Transformer Y to Y high noise

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DARUSA

Senior Member
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New York City
We are installing a new 500 kva Y to Y transformer 120/208 to 277/480 volts It is a especial setup due to the building have in line Generators. When we energized the transformer it have a so hight noise,like a motor when is stuck. We did check all connection and all appears to be ok.
Building steel ( GEC) equipment bonding jumper correct everything appear to be corret.
What can cause the noise in the transformer ? Thank in advance for your replys.
 
Did you connect a grounded conductor to XO on the 208 volt side ?
(You should not)
 
Personally I wonder who specified a Y-Y? However it's too late now.
Often times some person will specify a Y primary because the supply is a 208Y/120 which is not a good reason.
My reply certainly doesn't solve your problem but I would certainly place the responsibility on that person who decided to go with the Y-Y and let him specify how he wants you to install it.
Otherwise I would not want any liablitity.
 
templdl said:
Personally I wonder who specified a Y-Y? However it's too late now.
Often times some person will specify a Y primary because the supply is a 208Y/120 which is not good reason.
My reply certainly doesn't solve your problem but I would certainly place the responsibility on that person who decided to go with the Y-Y and let him specify how he wants you to install it.
Otherwise I would not want any liablitity.
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The generators are 277/480 volt gas generators and they are on all the time ,it means that they are given power to the system all the time too without transfer switch. The power is going in two directions some time 120/208 is the primary side 277/480 SEC when COGEN generators are off but when generators are on 120/208 is the secondary side and 277/480 PRIM!!!! Is a great system but something happen with the transformer. May be a factory malfunction.
 
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Gone into the engineering phase to me....
all I know is one does not connect the grounded to XO on the primary or your transgormer "sounds liike a stuck motor ":D
 
DARUSA said:
We are installing a new 500 kva Y to Y transformer 120/208 to 277/480 volts It is a especial setup due to the building have in line Generators. When we energized the transformer it have a so hight noise,like a motor when is stuck. We did check all connection and all appears to be ok.
Building steel ( GEC) equipment bonding jumper correct everything appear to be corret.
What can cause the noise in the transformer ? Thank in advance for your replys.
Click to expand...

Lets go step by step.

Low voltage side = 208Y/120 ungrounded?
High voltage side =480Y/277 grounded????

Is there an internal X0-H0 bond?

You energized the LV(?) side with 208V, was the HV side open?

Did you take any current or voltage reading?

Transformers do make noise, electrically they are similar to motors that are 'stuck and not turning'.
 
augie47 said:
Gone into the engineering phase to me....
all I know is one does not connect the grounded to XO on the primary or your transgormer "sounds liike a stuck motor ":D
Click to expand...

Just to make your Saturday informative.:p
Wye-Wye connections have different proscriptions than do Delta-Wyes.

(Y-Y = almost never bond the X0-H0 unless you are acting like a utility; D-Y never ever bond the X0 when running backwards)
 
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jim dungar said:
Lets go step by step.

Low voltage side = 208Y/120 ungrounded?
High voltage side =480Y/277 grounded??

HTML: 
Is there an internal X0-H0 bond?

I don't think so.

HTML: 
You energized the LV(?) side with 208V, was the HV side open?

Yes the secondary OP was open. No load was applied to the transformer.

HTML: 
Did you take any current or voltage reading?

Actually not because I was afraid to the so hight noise that I don't want to step in front of the transformer.
We already install a 750 kva Y to Y before in the same way and no noise was present.
Different manufacturer!!!

Transformers do make noise, electrically they are similar to motors that are 'stuck and not turning'.
Click to expand...
 
DARUSA said:
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How many legs does he transformer have? If it is 3 legs as a common D-Y ro D-D hase that may be the issue.

I omitted to include the second page to my attachement I may have deleted that as part of the file.
 

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I assume you're using a 277/480-120/208 backwards.
So my question is, are you running 3 wires(hot, hot, hot) to the primary? or 4 wires(hot,hot, hot, neutral)?
If you're running 3 wires to the primary then the XO,HO and ground should be bonded together. I had a job where we had magnetic interference with electronics 30-40 feet away. I'm talking about bringing a gauss meter and measure with transformer on and off, and you could see all screens on second floor flickering. And we called siemens and we even talked with their design engineers. It didn't solve it untill we bonded the XO.
If you're running 4 wires, then the XO shouldn't be bonded, but HO and the ground should be bonded together(transformers being a separately derived systems by themself, the HO needs to be stabilized by the ground)
 
templdl said:
How many legs does he transformer have? If it is 3 legs as a common D-Y ro D-D hase that may be the issue.

