# Transformers



## jza (Oct 31, 2009)

:wallbash:

http://www.schneider-electric.us/si...&country=US&lang=EN&id=FA101694&redirect=true










But is this really a three phase transformer? With an output of 240?


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## cdnelectrician (Mar 14, 2008)

Magnettica said:


> I have an existing 45KVA 480/ 240 Wye transformer supplying a 45kW water heater. Is the transformer undersized for this load? Been forever since I did any transformer/ commercial 3-phase wiring and I'm just not certain. The wiring looks a little hack-ish (conductors aren't identified, lack of insulated bushings, etc).


That is a big water heater!


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## Magnettica (Jan 23, 2007)

Yes it is! Not sure why they didn't connect the NG but here it is.


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## MTW (Aug 28, 2013)

Magnettica said:


> Coming from a failed businessman.... whatever douche.


I'm happy to be a failed business man but at least I'm an electrician. :thumbsup:


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## Magnettica (Jan 23, 2007)

MTW said:


> I'm happy to be a failed business man but at least I'm an electrician. :thumbsup:


.........


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## MTW (Aug 28, 2013)

Magnettica said:


> You're also a loser.


I can live with that. Any thing else you'd like to add?


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## Magnettica (Jan 23, 2007)

See this negative spiral path you've created by insulating my intelligence as an electrician? 

This does nothing but harm to your reputation in the real world.


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## Rollie73 (Sep 19, 2010)

MTW said:


> I'm happy to be a failed business man but at least I'm an electrician.


Since you're such an awesome electrician.....why don't you try doing some calculations and helping the guy out instead of trolling.




Mag.......Are you sure it is 45,000 watt water heater @ 240 volts? That's somewhere around 187 amps. Sounds large. 
It seems to me that it is likely a 4.5Kw or 4500 watts which would be a draw of 18.7 amps....but you are the guy on site who has actually seen it.


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## Magnettica (Jan 23, 2007)

I got a call today and was told they smelled something funny coming from the transformer so they turned the disconnect off. None of the conductors were properly identified and were missing some plastic bushings. I suspect things weren't right here. This area is not area of specialty. Maybe Peter D can help me I thought so I posted here.


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## Rollie73 (Sep 19, 2010)

Yeah....that transformer will JUST handle that as long as there is no other connected load. That tank draws 108 amps when wired up as 3 phase unit and the transformer will do 108 amps. 

Connect a few 100 watt bulbs and you're overloading the transformer.


FWIW......I would prefer to see a 75KvA transformer in that situation


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## MTW (Aug 28, 2013)

Is it connected single phase or three phase?


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## Rollie73 (Sep 19, 2010)

MTW said:


> Is it connected single phase or three phase?


Wow.....a helpful question.:laughing:

If its connected single phase it will WAY overload that transformer. Are you guys required by the NEC to fuse the secondaries of transformers?


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## MTW (Aug 28, 2013)

Rollie73 said:


> Wow.....a helpful question.:laughing:
> 
> If its connected single phase it will WAY overload that transformer.


Wow, I didn't know that.


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## Rollie73 (Sep 19, 2010)

MTW said:


> Wow, I didn't know that.


Yes well........I figured such an _awesome_ electrician wouldn't have to ask such an _obvious_ question. 


I noticed how you edited out my question. Guess you can't answer that one either huh?


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## Next72969 (Dec 9, 2012)

Rollie73 said:


> Yes well........I figured such a handsome electrician wouldn't have to ask such an obvious question.  I noticed how you edited out my question. Guess you can't answer that one either huh?


 fify


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## Magnettica (Jan 23, 2007)

So the transformer's at it's maximum output. Is that right?


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## Magnettica (Jan 23, 2007)

From my recollection.... 


45,000/ 415 (240x 1.732) = 108.4 amps, which is exactly what I was reading on the amprobe.


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## MTW (Aug 28, 2013)

Rollie73 said:


> Yes well........I figured such an _awesome_ electrician wouldn't have to ask such an _obvious_ question.
> 
> 
> I noticed how you edited out my question. Guess you can't answer that one either huh?


It depends. Under certain circumstances, yes.


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## Aegis (Mar 18, 2011)

If this transformer is in ruff shape then you may not want to load it to the max. 

But it's up to you


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## MTW (Aug 28, 2013)

Magnettica said:


> I have an existing 45KVA 480/ 240 Wye transformer supplying a 45kW water heater.


There's no such thing as a wye transformer in that voltage configuration. Do you have a pic of the transformer label in question?


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## Magnettica (Jan 23, 2007)

Aegis said:


> If this transformer is in ruff shape then you may not want to load it to the max.
> 
> But it's up to you


It's less than a year old. 

