Transformer replacement

[Shockedby277v]

Hey guys,

I recently visited a facility that is 9 years old and basically a cookie cutter of the building I am doing. They have 2 4000 amp services . They have a 3rd transformer pad to keep a spare transformer on-site. They had to swap out transformers on 2 separate times. The electrical installations weren't up to par. Now for my questions. Can the installations have part to do with this?? What would cause this?? What to do to avoid this???

Thanks in advance

 

[sgunsel]

You are not providing much information for a diagnosis.
What was installed?
What was "not up to par"
What was the failure mode?

 

[Shockedby277v]

I guess I'm looking for common reasons why a utility transformer would fail to the point they would need to keep a spare on-site. And as far as the electrical installations, there wasn't much I was impressed with. i.e sealtite in a class 1 div 1 area ... not seeing every installation and only assuming it could be part of the problem....

 

[kwired]

How about transformer undersized for the load it supplies? POCO's in general will undersize them to some degree.

Excessive harmonic loads?

Power factor issues?

Load unbalanced across phases?

 

[zog]

I guess I'm looking for common reasons why a utility transformer would fail to the point they would need to keep a spare on-site. And as far as the electrical installations, there wasn't much I was impressed with. i.e sealtite in a class 1 div 1 area ... not seeing every installation and only assuming it could be part of the problem....

Define "fail", what was wrong with them? No one just swaps out transformers, who said they failed and what was the basis of that decision?

 

[brian john]

Sub par, recently went to a site that had a transformer that had an oil leak. I expressed my concerns, and the on site electrician said it was not an issue. I tried to convince the customer and was told I was just trying to drum up work.

I walked and I hope it blows at Christmas when this agency moves a boat load of mail.

Sub par fans not working?
Sub par lots of secondary faults
Sub par, leaks into the enclosure of a dry type transformer.
Sub par, loose termination's in the transformer

And the list goes on and on.

 

[eric9822]

Details would be very helpful as others have suggested. Keeping a spare transformer on hand does not necessarily indicate a poor installation. Lots of businesses have contingency plans that include keeping high dollar spares with a very low chance of use. I have over $200K in spare transformers on hand that I hope I will never need. What is the issue?

 

[T.M.Haja Sahib]

Details would be very helpful as others have suggested. Keeping a spare transformer on hand does not necessarily indicate a poor installation. Lots of businesses have contingency plans that include keeping high dollar spares with a very low chance of use. I have over $200K in spare transformers on hand that I hope I will never need. What is the issue?

The spare transformers need to be kept energized adding to the energy cost.

 

[Volta]

The spare transformers need to be kept energized adding to the energy cost.

Why?

 

[Volta]

I guess I'm looking for common reasons why a utility transformer would fail to the point they would need to keep a spare on-site. And as far as the electrical installations, there wasn't much I was impressed with. i.e sealtite in a class 1 div 1 area ... not seeing every installation and only assuming it could be part of the problem....

Is it truly POCO at that point? Might the customer own the transformers and the service disconnect is HV?

 

[kwired]

The spare transformers need to be kept energized adding to the energy cost.

Why?

So they can all fail at same time when some event on the line takes out the one in use, oops.:slaphead:

 

[Volta]

So they can all fail at same time when some event on the line takes out the one in use, oops.:slaphead:

I guess that's one way to learn!

 

[T.M.Haja Sahib]

I guess that's one way to learn!

Surely you must be joking Volta & Kwired. Because What I said is an industrial practice to avoid condensation in the transformer.

 

[Besoeker]

Surely you must be joking Volta & Kwired. Because What I said is an industrial practice to avoid condensation in the transformer.

Not one that I have seen implemented. If it's a dry type, wrap it up keep it in a dry place. If it's ONAN, you'd test the oil regularly or at least before you put it into service.
We have a lot of equipment, mainly variable speed drives, that have unit transformers. When the drive is off, the transformer is de-energised. In one particular case, the drives are standby for gas turbine driven compressors. The drives are put into service for a few weeks a year while the turbines are being overhauled. The rest of the time the drives are off and the transformers are not on line.

