Airpax/Sensata breaker and Z1000 controller

John, I've also noted that these instant beakers will buzz when the current through them is right around the trip point.  I believe its the nature of the magnetic coil and their electrical contacts vibrating at 60Hz when the current approaches their rating.

Their trip graph indicates that when the current through them is between 135 and 150% of their rating they may or may not trip within 1 second.  But as expected, when current exceeds this overage, they will certainly trip instantly, as is the case with a direct short.

The Z1000 is rated for 6.5A output.  150% of the Airpax 5A breaker is 6.75A

Since the Z1000 is also protected by its' internal thermal breaker, my opinion is that there's no cause for concern for damage to the transformer with the scenario you've described.

Edit  On the other hand, If the Z1000 is also powering accessories, the 5A Airpax may be passing enough current to damage train wiring if the train creates a direct short, without tripping the breaker in time to prevent such damage.  Unfortunately, since the Z1000's power is limited to ~6.5A output, the 5A Airpax may not be an ideal breaker choice.  Maybe the Lionel #91 would be better suited to the Z1000.

If no conventional operations are planned a PSX-AC series breaker would also be a good choice for the Z1000.

Hi Steve,

I tested all those breakers on a 64 W MRC Throttlepack which I bought to power the inside loop when using the layout with two transformers and all of the breakers trip instantly when there is a short.

But you are saying that the thermal breaker in the Z1000 is causing interference with the Airpax instant breaker thus causing it not to trip instantly with a short.  The 5A Airpax breaker buzzes when using the Z1000 conventionally in normal operation, but the larger ones do not.  All breakers buzz and delay tripping with a direct short.   I have one 10A, three 5A,  and one 7.5A breakers

I was going to use the 14V accessory terminals for the Fastrack Switches and possibly an uncoupler track since when operating in conventional especially at low speed there is not enough power with to trip the switches with the levers.

So, LionChief and a conventional engine to run independently on one or both loops (they are connected with a toggle switch).  Accessory power for six FT switches.

Suggestion?

Thanks Steve,

John

See my replies below in orange

@Craftech posted:

Hi Steve,

I tested all those breakers on a 64 W MRC Throttlepack which I bought to power the inside loop when using the layout with two transformers and all of the breakers trip instantly when there is a short.  This is a different transformer with different design and operating characteristics from the Z1000, so apples and oranges...

But you are saying that the thermal breaker in the Z1000 is causing interference with the Airpax instant breaker thus causing it not to trip instantly with a short.  No. When the Z1000 thermal breaker trips, it's either on or off.  To my knowledge, the Z1000 doesn't fold-back the output like some Lionel transformers do.  I'm thinking that when the direct short occurs, something is limiting the current flow through the Airpax breaker so that it's right on the edge of tripping which is what causes the buzzing.  I've replicated this condition with my ZW by placing a current limited load across the 5A breaker that's right on the edge of 5 amps and the breaker buzzes until I increase the current slightly.

The 5A Airpax breaker buzzes when using the Z1000 conventionally in normal operation, but the larger ones do not.  Do the 7.5A and 10A actually trip when the Z1000 output is shorted?

All breakers buzz and delay tripping with a direct short.   I have one 10A, three 5A,  and one 7.5A breakers.  Does this "All (5, 7.5, and 10A) breakers buzz and delay tripping with a direct short" statement apply to the Z1000?

I was going to use the 14V accessory terminals for the Fastrack Switches and possibly an uncoupler track since when operating in conventional especially at low speed there is not enough power with to trip the switches with the levers.

So, LionChief and a conventional engine to run independently on one or both loops (they are connected with a toggle switch).  Accessory power for six FT switches.

Suggestion?  Need clarifications to above statements and questions before proceeding with suggestions.

Thanks Steve,

John

This has been a very informative and illuminating discussion. It motivated me to test a 5A Airpax breaker with my Z1000 that powers my ceiling track with the G-Gauge MTH Challenger and lighted passenger cars.

I first placed the 5A Airpax between the Z1000 and TIU. Without the train moving, the resting current draw was 2.5A yet the Airpax popped everytime!! It wouldn't work.

Then I placed the Airpax between the TIU and track. The Airpax didn't pop but it continually buzzed.

Soooo...the 5A Airpax definitely did not work with the Z1000. This was a surprising finding.

I tested the Airpax with the ZW and it worked perfectly well.

(BTW, my regularly-used breakers are all the W28-XQ1A thermals )

Do the 7.5A and 10A actually trip when the Z1000 output is shorted

Yes.  Buzz then trip just like the 5A does.  Same amount of delay.  No difference.  They just don't buzz when operating normally in conventional like the 5A does.

John

@Bruce Brown posted:

Soooo...the 5A Airpax definitely did not work with the Z1000. This was a surprising finding.

I tested the Airpax with the ZW and it worked perfectly well.

(BTW, my regularly-used breakers are all the W28-XQ1A thermals )

They work perfectly fine with my KW as well, but this layout is for someone else who is a 5 year old.

