Expected life/cost to replace and danger to computer equipment of transformers from 1985

[Wires001]

We have 4 Westinghouse Model 4 DT-3 Type 2 ENCL Class AA Type 150 C Rise Dry Type transformers (catalog CHW75-752-415 Voltage 480A-208Y/120) - one on each floor of our building. They have been here since 1985 when the building was built. They all buzz but one of them got a lot louder for a few days and then went back to its previous volume. This got me wondering if it might be getting ready to fail, and if there could be any damage to computer equipment if it did. An electrical contractor has told us that if one of them failed it could very well fry everything computer related in our building. They quoted us $1200 per transformer to inspect, service and let us know if any of them needs to be replaced. And if one does need tyo be replaced, a cost of $11,000 per transformer total.

I asked several AI engines and all said the chance of damage to computer equipment is low if one of these transformers were to die - but these things are often wrong.

The cost on everything sounds high to me.

Does all of ths sound right?

Any idea what is the expected life on one of these transformers might be?

Thanks much in advance for any help/advice/input offered!

 

[jim dungar]

Transformers from 1985 are not old enough to worry about them failing, unless that have been operating close to their max temperature at full load for 24hrs/day 7days/week 122months/year. Every minute a transformer runs at less than full load in at normal room temperature extends its design life.

Transformers hum as a matter of physics. Increased hum can come from:
rust build up on the core of the transformer, replacement is the only good solution
bolts holding the transformer together may be loose, tightening may be possible
the harmonic content of the load may have changed, nothing can be done
the vibration isolation pads may be becoming brittle, pad replacement is an option


There are other thing that can impact the hum as part of the original installation, but they are not likely to cause an increase and then a decrease as you described.

 

[ptonsparky]

Getting louder to me would make think the load on it changed for some reason.

It won't hurt to have someone open it. Then install some PQ recording for a month or two.

 

[ptonsparky]

Might look for the tin can that sat on it for the duration of the noise.

 

[CoolWill]

Why does the price seem high? How many of these have you installed on the second or third floor of an occupied building?

 

[Wires001]

Thanks much for the replies! Very helpful. What are your thoughts on whether a transformer going out could fry all computers in the building?

 

[petersonra]

Thanks much for the replies! Very helpful. What are your thoughts on whether a transformer going out could fry all computers in the building?

I suppose it might be possible. Just about anything is possible.

 

[CoolWill]

If it fails open, then not likely any damage will occur. If it fails by shorting primary to secondary, then all manner of shenanigans will ensue. They don't often fail that way however. Not by my experience with them anyway.

 

[hillbilly1]

Usually when they start humming louder, it’s the laminations failing, they usually start running hotter too. They still give you enough warning before they fail. I replaced one in a Walmart that was so loud they couldn’t work in the offices across hallway. No voltage problems, but real noisy.

 

[zbang]

One thing I have seen is that a terminal on the low side somehow got loose and was causing abnormal sounds and voltage fluctuations. If that's a concern, de-energize, open the case, and check the terminals. (And $1200 to inspect sounds rather high to me. especially for NC.)

BTW, a very quick check suggests that's a $4000 transformer, and I'd be hard pressed to see how it would be $7000 of labor.

 

[LarryFine]

There is no reason for a humming transformer to affect the loads at all, for humming to predict imminent failure, nor for it failing to cause any more harm than a power loss from other causes.

 

[electrofelon]

I'm in the don't worry about it camp. I think the inspect/service/diagnose is snake oil, like a coolant system flush.

 

[ATSman]

Is it humming Bcuz it doesn't know the words? couldn't resist!
Seriously, if this is IT server equipment fed from these transformers wouldn't it be protected by a UPS if any of them failed?

 

[Wires001]

Is it humming Bcuz it doesn't know the words? couldn't resist!
Seriously, if this is IT server equipment fed from these transformers wouldn't it be protected by a UPS if any of them

 

[Wires001]

@ATSman Servers and switches are all plugged into UPS units but desktop PCs are not. Also It's my underatsning that UPS units provide protection but in the cvent of a major surge like a direct lightning strike, they might not be enough. So if a transformer blew, would the UPS units likely be sufficient?

 

[zbang]

If the building gets a direct strike, all protection bets are off. If the line gets a direct strike, it's hard to say- depends on location of strike, line impedances, quality/size of any surge protection, etc. With a decent SPD and the UPS, you're probably covered for most disturbances.

 

[jim dungar]

So if a transformer blew, would the UPS units likely be sufficient?

Yes.
The failure of a single transformer would cause roughly the same damage as when a storm knocks out the utility.

 

[ATSman]

Yes.
The failure of a single transformer would cause roughly the same damage as when a storm knocks out the utility.

With my experience with utility failures, I not sure if I agree with that statement. Sure both create damaging voltage transients during failure. But due to the physics of a power line vs that of a single 75KVA transformer, I would bet that the utility would win hands down.

 

[LarryFine]

But due to the physics of a power line vs that of a single 75KVA transformer, I would bet that the utility would win hands down.

Which should only serve to allay the OP's concerns.

 

[hbiss]

An electrical contractor has told us that if one of them failed it could very well fry everything computer related in our building. They quoted us $1200 per transformer to inspect, service and let us know if any of them needs to be replaced. And if one does need tyo be replaced, a cost of $11,000 per transformer total.

Probably NOT somebody you would want to do business with.

-Hal