ZW(L) Transformer - Need Protection or Not?Airpax Snapac "Instant" Hydraulic-Magnetic Circuit Breaker

@Ken Gillig posted:

If yes I assume 10 AMP - correct, or higher?

Each channel on the ZW-L is already limited to 10 amps, what are you trying to protect from?

If you want any overload to remove power and the power to stay removed, then an aux breaker makes sense.  I personally don't like a transformer to keep power on for seconds if I have a derailment.  The ZW-L is better than some, but it keeps power on for around 3 seconds at 10 amps before it gives up.  On an overload, I want power off right now, and I want it to stay off until I correct the situation or decide that it's no longer a problem.

Adding something like the Airpax 10A breaker will kill power on the spot and keep it off until you decide you want it back on.

@ADCX Rob posted:

Each channel on the ZW-L is already limited to 10 amps, what are you trying to protect from?

@Ken Gillig posted:

Especially since that ZW(L) puppy of mine has already seen two trips into Lionel for warranty inconsistent voltage output issues.

My impression is, he needs TVS way more than he needs a(nother) breaker.

TVS Transient Voltage Suppressor- protects against voltage spikes- BOTH WAYS- your trains, but ALSO your expensive electronically controlled output transformer.

Knowing the ZW-L uses MOSFET transistors in a similar fashion to the control circuits used in Legacy powermasters, it's easy to see how and why they could be damaged from a voltage spike created from inductive loads and capacitance on a typical layout. All it takes is some postwar coil activated items like a gateman making 400+V spikes each time it's activated, or derailment shorts, or dozens of other common modes where voltage spikes are generated.

https://ogrforum.com/...-diodes-and-the-zw-l

Typical TVS used, one per channel or however you decide to place them.  https://www.digikey.com/en/pro...E36CALFCT-ND/1530580

@Vernon Barry posted:

My impression is, he needs TVS way more than  he needs a breaker.

Absolutely correct, he made no mention of over-voltage protection. Breakers optional, TVS mandatory.

Thanks Rob, GRJ, Vern,

I should have mentioned in my note I also have a TVSs as recommended by ORG on each transformer output of each transformer: ZW(L), and both ZW(R)s.

I guess I am now in the mindset of Gunnrunner John - kill it ASAP!

Why? My second warranty return of ZW(L) to Lionel was due to a situation where I had just finished programming a new legacy engine, went to the ZW(L) to turn off power so I could remove the engine to set from Prog to Run and return it to track. I noticed meters on the ZW(L) were frozen, then checked voltage and found zero volt outputs on all 4 ZW(L) channels.

Lionel believed I had a bad PCB board in the ZW(L) … I returned it under warranty and they did find that so Lionel replaced the board. No track power for several weeks.

My worry - was the PCB board bad from the buying start of this new ZW(L) and just got worse, or was there a spike?

I am just glad the engine I programmed did not take a hit.

It is not supposed to happen but did … hence MY QUESTION on protecting the ZW(L).

I welcome further thoughts from you three, and others from OGR. I trust you guys for useful advice!

Ken

@ADCX Rob posted:

Absolutely correct, he made no mention of over-voltage protection. Breakers optional, TVS mandatory.

To instal a faster breaker will cause other issues. First what about those moments when you get a second or two of high demand now you have a dead circuit. As you and others have said a TVS is money well spent. It also provides better protection and keeps operation interruptions at a minimum.

The Airpax 10 amp is THE gold standard as far as I'm concerned.  I had purchased another plug and play type breaker that was touted as "fast acting" and discovered that you could go to the kitchen and make a sandwich and come back before it touched off.

Airpax shuts it down instantly until you can sort it out. Real world experience here.

John

Thanks ‘That Guy’ and John for your added support insights!