John

@Craftech posted:

They work perfectly fine with my KW as well, but this layout is for someone else who is a 5 year old.

John

John,

On the layout I have for visiting children, I either use the Lionel CW80 or the MTH Z1000 with the Z Controller. The transformer/controller is then connected to the track with a simple thermal breaker that will pop in 1.5 to 2 seconds--enough to protect the transformers and prevent undue heating at the point of the derailment. I only use low-end engines with kids like the LionChief Thomas or indestructible die-cast Lionel Scout so I'm not worried about delicate electronics being fried.  Now I have the Menards 3.5 engine that I won't lose any sleep if kids destroy.

Just a thought but a KW puts out a pure sine wave at all voltages. A Z1000 has a kinda chopped output (like a lot of modern transformers). Could that be causing the issue with the buzzing?

If you're running conventional you may just want to put a 5 amp Automotive Blade Fuse on the power lead out of the Z-1000 and TVS Diode across the hot and common outputs so it will pop the fuse when the train has a derailment and does a direct short even before the 6 amp breaker on the Z-1000 kicks out. That is what I have on my layout and it has worked for me on my small layout where I don't get over half throttle. I also have TVS Diodes at all my feeder connections to the track.

@Lou1985 posted:

Just a thought but a KW puts out a pure sine wave at all voltages. A Z1000 has a kinda chopped output (like a lot of modern transformers). Could that be causing the issue with the buzzing?

Lou that's a good thought about the chopped vs. sine wave, but I tried this on a PW ZW (also pure sine wave out, confirmed waveform on oscilloscope).  5A Instant Airpax into a resistive load. Up around 5Amps the breaker buzzed.  When I increased the voltage slightly, the breaker opened.

@Craftech John, At this point I think your options for the Z1000 track outputs are:

1. Use the 5A Airpax and hope for the best and live with the buzzing (not ideal)
2. Switch to a Lionel #91 magnetic breaker with adjustable trip current (good for conventional or command)
3. Switch to an PSX-AC electronic breaker with adjustable trip current and very fast acting (good for fixed 18VAC)
4. Rely on just the breaker in the Z1000
5. As previously suggested by @Gary P use an inline fuse (Fast blow) and provide a bunch of spares.

Here are the scope pictures:

TIU output driven by Z1000:

ZW output:

Right now I have a 7.5A Airpax breaker on it and there is no buzzing.  Neither is there any buzzing with the 10A.  Does it have to be 5A?

I also have a lot of TVS diodes, but they would have to go under the FasTrack to connect to the feeders which will be located there which means removal if they blow.   Unless I put the feed terminals just outside the track (not that practical, but doable).   With my tubular track I just attach them to the lockons.  I could put them across the transformer output after the breaker, but I know that is not the best place.  Recommendation?

The in-line auto fuse holders sound like a reasonable solution if 7.5A Airpax or 10A Airpax combined with the internal breaker are not sufficient.   I have them in my garage.

What about the six hard wired Fastrack switches and the uncoupler tracks?  Should I not use the fixed 14V output on the Z1000?

Thanks for all these suggestions.

John

@Bruce Brown posted:

John,

On the layout I have for visiting children, I either use the Lionel CW80 or the MTH Z1000 with the Z Controller. The transformer/controller is then connected to the track with a simple thermal breaker that will pop in 1.5 to 2 seconds--enough to protect the transformers and prevent undue heating at the point of the derailment. I only use low-end engines with kids like the LionChief Thomas or indestructible die-cast Lionel Scout so I'm not worried about delicate electronics being fried.  Now I have the Menards 3.5 engine that I won't lose any sleep if kids destroy.

Well, he has a LionChief 0-8-0 BlueTooth from a starter set (full voltage) and an inexpensive Williams by Bachmann 44 Ton switcher (Conventional variable voltage)  So not super expensive either.

John

@Craftech  are you using the Z1000 with the variable output control or just the brick?  Also, are these the DC or 50/60Hz versions of the breakers?

@rplst8 posted:

@Craftech  are you using the Z1000 with the variable output control or just the brick?  Also, are these the DC or 50/60Hz versions of the breakers?

Z1000 with variable output and would like to use the fixed terminals on the brick for switches and uncoupler track.

It says on the breaker V 125   HZ 50/60  DC  ??? 

John

I believe, at least I found, the Z1000 brick to be a little strange. The 14v ACC terminals will match the receptacle AC Hot and Neutral. The track output is reversed with the connector for the Z controller. The output from the Z controller (RED/HOT -BLACK/Neutral) will match the ACC and receptacle Hot and Neutral.

The TIU output in the scope image also corrects the reversed brick output internally. That's why the phase is the same.

I suppose one should phase the track output if the barrel jack is cut off for brick use only.

Perhaps the issue with the breakers is being out of phase.

I used them for a single train or accessory power only on the museum layout. The amperage is ok for Lionel FasTrack switches, but not enough for MTH switches that may be fired simultaneously or switches and accessories together. Keep an eye on the load.

