How long do transformers last
 

I wired a buck boost transformer to go from 208V to 230V for the air compressor. Has worked perfectly for 5 years. Stopped working the other day. Have compressor in the 208 outlet now.

Do they have a fixed life? Is 5 years of constant use (most days compressor runs to fill up at least 30 times) considered normal?

Are they hour rated, or cycle rated??

I will have to look at the documentation this weekend.

Sized correctly they last forever, well close. Was it large enough for the starting load? Is your motor failing and drawing more amperage?

Depends on the transformer, I guess. I have an old "transformer powered" desk lamp I bought in the early 60's 110 to 12v, uses a #1156 automotive tail light bulb.

It's lighting my keyboard as I type...

Look closely because most transformers are more than meets the eye.

Good questions. I will dig up the specs tomorrow but IIRC correctly, I asked the vendor if it would work given my compressor, sent them this link and they said yes.

DeWalt 5-HP 80-Gallon Two-Stage Air Compressor (230V 1-Phase)

Environmental conditions matter too.
Transformers give off heat and can get dirty.
How hot did it get?
Where was it located?

How did it fail? Shorted? No continuity on primary or secondary side?

I only know about guitar amp transformers, but they pretty much last forever if treated properly. That means the impedance or load has to always be correct. A tube shorting out can kill it. As long as it's running properly, it should not be putting out much heat, which means it could be covered in dirt, dust and debris and still run fine. But have a mismatch in impedance, and it's gonna end badly. Just had this happen on a 1979 Marshall 100w head I have ridden hard and put away wet. A bad tube is what killed it. Otherwise, the power tranny was going to last forever.

Optimus Prime engaged in the battle of Sherma Bridge with Megatron about 4 million years ago. So he's probably 4-6 million years old.

As others have said, a failed transformer is often a symptom of another problem. Arcing motor, over-current or some other issue likely killed it.

Mike knows what’s up

Background. 208V outlet was put in when I was doing the children's clothing years ago for the silkscreen equipment and clothes dryer. Getting the 230V Dewalt compressor I got this transformer:

ACME T181052 Acme, Buck Boost Transformer, 12/24V 750va

Because I needed the dryer to work (cleaning polishing fleece blankets), I mounted the transformer on the wall and added a dryer extension cord and an outlet to it. For 5 years the compressor is plugged into the transformer outlet. Then the the transformer and dryer were alternately plugged into the 208V wall outlet.

Just did some testing.

Wall outlet is putting out 212V

Transformer outlet is putting out 96V. Enough for the dryer to work off it (just as a test) but not enough for the compressor. I can take the cover off the transformer end of the day to inspect.

Environment is essentially office space. Clean, dry.

http://forums.pelicanparts.com/uploa...1591450454.jpg

^^^^ That s your problem there, you bought it from Wile E. Coyote supplier. There stuff never works as expected!

try again to find the correct transformer
208 is a three phase configuration, that is a single phase transformer
the output on that transformer should be about 24v at 240v input

Transformers are smoke encapsulated.
Letting the smoke out seriously limits their ability to transform...;)

As I recall, Shaun has 208 single phase. This transformer adds/subrtacts 12 or 24v to the line voltage, depending on how it's wired.

Shaun - I have the specs/connections opened up in a PDF. I suspect you have it wired like this:

http://forums.pelicanparts.com/uploa...1591456176.jpg

If so, voltage measured should be approx:

Input 212v(as measured)
H4-H3 - 106v
H2-H1 - 106v
X4-X3 - 12v
X2-X1 - 12v

If not wired like that, post the wiring and the voltages measured.

Thanks Dad, I won't be able to pull it apart today but will tomorrow.

If I wired it incorrectly, would it still work for 5 years and then fail?

No. I don't think it's wired wrong. I'm not sure if it's wired with a boost of 12v or 24v

I'm hoping it's one of the 12v secondaries(which isn't a deal killer), or a loose connection.

The PDF states a 10 year warranty. FWIW

Have not sized transformers for motor loads for a long time, but how many HP is your compressor? never mind I looked at your link 5hp 22A, looks like it is rated for 31A. The starting current for that compressor motor would be pretty high.

I believe that rating is for the boost/buck portion of the transformer(12/24v)

Follow the link shaun posted and it's 30/60 amp.

Pulled transformer apart, wiring is charred. No time for inspection. More to come.

Interestingly, the dryer did work plugged into it so it may be salvageable. Or not.

first thought is undersized

So would there be a benefit to oversizing a transformer for longevity purposes?

It's probably salvageable. Check continuity with a multimeter on primary and secondary. Check the operating temp with a laser thermometer. Hot=early death. Cool=infinite life.

I'll post some pics tomorrow of the wiring.

X2 and X3 got mighty hot.

http://forums.pelicanparts.com/uploa...1591532556.jpg



http://forums.pelicanparts.com/uploa...1591532556.jpg



http://forums.pelicanparts.com/uploa...1591532556.jpg

I think you can save it. It should be hi-potted to be sure it's okay.

Put a fan on it when it runs next time...and a cooling plate too if needed.

The wires actually look good to the transformer. Looks like (from hundreds of miles away) this connection in this spot arced and failed:

http://forums.pelicanparts.com/uploa...1591545281.jpg

Looks like the smoke released from the connections, not the transformer.

If you want to test the transformer, you should get a 'continuity' reading for each individual coil to see if it burned open. Disconnect all the wires, with an ohmmeter there should be able to get a measurement at each coil (greater than infinity). X1 & X2, X3 & X4, H1 & H2, H3 & H4. The 2 X coils should read about the same, as should the 2 H coils.

Thanks '90 and Dad.

The failure is at the junction of X2 and X3. That junction burned the connector off and melted away the exposed twisted wires.

http://forums.pelicanparts.com/uploa...1591546120.jpg

http://forums.pelicanparts.com/uploa...1591545993.jpg

What gauge is this wire? How many amp breaker on this circuit?

Based on the Compressor specs, should be 30A breaker, and wire at least 10AWG.

Just looked, it's 12/3 solid Romex.

Then I suspect you can clean up the connections, and your back in business.

Any idea why it did what it did? Should I at least get the 10/3 wire?

In general, 12 wire feeds are rated for 20 amps and protected by a 20 amp breaker.

The compressor specs say it draws 22 amps, and recommend a 30 amp breaker, which would typically be #10 wire.

If it's a long way to the panel, or if there is a 20 amp breaker on #12, you should probably address this.

it's a 30A breaker. A professional electrician ran the wire 60 feet or so from the box to the new outlet which was for a silkscreen exposure unit. I think it had a 4500W metal halide bulb. Took massive amounts of e-. The brightness was incredible. I will have to look at what gauge wire the electrician ran.

The transformer is next to the outlet with the compressor.

Probably a little oxidation over time. Doesn't take much. Make them clean and shine. Maybe a little anti-ox paste.

I didn't sleep in a Holiday Inn, and I'm more familiar with Residential than Commercial, but in general the wire is sized for the load, then a breaker is sized to protect the wire, if that makes sense. #12 is generally rated for 20amp, #10 for 30amp (copper).

The specs for the compressor say 22 amp, 30amp breaker. If you have been getting by not tripping a 20 amp breaker, and it's a short run to the panel, you can probably leave well enough alone. If it's a 30 amp breaker on #12 wire, that's not allowed residential, and I suspect commercial also.

If it's a long run to the panel, you would also get less voltage drop with #10 wire.

So the #12 just goes a few feet from transformet to the outlet? Definitely swap.

If I was closer I'd grab a hunk of wire and come over.