My old 275 Watt ZW heating up Help.

Perhaps some of the accessories need maintenance such as motors etc. It doesn’t sound like a short but maybe you are maxing out the transformer. 

Some thoughts:

1) Any recent changes, additions or rewiring? 2) Get an ammeter and check current on each post. As rod suggested, that will tell you the load situation.

Transformers under load do run hot. Lionel transformers are about 80% efficient, which means the other 20% comes off as heat. A 275 watt transformer Could give off about 60 watts of heat. I recommend that circuit breakers be added to each of the output terminals so you do not have to worry about overloads or short circuits that the transformer’s own circuit breaker does not catch. It would not hurt to take the cover off and just take a good look around inside of it. 

Check your amp draw first and see if you’re close to maximum load, if you are start checking individual accessories.

OK thanks for the tip.

Disconnect  all the outputs and see if it still gets hot.  If so, then you should start looking inside.

That's what I was sort of thinking. I could turn on each post individually and see what I get. Thanks.

Jeff, if you haven't checked the ZW's internal circuit breaker lately it might be helpful.

from Tranz4mr’s ZW Page

16. To test the Circuit Breaker set all four handles back to zero

17. Short across the terminals B and U with a screwdriver shaft.

18. Slowly raise the B handle. The Circuit Breaker should trip within a second or so and the red light should come on.

Intetnal breaker only breaks U circuit.  You can have an overload between/among ABC&D and breaker won't open.

IMO any continuous load of more than about 150 watts will quickly overheat a ZW. Running 2 passenger trains with conventional lit cars for instance will heat them up fast. New transformers such as the Z4k are rated at output, ie 400 watts. But older ones like the zw are rated at 275 watts INPUT. Big difference.

Rod

I hadn't seen anyone comment on this but it also applies to time at load, so if you are loading it up heavy and then ran for a long time it may heat up more than you were used to.  If it is all of a sudden heating up more and ALL detail on loading etc are the same as before, yo may have an issue.  If it's heated enough to damage the winding's I think you would know pretty quickly but smell or magic smoke escaping.  You also need to consider what others are alluding to, review your actual Watt loading and then determine if you are with in reason or if you may be actually over loading the ZW. Anything over about 180W constant would probably be considered an overload situation. does not matter if it is only accessory lights either.

Lastly, if you have bad connections on your track or dirty connections, that will affect conductivity, which will increase your current draw as well.

Due to some other tasks, I haven't been able to start looking at my problem. I will say this. Both ZWs are used for lights and accessories. Therefore not all accessories are operating at the same time. In fact during this problem of a hot top to the case, I wasn't operating any accessories. I may have had my 64 bulbs worth of flood lights on as a demonstration, but again, all these things are being split up between two ZWs , thus 8 voltage posts.

Are you absolutely sure that you don't have any 2 of your 8 outlets connected together somewhere on the layout?  You never want to parallel train transformers.

Old ZWs often run hot without the breaker tripping, which is not good. The breaker often goes out of calibration, especially as they age. I've seen some that will never trip no matter how hot they get! A new breaker is required to restore proper function. Get a solid state breaker.

As other have stated  above, check your amp draw. At best, you should be pulling no more than 12 amps at 18v. That's TOTAL for the transformer!

Chris

LVHR

64 how many watt bulbs at once? lights can draw more power than you would think.

How "hot" is it getting? Warm to the touch or is the big "L" medallion on the top of the case burning you? I use a Postwar ZW (with added TVS diodes and fast blow fuses) to power my DCS/TMCC layout. After an hour of running two trains (Lionel twin AC motored F3 pulling 3 dummy units and 7 passenger cars with incandescent bulbs, & a MTH Premier 2-10-4 Texas with a 9434 Pittman motor, smoke on, pulling 12 scale SFRD refrigerator cars and a lighted caboose) the top of the case where the "L" medallion is located is warmer than body temp. IR gun says it's about 108*. Won't burn you but it feels warm.