Back to the OP.
One reason for having spare transformers on site is because of the long lead time to procure a replacement.

 

[T.M.Haja Sahib]

Not one that I have seen implemented. If it's a dry type, wrap it up keep it in a dry place. If it's ONAN, you'd test the oil regularly or at least before you put it into service.
We have a lot of equipment, mainly variable speed drives, that have unit transformers. When the drive is off, the transformer is de-energised. In one particular case, the drives are standby for gas turbine driven compressors. The drives are put into service for a few weeks a year while the turbines are being overhauled. The rest of the time the drives are off and the transformers are not on line.

Back to the OP.
One reason for having spare transformers on site is because of the long lead time to procure a replacement.

In T.M.Tagare's well known book 'Reactive Power Management' published by Tata Mc Graw Hill,the statement that it is an industrial practice to keep standby transformer energized is present.

Back to the OP.
One reason for having spare transformers on site is because of the long lead time to procure a replacement.

In India,the power companies are sometimes willing to replace the faulty transformer of the consumer quickly with their own on a chargeable basis.Is such a practice not available in US?

 

[Volta]

In T.M.Tagare's well known book 'Reactive Power Management' published by Tata Mc Graw Hill,the statement that it is an industrial practice to keep standby transformer energized is present....

Well, I guess you either shouldn't believe everything you read, or look should closely at the difference between 'standby' and 'spare'.

 

[T.M.Haja Sahib]

Well, I guess you either shouldn't believe everything you read, or look should closely at the difference between 'standby' and 'spare'.

Tata McGraw Hill is a reliable source of Publishers.You can trust.
In the context of this thread,the distinction between 'standby' and 'spare' does not matter.

 

[Besoeker]

In T.M.Tagare's well known book 'Reactive Power Management' published by Tata Mc Graw Hill,the statement that it is an industrial practice to keep standby transformer energized is present.

I go to a lot of different industrial plants. I haven't come across that practice in any of them. And Volta makes a good point about differentiating between spare and standby.

In India,the power companies are sometimes willing to replace the faulty transformer of the consumer quickly with their own on a chargeable basis.Is such a practice not available in US?

I don't know if is. I'm not from there.
Most of the power transformers we use are non-standard. (I mean we as a company, not the UK as a whole.)
It would be unlikely to find a replacement for a non-standard unit unless the customer keeps a spare. Some do.

 

[T.M.Haja Sahib]

I go to a lot of different industrial plants. I haven't come across that practice in any of them. And Volta makes a good point about differentiating between spare and standby.





I don't know if is. I'm not from there.
Most of the power transformers we use are non-standard. (I mean we as a company, not the UK as a whole.)
It would be unlikely to find a replacement for a non-standard unit unless the customer keeps a spare. Some do.

Please read 3.10 in
http://www.sirfrt.com.au/wikis/imrt/images/8/81/HVOP-FOURTH-EDITION-MAROON-BOOK.pdf
or first point under Electrical Systems in
http://pcra.org/English/general/tipstextile.htm
What is your stand now?

 

[Besoeker]

Please read 3.10 in
http://www.sirfrt.com.au/wikis/imrt/images/8/81/HVOP-FOURTH-EDITION-MAROON-BOOK.pdf
or first point under Electrical Systems in
http://pcra.org/English/general/tipstextile.htm
What is your stand now?

I wasn't taking a stand on it. I was simply telling you what I have seen on the many different industrial sites (including Water and Petrochem) that I've visited.

Your two inks are diametrically opposed. Sydney Water wants the standby transformer and cables to remain energised where practicable.
From the PCRA we have "Stand by transformers should be de-energized to conserve energy wherever possible except for monsoon period to avoid the possibility of moisture contamination."

Two different spellings of "energised" - two different versions of English.