TRANSFORMER BACKUP

[puckman]

I have a task of backing up a transformer 30 or 45 kva that supplies 120 volt control power , meters , electric valves ,plc's , lighting and such. Should there be a loss of this transformer for a short amount of time this would be very damaging and expensive to the company.

One way I was thinking about was to add a transformer wired up but lockout until needed. On the output side of the existing transformer [208/120] I would install a transfer switch before the existing 208/120 loadcenter that would remove the output from the existing transformer and put the replacement transformer output to the loadcenter. The switching will be done with both primary power deenergized.

If someone has another way or see something wrong with this installation please post . I am looking for better and complient methods for this job.
Thanks for the help.

 

[masterinbama]

I don't see why a manual transfer switch on the secondary wouldn't work. How about the primary side, or do you have enough breakers in your 480 gear to not need a transfer switch on the primary too.

 

[puckman]

I would have to use a transfer switch on the secondary side to isolate the transformers output. I believe i can feed each trans with a seperate breaker in same panel. We will be looking over the job today and try and get some options. thanks forthe help.

 

[kwired]

How short of a time is acceptable to be down? If not acceptable at all you need UPS.

You are more likely to lose utility power more often than you will ever lose the transformer.

 

[maghazadeh]

How short of a time is acceptable to be down? If not acceptable at all you need UPS.

You are more likely to lose utility power more often than you will ever lose the transformer.

Well said.:thumbsup:

 

[texie]

How short of a time is acceptable to be down? If not acceptable at all you need UPS.

You are more likely to lose utility power more often than you will ever lose the transformer.

I would agree. This seems to be an expensive modification for very little additional reliability/redundancy. In my mind there are a whole lot of things in the chain that will likely fail before the xformer.

 

[Marvin_Hamon]

I think you might want to be backing up the control power supply and not the transformer. For a backup control power supply you need an alternate source of power. What you need depends on how long you need to supply the backup power, how fast you need the backup to come online, and what your utility service is like. You are probably going to need to look at an inline UPS or a combination inline UPS and backup generator.

 

[puckman]

I understand the possiablity is low that a transformer goes down but it.................big concerns, multible electric valves, lighting etc.
We have a backup generator for the plant but that does not help when we need 120 volts to open and close air lines , valves.
All controllers would be down . We have battery power for the plc but that is not enough.. I am not sure there is anyone that knows what the time period will be ,lets say 30 minutes .
There is 9-10 circuits comming to this control panel that will have to stay energized quickly . More work will be needed to look into sizing a ups. Good idea. thank you.

 

[Cow]

Don't transformers often last 30-50 years?

Do you think a spare transformer sitting on the floor unused for 30 years would work when you finally threw the switch to it? What about all the grease hardening up in a transfer switch that never gets used?

Or the flipside, you rotate between transformers every couple mos. or so just to keep things excersized. But then they complain because now you have to regularly cut their critical power, even if only for a moment when your flipping the transfer switch.

Seems like a big waste of time/money for almost zero benefit.

 

[gk351]

I would look into putting the secondary on a Genset with an ATS. It could provide a lower cost option than backing up the primary side. Having a back up xfmr might look good on paper, but something I have never seen.

 

[puckman]

The idea is to use the trans on the secondary side. So if cost was a factor a generator and ats is a much higher cost than a trans and mts.
A ups might be the best idea yet and i appriciate everyone ideas here this is why i come here and ask you expieranced guys for your help.

This trans has been in service since 1980's and should it go down it could be in the hundreds of thousands $$$$ . All depands on when it happens.
The lost of equipment due to down time to repairs for one ,off line for two , cleanup and so on. Damage could be high so for the cost of a trans and a mts is not much when you look at all involved here.
Thanks to everyone for their ideas . This site has the most expierenced guys who always seem to comeup with the answers to all the problems.

 

[kwired]

The idea is to use the trans on the secondary side. So if cost was a factor a generator and ats is a much higher cost than a trans and mts.
A ups might be the best idea yet and i appriciate everyone ideas here this is why i come here and ask you expieranced guys for your help.

This trans has been in service since 1980's and should it go down it could be in the hundreds of thousands $$$$ . All depands on when it happens.
The lost of equipment due to down time to repairs for one ,off line for two , cleanup and so on. Damage could be high so for the cost of a trans and a mts is not much when you look at all involved here.
Thanks to everyone for their ideas . This site has the most expierenced guys who always seem to comeup with the answers to all the problems.

What is cost of the transformer? If it goes down it will need replaced anyway. Sounds like it has enough age that it may be justified to plan to retire it anyway. If it is that critical maybe there should be some periodic insulation testing done on it, new or old.