WHY a hot ZW?

It might be caused by loose laminations in transformer. I think some ZWs  had the laminations welded and earlier ones were not. You might be able to tighten the side brackets that hold the secondary windings.  Loose  laminations can cause excessive eddy currents which make the transformer run warmmer.

Are they post war ZW's? Depends how hot you mean, is it too hot to touch or just a little warm? If it is too hot then you have a problem. 

Don't know who worked on your ZW's but you should make sure that the place is Lionel certified.

Lee Fritz

One reason for them getting hot is a shorted secondary turn.  Look very closely at the bare track where the rollers contact the coil.  If any of those windings are shorted together, it'll create a lot of heat, and the breaker isn't in the circuit to trip for that scenario.

Sometimes it's possible to solve the issue if it's not too bad.

Thanks for the replies.

One is from 1959 to 60 and the other is from 1965 to 66.

 The older one is the one that gets hot. They are both 275 Watt.

 The guy who did the work is a 82 year pro with transformers, been doing them for 40 years and know his stuff.  I had them both done by him before I used them. Then the one stuck a roller after 6 years on the job and I took it to him and he found the stuck roller. I never told him it always got hot because I thought it was normal.

That one is the one that has always ran warm.

When the roller got stuck it got HOT and stunk.

 The rest of the time it gets very warm but only after 30 minutes or so. About 110 degrees I think. Very warm but won't burn you.

As GRJ says probably a shorted turn ore two.  If (shellac?) insulation breaks down and flakes off then adjacent wires touch and wire heats up. Not much voltage difference between adjacent turns but there is the current that heats things up.

I would take it back and see what your repair man says. Might be able to take out the coil assembly and re varnish it. 

I don't think just dipping it in varnish will fix this.  You need to identify what exactly is causing the overheating.

The older laminated core ZWs run much hotter than the newer latter ones with the riveted more solid cores when under high load.  If it's getting real hot then it could be what John is talking about

Gentlemen,

   Both Guns and Tranz4MR are correct, if the ZW is real hot you have a problem, however some of the early 1st generation 275's run real warm compared to the later ones.  I have both older and newer 275's and a couple 250's also, the 250's never get as warm as my 1st generation 275 does.  It has however functioned perfectly for many many years.

Pine Creek/Dave

Thanks again,

 Took a look tonight and saw some turns that looked like they were touching. Tried to make some adjustments and it seems to be running okay, Don;t seem to have changed anything, I am thinking that Kent is on to something here. I also noticed that this ZW has a running humm that the other one does not.

Kent is probably the guy that would know, I think he has more experience with these than most I suspect.

I had a ZW-R with the HUMMM here is a link to the fix. It worked for mine.

ZW fix

Yesterday, one of my ZWs got so hot, I couldn’t put my hand on it for more than a few seconds.  The only reason I felt it was because, an MTH RDC would not pull its 3 dummies up a 2 percent incline.  No breakers (internal or external) tripped.  Not sure if it contributed to the problem, but shortly before this happened, I had an engine lock up due to a gear jam, but I hit the REV button on my DCS remote within about 15 seconds.

Today, I tried the ZW with no load.  With the handles at 6V or 20V, it stayed cool for a few hours.  And it put out 19.9 volts on all terminals.  I hooked it back up and ran two trains (on the A and D terminals).  Also had C set at 14 for switch machines and B set at 12 for lights.  It did get hot under load, but not so hot I could not hold my hand on it.  My other ZW (also running two trains) stayed cool as a cucumber.  After about 45 minutes the red light came on.  When I reduced the C post to zero, it went off.  And after about 30-60 seconds, I heard the breaker reset itself.

I got the transformer from Henning’s about 35 years ago and it still has the original Lionel cord so I doubt that it has ever been refurbished.

I’m thinking I will contact Harry Lutz to see if he will take it as a trade in on a refurbished ZW.

Top suspect is a shorted coil on the secondary.  This will not trip the breaker, but it will result in the ZW getting VERY hot.  I'd check the secondary where the rollers wipe, if a roller is worn down, it will short the coil and soon it will destroy the coil.  Make SURE the rollers are not worn to the arms!

Be sure to let your insurance agent know you are still running ZWs. If  the worst happens you'll be insured.

That's very harsh Alan.

HARSH!? maybe. When I was an engineer, for a short time in my engineering career, I was sent out to investigate residential damage claims; floods, fires, roof leaks, foundation and brick issues, etc.. I would write reports to the insurer about the conditions of the residence.

I know you will find this hard to believe but a big part of my investigation centered on "existing conditions." What was existing in that residence that could have caused, for example, the fire (even arson which was also handled by the fire dept.)?

If I found an electrical device as the probable source; the insurer would follow up with the insured with those infamous two words  " NO COVERAGE."

@AlanRail posted:

HARSH!? maybe. When I was an engineer, for a short time in my engineering career, I was sent out to investigate residential damage claims; floods, fires, roof leaks, foundation and brick issues, etc.. I would write reports to the insurer about the conditions of the residence.

I know you will find this hard to believe but a big part of my investigation centered on "existing conditions." What was existing in that residence that could have caused, for example, the fire (even arson which was also handled by the fire dept.)?

If I found an electrical device as the probable source; the insurer would follow up with the insured with those infamous two words  " NO COVERAGE."

  

Never heard of an exclusion or no coverage due to damage caused by an electrical device.

My brother is my insurance agent.  He sometimes uses the acronym RTGDP.  It means Read The [Gosh Darn] Policy.  You made me read (well skim through) mine.  I don’t see any exclusion for fire caused by an electrical device, but I’m going to send him a paraphrase of your post and see what he thinks.

@Lehigh74 posted:

Never heard of an exclusion or no coverage due to damage caused by an electrical device.

My brother is my insurance agent.  He sometimes uses the acronym RTGDP.  It means Read The [Gosh Darn] Policy.  You made me read (well skim through) mine.  I don’t see any exclusion for fire caused by an electrical device, but I’m going to send him a paraphrase of your post and see what he thinks.

You won't find it Bob, because it ain't there.