I asked the maintenance guy which electrician installed it and he said he couldn't find the invoice. I thought that was a bit strange. The building itself is a church/ learning center in Rahway here and is less than 12 years old.


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## ponyboy (Nov 18, 2012)

Magnettica said:


> From my recollection.... 45,000/ 415 (240x 1.732) = 108.4 amps, which is exactly what I was reading on the amprobe.


 Yeah but you're probably feeding it with 208v 3 phase correct?
I think you should be closer to 125.


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## MTW (Aug 28, 2013)

Why would they choose a 240 volt water heater with 480 volts available?


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## ponyboy (Nov 18, 2012)

MTW said:


> Why would they choose a 240 volt water heater with 480 volts available?


 The resistance is fixed. Voltage goes up current goes up. I think


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## ponyboy (Nov 18, 2012)

ponyboy said:


> Yeah but you're probably feeding it with 208v 3 phase correct? I think you should be closer to 125.


I wanna see this transformer before making any more assumptions. Did you get a pic of it?


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## MTW (Aug 28, 2013)

ponyboy said:


> The resistance is fixed. Voltage goes up current goes up. I think


Yeah but that water heater is rated 240 volts. Apply 480 to it and it will last a few seconds.


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## ponyboy (Nov 18, 2012)

MTW said:


> Yeah but that water heater is rated 240 volts. Apply 480 to it and it will last a few seconds.


Indeed. I wanna see this pig


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## micromind (Aug 11, 2007)

A 45 KVA transformer will operate a 45 KW water heater all day long without issue provided that......

1) The ambient temperature where the transformer is located is less that 104ºF and there's no airflow restriction around it. Including it being mounted too close to walls. 

2) The low side voltage does not exceed 240 under load. If it does, then the current will be above the rating of the transformer. 

If I were installing this system, I would change the taps on the high side a step or two above 480. This way the low side voltage will be below 240 and the current will be well within the rating. 

Of course, this will result in the 45 KW heater being actually 44 or 43, but I seriously doubt it'd matter.


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## Magnettica (Jan 23, 2007)

ponyboy said:


> Yeah but you're probably feeding it with 208v 3 phase correct?
> I think you should be closer to 125.


Primary is 480, 3 phase.


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## Magnettica (Jan 23, 2007)

X1 - x2 = 246
x2 - x3 = 247
x1 - x3 = 246


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## Aegis (Mar 18, 2011)

Post pics of the tranny!



...sorry wrong thread.


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## Magnettica (Jan 23, 2007)

I'll have pics tomorrow afternoon. Thanks for the help guys.


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## ponyboy (Nov 18, 2012)

Magnettica said:


> Primary is 480, 3 phase.


I meant feeding the water heater. I'd assume your transformer secondary is 208 phase to phase if it's a standard delta-Y. But you said its 240 so I'm curious as to what you got now


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## micromind (Aug 11, 2007)

ponyboy said:


> I meant feeding the water heater. I'd assume your transformer secondary is 208 phase to phase if it's a standard delta-Y. But you said its 240 so I'm curious as to what you got now


The transformer in question is most likely 480∆ on the high side and 240∆ on the low side. It might have a center tap to get 120, maybe not though.

It could be 138/240Y on the low side, but these are not very common.


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## Rollie73 (Sep 19, 2010)

micromind said:


> A 45 KVA transformer will operate a 45 KW water heater all day long without issue.


The available power is there as long as nothing else is connected to that tranny. 
I notice there are 9 heater elements in the water heater....I wonder if they all come on at once or just as they are required. Maybe they only noticed the smell from the transformer because all the elements were actually working. 
Just thinking out loud here


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## Magnettica (Jan 23, 2007)

It is a Delta/ Delta. 

My bad.


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## Magnettica (Jan 23, 2007)

Here's a shot I took today.


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## Rollie73 (Sep 19, 2010)

The info still doesn't change. It still puts out 108 amps so it will run the water heater but it is maxed out for it.......IF , all of the elements are on at the same time and the tank is using the full 45kW.


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## Maple_Syrup25 (Nov 20, 2012)

put a fan behind the transformer. OR go bigger and give the system some breathing room.


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## ghostwriter (Nov 1, 2007)

*Transformer*

Just make sure you ground the secondary properly and identify your new voltage system as per 210.

I wouldn't be surprised if some of the issues are because the secondary is not grounded properly.


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## micromind (Aug 11, 2007)

Even though it's not overloaded, if it were me, I'd change the taps to tap 2. This will lower the secondary voltage a bit and thus lower the current.


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