I omitted to include the second page to my attachement I may have deleted that as part of the file.
Click to expand...

I found the second page.

This may be the answer to your transformer problem.

Take a look at the core design of your transformer as you appear to be questioning it's design.
 

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Strife said:
I assume you're using a 277/480-120/208 backwards.
So my question is, are you running 3 wires(hot, hot, hot) to the primary? or 4 wires(hot,hot, hot, neutral)?
If you're running 3 wires to the primary then the XO,HO and ground should be bonded together. I had a job where we had magnetic interference with electronics 30-40 feet away. I'm talking about bringing a gauss meter and measure with transformer on and off, and you could see all screens on second floor flickering. And we called siemens and we even talked with their design engineers. It didn't solve it untill we bonded the XO.
If you're running 4 wires, then the XO shouldn't be bonded, but HO and the ground should be bonded together(transformers being a separately derived systems by themself, the HO needs to be stabilized by the ground)
Click to expand...
120/208 is in teory the primary side 277/480 is the secondary side but it change on the way!!!
 
DARUSA said:
No D to D or D to Y it is Y to Y transformer.
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As I said a 3 legged core transformer is commonly used for D-D or D-Y transformers. As such someone who is not familiar with a Y-Y transformer and has seen a common d-y that has a 3 legged core should find that the Y-Y transformer of the OP KVA size will have a core with at least on more leg which I may not have made myself clear in my previous post. As such simply opening the enclosure and looking at the core and coil construction should be an indicator of the that the transformer was designed as a Y-Y. You could be chasing your tail by trying to discover why the transformer was reacting the way that it is. If you can eliminate a transformer design problem then you can continue to direct your attention in other areas.
When engineering small Y-Y transformers it is acceptable to use 3-legged cores with the addition of a tertiary winding which deals with the ferroresonance that is inherent in a Y-Y wound transformer. It provides a closed-circuit path for zero-sequence currents/fluxes. That is most typically the case with transformers that, for system reasons, must be connected wye-wye (star-star for those in the IEC world). With a wye-wye transformer, the only path for zero-sequence flux is the tank of a transformer (and if the three-phase bank is comprised of three single-phase units, even that does not exist). The tank is a high-impedance path, so the result is that the zero sequence impedance seen looking into the transformer is very high. Also, the circulation of zero sequence current through the tank will cause the tank to heat and lead to paint failure. A tertiary winding presents a low impedance path to zero sequence currents, thereby reducing the zero sequence impedance presented to the outside world, while avoiding the problem of tank heating.

I worked for a transformer manufacturer as a soles engineer an there have been imes that my engineers just weren't thinking, my assemblers weren't thinking, and a whole host of other factors came together to produce a product that got out the door incorrectly made.
 
templdl said:
As I said a 3 legged core transformer is commonly used for D-D or D-Y transformers. As such someone who is not familiar with a Y-Y transformer and has seen a common d-y that has a 3 legged core should find that the Y-Y transformer of the OP KVA size will have a core with at least on more leg which I may not have made myself clear in my previous post. As such simply opening the enclosure and looking at the core and coil construction should be an indicator of the that the transformer was designed as a Y-Y. You could be chasing your tail by trying to discover why the transformer was reacting the way that it is. If you can eliminate a transformer design problem then you can continue to direct your attention in other areas.
When engineering small Y-Y transformers it is acceptable to use 3-legged cores with the addition of a tertiary winding which deals with the ferroresonance that is inherent in a Y-Y wound transformer. It provides a closed-circuit path for zero-sequence currents/fluxes. That is most typically the case with transformers that, for system reasons, must be connected wye-wye (star-star for those in the IEC world). With a wye-wye transformer, the only path for zero-sequence flux is the tank of a transformer (and if the three-phase bank is comprised of three single-phase units, even that does not exist). The tank is a high-impedance path, so the result is that the zero sequence impedance seen looking into the transformer is very high. Also, the circulation of zero sequence current through the tank will cause the tank to heat and lead to paint failure. A tertiary winding presents a low impedance path to zero sequence currents, thereby reducing the zero sequence impedance presented to the outside world, while avoiding the problem of tank heating.

I worked for a transformer manufacturer as a soles engineer an there have been imes that my engineers just weren't thinking, my assemblers weren't thinking, and a whole host of other factors came together to produce a product that got out the door incorrectly made.
Click to expand...

The last line is just being human.

Does the same 4 leg configuration help eliminate the Harmonics issue in older buildings that have had a lot of upgrades to newer equipment (like electronic balasts and computors) ?
 
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