I have a ZW with the following, possibly related issues - appreciaite any input:
Q1: When running my ZW with 3 PW trains running simultaneously on three discrete tracks - the maximum voltage drops from a nominal 19.4VAC down to something in the 17s as maximum. Is this ‘normal’ for the maximum voltage to drop during ‘heavy’ operation? In my case the engines would be PW locos. Also the lockons would be lighted and a few of the passenger cars and a caboose. E.g. a handfull of lightbulbs. E.g. under ‘use’ the maximum voltage avail out of any one throttle is at best 17VAC and perhaps even lower at times. Reduce or remove the various loads and the maximum voltage available is back to 19.4.
Q2: Eventually when running three trains (as above) at higher speeds - the breaker will ‘pop’. Drop the throttles, wait a minute and all is back to normal. The breaker a little out of adjustment?
I think you’re probably running that transformer right around its limit. There’s a lot of variation in how much current a train draws; but postwar trains tend to draw more than modern ones. I use a rule of thumb of 5 amperes each. Lamps in the locomotives, cars, turnouts and controllers, and lockons add up, somewhere between 100 and 300 millamperes each, increasing rapidly with increasing voltage. I think its very plausible that you’re right around the 15 amperes that the circuit breaker is rated for.
It is normal for a transformer to have some internal impedance that causes the voltage to drop with increased load. You seem to be getting about 10 percent, which is reasonable. Your no-load voltage, however, is already about 10 percent down. I would expect about 21 volts with a modern 120 volts from the power line. So your line voltage may be a bit low.
Rather than try to adjust the circuit breaker, I would replace it by a 15-ampere automatically resetting automotive breaker, which you can get for a few bucks at almost any parts store. If it makes no difference, you can always reconnect the original breaker.
I went back and took a few more measurements based on your input.
I watched maximum voltage on the 4th (unused) output from the ZW. CORRECTION: It (and all the others) was dead-on at 20.0 V - NOT the 19 V I mentioned earlier. I must have had something running last night when I measured it(?) - scratch that - it’s right where it should be at 20V.
On a train by train basis running at relatively high speed it averaged approximately a little less than a 1 V DROP per train. When running three trains at speed it was, as mentioned earlier, around the mid 17s V maximum which corresponds to a bit less than a 1 V drop for each train.
Out of curiosity I removed one of the lock-on bulbs while everything was runnng and it allowed max voltage to increase by perhaps 0.10 V to 0.05V or so. Some lighted lock-ons, passenger cars, caboose, lighted engines and smoke units would of course ‘add up’ as you mentioned.
The original ZW breaker reset after anywhere from 5 to 15 minutes of 3 trains operating at speed with maximum voltage down at around 17.5 or so as measured at the one unused ZW output. So the built in breaker is operating within spec it sounds like (?). I might consider one of those automtive 15A breakekrs - been thinking about those for all my transformers anyway.
Anyway it sounds like things are indeed operating within spec. Perhaps the ZW is best left to operating two trains and some accessories rather than 3 (let alone 4) PW trains. (I have a handfull of other PW transformers and 2 modern Lionel transformers)
Thanks!
PS: Oh yeah, the house voltage was right at 120VAC. Many years ago I thought I measured it at around 117VAC but not this morning.
This is the first time I’ve run my ZW on 3 tracks on one of my ‘temporary layouts’. In the past I’ve used various combinations of my transfers. I also have a 1033 and an LW as well. I’ve refurbished all my transformers, phased them (polarized plugs) and put in solid state diodes. My future consideration is to still look into modern breakers… But since I don’t run modern hardware w/ electronnics I haven’t given it any priority yet. I also have a pair of CW80s an early and a late version. I’ve phased them as well and modified the early CW80 to correctly trigger bells/whistles like the late CW80.
All of these drive all the trains very well. My ‘experiment’ above is the first time I ran into a ‘limit’ on a transformer after refurbishing all of them.
Having the transformers that power the trains in phase with each other is good for the inevitable events when you accidentally (never deliberately) run across the gap between blocks powered by different transformer outputs. However, a transformer used for accessories operated by control rails on the track works slightly better when it is out of phase with the track transformer.
The copper-oxide rectifiers that you replaced are also solid-state diodes, with a somewhat better forward drop than modern silicon rectifiers and similar to modern Schottky diodes.
The automatically-resetting thermal circuit breakers in postwar transformers are the appropriate kind for their purpose, protecting the transformer and the wiring. Modern electronics in trains are damaged not by overcurrent but by overvoltage, the spikes that result from derailments and the aforementioned running between differently-powered blocks. The appropriate cure for this is the transient-voltage suppresor (TVS).
That said, you can do good by adding circuit breakers, to the individual outputs of multiple-output transformers, which are particularly vulnerable to damage from having their outputs connected together. Automotive circuit breakers are ideal replacements or supplements for the original Lionel breakers.