Does anyone have any suggestions for a resettable circuit breaker for the Marx 150 watt transformer#1589.. It had a broken resettable electromagnetic circuit breaker.
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I presume you mean a Marx 1859? You are not likely to find a similar breaker. There is a thread here where the baby brother, a 1669, was retrofitted with a generic 5 Amp automotive breaker.
I did not think any of the orignal breakers were available . I was hoping for advice to a modern equivalent.
The max current for the transformer at 150 watts would depend on the maximum output voltage. Assume the voltage tops out at 16 volts then the current would be approximately 150/16 or about 9.3 amps. The closest I could find is a busman BP/CB211-10-RP a 10 amp self reset breaker available on amazon. I believe this breaker will work fine for the usual short circuit fault however I would make certain to keep the maximum working load on the transformer to about 75% of the 150 watt rating. Although I do not have the characteristics for this breaker, it may not trip instantaneously at 10 amps allowing the transformer to overheat.
Wonder if something like this would preserve the red button style and functionality:
My only question would be on how long it takes to trip. My understanding is some breakers trip faster than others. If this is a correct assumption is this ever addressed in the breaker description?
Circuit Breakers protect the transformer from excessive current draw. Yes, you can spend lots of money for fast trip times, but the general purpose breakers are sufficient for their intended purpose. If you want to understand the tripping characteristics of a particular breaker, you need to look up the data sheet for it. There, there will be pages and pages of graphs showing trip times for various situations. For the specific breaker series shown above, here is the data sheet from the manufacturer: https://www.e-t-a.com/fileadmi...2_eng/D_1658_ENG.pdf
What isn't apparent is that our trains with delicate electronics are more susceptible to damage from transient voltage spikes. TVS diodes protect against these voltage spikes caused by collapsing electromagnetic fields generated by the layout (relays, solenoids, motors, derailments etc).
A short video about those spikes:
Since the source is layout side, you want the protection layout side. Many people put them on the track, others put them on the output terminals of the transformer, and some do both!
It is easy to take TVS diodes, shape them like this so they wrap around the binding posts of a transformer.
The recommended TVS for our O Gauge trains is the 1.5KE36CA.
