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Been using them for almost 8 years now along with PH-180s for track power (purchased them a couple years before building a more permanent layout). They always trip before the PH-180s (but to be fair I'm using their 8 amp setting).  8 amps was my initial trial setting when first powering up the track. Nothing has ever exceeded the 8 amps during use so far and I've just left them as first installed.

My layout is command only (DCS and Legacy).  I used most of the PSX's optional features, remote LEDs, alarm, manual reset button, etc. Those are all mounted in the fascia of the layout table near the power cart.  They work quite well and as advertised like GRJ said above. No  electronic failures so far.

I have 4 connected to a ZW postwar for accessories. Three of them on 4 amps and one on 8. I removed D11 since I shorted a couple with a CW 80. In general I use the 36 volt transorbs that GRJ recommends. Maybe the 33s. I have both.

I have the sonic alerts but not installed, seems pointless and noisy since I can see if something goes dark. I forget what reset switch but they are on the boards.

Haven't actually tried the PSX AC circuit protectors, but they do seem like a great product based on forum comments like above from those who know of what they speak.  That being said, I decided to go a different, less expensive route, that by all accounts seems to offer comparable protection at a fraction of the price.  I'm talking about Airpax Instant Hydraulic-Magnetic Breakers paired with TVS Diodes.  One set of each is about $15 - 20 plus shipping.

They work equally well in conventional and command operations.  These breakers trip within 0.1 seconds of overload, have a visual trip indicator, and manual reset.

Here's a link to a recent topic about these Breakers: Airpax Snapac Hydraulic-Magnetic Circuit Breaker

If anyone has done any side by side comparisons between the PSX-AC and the Airpax Instant breakers, I'd really like to know more about your observations.

Last edited by SteveH
@SteveH posted:

If anyone has done any side by side comparisons between the PSX-AC and the Airpax Instant breakers, I'd really like to know more about your observations.

I have not done any comparisons, but the Airpax is reacting in 100 milliseconds. The PSC is microprocessor controlled, it can react in microseconds. Not even close. That's not to say 100 milliseconds isn't fast enough for us.

Last edited by turkey_hollow_rr

I don't have a PSX1-AC to measure but have measured 180 w bricks as well as TMCC Lock Ons. Both open in just over 8 milliseconds which is the time of one half of the 60 hz sine wave. Thats about as fast any breaker can open at 60hz. I would expect the PSX1-AC to be comparable.

That said 100 ms is also likely fast enough since breakers protect the transformer. TVS diodes are what protect the engine and they are much faster.


Dan, thank you for your insight.  That's kinda what I was thinking, that with TVS protection and 100ms disconnect time, there seems to be little chance of any electronics overheating and failing with the Airpax Instant & TVS combo.

[Edit: Norton posted while I was typing] I would also add that if using the PH180 bricks, my understanding is that they also have a very fast built-in microprocessor controlled overload disconnect and would also benefit from supplementary TVS.

With my 2 PW ZWs and a mix of other smaller MPC transformers, choosing the Airpax Instant breakers was a matter of sufficient protection value vs cost.  A savings of over $300.

Anyone else have any side by side comparisons?

Last edited by SteveH

I use a 5 amp resettable breaker in series with 10 amp Airpax on each TIU channel. In a derailment or other short, the Airpax trips first virtually instantly. An overload, such as in my PS 3 MUs when one engine starts in conventional and is a boat anchor, the 5 amp trips first. The Airpax will trip by shorting a 24 awg wire, where the the 5 amp thermal will just melt the wire. Works for me.

Last edited by John H

My PH180 bricks trip instantly on almost any derailment, I'm sure the one or two they didn't trip was simply because I didn't get a short that time.  Although the PSX1-AC looks good, I truthfully don't see the need in my case.

Well you are probably right for your situation but for us with home built power supplies or post war transformers this is the way to go

Last edited by superwarp1

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