", "high" leg until it went to ground. There is a local church that has 120/208 and connected 3 single phase xfmrs so they could have a high leg to operate their a/c's more economically."
patriot1 is offline   Reply With Quote
Old 03-08-2009, 12:42 AM   #7
DGFVT
 
Join Date: Jan 2007
Location: VT
Posts: 2,449
Rewards Points: 1,000
Default

Quote:
Originally Posted by amptech View Post
I have a situation with some new machinery coming to a factory. The engineers say the equipment needs 480V Y but it doesn't need a neutral. Presently the plant only has a 1200A 120/240 3Ø delta service. We were going to set a 112.5kva 240V delta primary/480V Y secondary transformer to take care of this new equipment. The trouble is finding a 480V Y secondary tranny. Everything is 480V Delta. Most transformers above 1 kva are listed to be wired in reverse so we have looked at that too. No luck finding a 480V Y primary/240V Delta secondary. My question is, if the equipment doesn't require a neutral how would it discern 480 Y from 480 Delta? I thought I saw a thread dealing with this a few days ago but I can't sem to find it. Can anyone shed some light on this? Thanks.
Will this work?

Attachment 1094

Last edited by John; 07-18-2009 at 07:35 AM.
John is offline   Reply With Quote
Old 07-25-2009, 03:52 PM   #8
Junior Member
 
Join Date: Jul 2009
Location: canada
Posts: 19
Rewards Points: 10
Default

Is the equitment from the Eu.
If it is the ground is used as neutral!
j johnson is offline   Reply With Quote
Old 07-29-2010, 12:47 AM   #9
Junior Member
 
Join Date: Jul 2010
Location: texas
Posts: 1
Rewards Points: 10
Default

My line voltage is unvalance every so often to ground. for example. We take a reading between ground and line voltage and L1 to ground is 120, L2 to ground is 380 and L3 to ground 500 volts. but then it goes normal. 277 to ground. my secondary is Y connection.
Ernesto J Delgadillo is offline   Reply With Quote
Old 07-29-2010, 12:58 AM   #10
Senior Member
 
Join Date: Jul 2010
Location: LA, CA
Posts: 183
Rewards Points: 150
Default

[quote=amptech;63437]I have a situation with some new machinery coming to a factory. The engineers say the equipment needs 480V Y but it doesn't need a neutral. Presently the plant only has a 1200A 120/240 3Ø delta service. We were going to set a 112.5kva 240V delta primary/480V Y secondary transformer to take care of this new equipment. The trouble is finding a 480V Y secondary tranny. Everything is 480V Delta. Most transformers above 1 kva are listed to be wired in reverse so we have looked at that too. No luck finding a 480V Y primary/240V Delta secondary. My question is, if the equipment doesn't require a neutral how would it discern 480 Y from 480 Delta? I thought I saw a thread dealing with this a few days ago but I can't sem to find it. Can anyone shed some light on this? Thanks.[/quote

Last edited by Nildogg; 07-30-2010 at 07:16 PM.
Nildogg is offline   Reply With Quote
Old 07-29-2010, 12:28 PM   #11
Senior Member
 
reddog552's Avatar
 
Join Date: Oct 2007
Location: Mundys Corner Pa Now IN Belleville Il.
Posts: 151
Rewards Points: 81
Default

. And the equipment will not be able to tell whether it is getting delta or Y connected 480. But the Y would be required for equipment grounding purposes. Without it, there would be no place to ground the frame.[/quote]
I DISSAGREE WITH THIS u can have a EGC on a Delta secondary.
reddog552 is offline   Reply With Quote
Old 07-29-2010, 04:37 PM   #12
Junior Member
 
Join Date: Jul 2010
Location: Telford, Pa
Posts: 2
Rewards Points: 10
Default

The best way to create 480 volt Y would be to use the primary of the incoming service and install the appropriate transformer.
If that is not possible use (3)-single phase 37 kva transformers 277 volt primary / 120-240 volt secondary.
Of course the 277 volt will be used as the secondary connected is Y configuation. The 240 volt will be used as the primary connected in a delta configuration.
Such as a Hammond cat. # MF37037FE.

Bill
BILLY 101 is offline   Reply With Quote
Old 07-29-2010, 05:45 PM   #13
Senior Member
 
Skipp's Avatar
 
Join Date: May 2010
Location: Orange County, CA.
Posts: 363
Rewards Points: 250
Default

This thread is a year old. I'm sure the OP has figured it out by now.

Skipp is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
277V/480V vs 347V/600V Jeff000 General Electrical Discussion 43 08-10-2013 09:25 PM
480v Retrofit bulbs? Caesar General Electrical Discussion 6 02-17-2010 11:56 AM
480v welding recept's. NorthDakota_PM General Electrical Discussion 5 09-09-2008 06:57 PM
480V-240V transformer kurt.brinker General Electrical Discussion 5 02-26-2008 03:07 AM
480V needed i-automate General Electrical Discussion 6 08-14-2007 11:04 AM


All times are GMT -4. The time now is 08:14 PM.


Copyright © 2006-2014 Escalate Media LP. All Rights Reserved
Our Pro Sites Network
ContractorTalk.com | DrywallTalk.com | HVACSite.com | PaintTalk.com | PlumbingZone.com | RoofingTalk.com