Snap-Acting Hydraulic Magnetic Circuit Protector

I believe it was the 5A version.

https://www.mouser.com/Product...J%2FeXLH11GYig%3D%3D

Either way the actuators were Push-Pull.  The third number is 1 which is Fast trip.  If it is 0 it would be Instant Trip.

https://www.mouser.com/datashe...atasheet-1528227.pdf

So Instant Trip would be this one, but I believe the photo is wrong because PP means Push-Pull

https://www.mouser.com/Product...cz%252B3sqfIdQ%3D%3D

Some people bought the 7.5A version as well as the 5A version.  Recent prices have been around $45 each for these (At that price I would rather use a fuse).  We all paid roughly $12 for them so $15.11 is a very good price.

Be aware that with a Z-1000 transformer there is an incessant buzzing noise coming from these.

https://ogrforum.com/...and-z1000-controller

John

John, would you recommend the 5A or the 10A?

Truthfully, if you use the instant trip model, I'd go with 10A.  You may get nuisance trips at times with the 5A one, depending on what you actually run.

@Charlesp34 posted:

John, would you recommend the 5A or the 10A?

I ended up favoring the instant trip 7.5A version but it doesn't appear to be in stock anywhere right now.

As John said above, it depends upon what you are running.

So what are you running?

John

I have considered getting some of these 'fast-trip' units, but the trip circuit on my 135 & 180 powerhouse units seems awfully sensitive and/or fast. I know that I cannot detect times/speed below 1~20ish milliseconds, but do we know if the powerhouse breakers are fast/sensitive enough?

@Craftech posted:

Some people bought the 7.5A version as well as the 5A version.  Recent prices have been around $45 each for these (At that price I would rather use a fuse).  We all paid roughly $12 for them so $15.11 is a very good price.

See this post of mine on an earlier thread for links to the Sensata/Airpax SNAPAK instant-trip magnetic circuit breakers as sold by Digikey and OnlineComponents.com. Digikey and Mouser seem to have the best prices.

@Craftech posted:

I ended up favoring the instant trip 7.5A version but it doesn't appear to be in stock anywhere right now.

As John said above, it depends upon what you are running.

So what are you running?

John

Digikey has a very limited number of 7.5A breakers available. See my post above for a link to a link.

@woodsyT posted:

I have considered getting some of these 'fast-trip' units, but the trip circuit on my 135 & 180 powerhouse units seems awfully sensitive and/or fast. I know that I cannot detect times/speed below 1~20ish milliseconds, but do we know if the powerhouse breakers are fast/sensitive enough?

@gunrunnerjohn has said multiple times that he thinks the PH180 has excellent circuit breakers built-in.

@woodsyT posted:

I have considered getting some of these 'fast-trip' units, but the trip circuit on my 135 & 180 powerhouse units seems awfully sensitive and/or fast. I know that I cannot detect times/speed below 1~20ish milliseconds, but do we know if the powerhouse breakers are fast/sensitive enough?

I'm unimpressed with the breaker on the PH135, it's an ordinary thermal breaker and isn't that fast.  It's there more to protect the transformer than the load.  I can take many seconds to trip, even with a significant current over the trip value.  I've posted the trip curves for common thermal breakers many times, and I can't really recommend them for good protection.

OTOH, the breaker on the PH180 is an excellent performing unit, IMO you don't need any additional circuit protection.  For a direct short across the PH180, the trip time will be a few milliseconds.  The only thing faster would be an electronic switch.

The PH180 (at least the older version, don't know what's in the new version) has a two stage circuit protection circuit.  It has a slow rise detector that prevents nuisance trips, but will trip if the surge is longer.  This prevents it from tripping from a brief surge like starting a couple of Pulmore motors in your PW diesel.  The second stage is a lower gain stage, but acts instantly for a direct short circuit at the 10A rating.

I've been using the PH180 bricks for many years, and my current layout as well as our modular club layout is powered with them.  I've never seen them fail to trip instantly on a derailment that crosses the center and outside rails.

Silly question but, how should I be connecting this circuit protector to my layout?

Thank you.

@Charlesp34 posted:

Silly question but, how should I be connecting this circuit protector to my layout?

Thank you.

In series, in the hot terminal or lead, (not common) wiring between transformer and track.

example with a ZW

Also, user @CAPPilot made some excellent posts and diagrams that really helped me when I first started.

https://ogrforum.com/...54#83790477385088054

Thank you everyone for your input. I have one last question; how are you mounting the circuit breaker? I could use some ideas.

I have mine mounted in a project box that I use to connect my ZW to my track (I have a tiny layout and a test track). I have one breaker for each main throttle. For accessory feeds I just use PTCs (PolySwitches) on terminal blocks (in the small project box on the left).

The second picture shows the breakers above the throttle inputs. I chose the push-pull configuration breakers, pulling on them opens the circuit manually. I tested them with a dead short and they are instant trip.

I have a 5A & 8A magnetic breaker. I switch to the 8A when I get consistent buzzing from when I blow the horn, et cetera. The variable hot from the transformer goes to the SPDT. One side of the SPDT output goes to the 5A breaker and the other goes to the 8A breaker. The outputs of the breakers are wired to the same terminal strip.

(Please excuse the electrician's/electrical engineer's nightmare.)