What was nice was the ability to preset the Z-controller output and have them come on from a Master ON/OFF switch for the layout. The Z4000 won't do that. Of course, the brick only for ACC will do that also.

John, just to confirm your 5Amp breaker is the PP11-0- ; the zero being the designation for instant trip?

EDIT, these magnetic breakers don't recognize the phase of the AC waveform passing through them, only the AC or DC current.

@Craftech posted:

It says on the breaker V 125   HZ 50/60  DC  ???

Ok, that should be the “universal” one indicated in addition to what @SteveH said above the third place of the part number should be a “1” to indicate series trip.

The fourth position that Steve mentioned should be an “0” could also be a “69” for the 50/60Hz only version.

@Craftech posted:

Z1000 with variable output and would like to use the fixed terminals on the brick for switches and uncoupler track.

So I’ve only been considering these breakers (personally) for full voltage scenarios when using DCS or TMCC/Legacy in command mode.  When using a variable voltage, the internal resistance of the breaker itself could impede the flow of current during a short if the voltage is not high enough.

The fact that works with the KW is likely because the thermal breaker there is of a lower resistance than that in the Z1000.

@SteveH posted:

John, just to confirm your 5Amp breaker is the PP11-0- ; the zero being the designation for instant trip?

EDIT, these magnetic breakers don't recognize the phase of the AC waveform passing through them, only the AC or DC current.

Yes.  Identical except for upper right hand set of numbers.  Mine is 1751R15C instead of 2028R13B

John

@rplst8 posted:

When using a variable voltage, the internal resistance of the breaker itself could impede the flow of current during a short if the voltage is not high enough.

Or the resistance of the track, or the connecting wires, or the switches/relays controlling the blocks, etc. etc. Or the internal resistance of the transformer!

But, if the resistance is high enough to limit the current to 5A at the present voltage setting, what is the problem? A "short" that draws 5A is no different than a train that draws 5A, as far as the breaker is concerned. More importantly, there is no way to tell the conditions apart, not with the technology we have available in the O gauge world anyway.

I think this topic is WAYYYYY overworried. For a child's train set the Z-1000 is fine the way it is.

This is the breaker that inexplicably would not work with the Z1000:

@PLCProf posted:

Or the resistance of the track, or the connecting wires, or the switches/relays controlling the blocks, etc. etc. Or the internal resistance of the transformer!

But, if the resistance is high enough to limit the current to 5A at the present voltage setting, what is the problem? A "short" that draws 5A is no different than a train that draws 5A, as far as the breaker is concerned. More importantly, there is no way to tell the conditions apart, not with the technology we have available in the O gauge world anyway.

I think this topic is WAYYYYY overworried. For a child's train set the Z-1000 is fine the way it is.

Prof,

The purpose of the Airpax instant breakers from Sensata is to protect the sensitive electronics in the TIU and the Locomotives with DCS (and maybe Legacy too) caused when an engine derails on the track.  There are all sorts of large voltage fluctuations that happen during a short when there are sparks flying.  Typically a TVS diode would help, but as @Adrian! has demonstrated, the TVS diodes only protect the devices if they are located very close to the device it’s protecting (i.e. less than an inch).  One of the problems is that thermal breakers that are normally found in post war transformers (and some modern ones) is that they are much too slow to trip when a derailment happens and the load is connecting and disconnecting while the momentum of the train pushes the wreck down the track.  Instead, the thermal breakers are there to protect the transformer windings from overheating and melting the varnish that insulates them.  

Since it’s the repeated spikes that typically kill sensitive electronics, tripping a breaker as fast as possible lessens the probability that damage can occur.

What we’re seeing here I think is that the instant breakers should be sized smaller that the capability of the transformers ability to supply current during a short, since a short is not necessarily 0 Ohms.

@PLCProf posted:

Or the resistance of the track, or the connecting wires, or the switches/relays controlling the blocks, etc. etc. Or the internal resistance of the transformer!

But, if the resistance is high enough to limit the current to 5A at the present voltage setting, what is the problem? A "short" that draws 5A is no different than a train that draws 5A, as far as the breaker is concerned. More importantly, there is no way to tell the conditions apart, not with the technology we have available in the O gauge world anyway.

I think this topic is WAYYYYY overworried. For a child's train set the Z-1000 is fine the way it is.

So what about using the 14V accessory terminals on the brick to power the six Fastrack switches and two uncoupling tracks while using the variable voltage terminals for the trains?   Again - Handle cranked up to full voltage for the LC and variable voltage for the WBB Conventional switcher.

John

@Craftech posted:

So what about using the 14V accessory terminals on the brick to power the six Fastrack switches and two uncoupling tracks while using the variable voltage terminals for the trains?   Again - Handle cranked up to full voltage for the LC and variable voltage for the WBB Conventional switcher.

John

John, many people say that protecting the accessories on a separate  accessory bus is unnecessary.  In my experience some degree of protection does minimize the potential for, and the severity of damage that I have seen occur when only relying on a thermal breaker.  I believe you understand this which is why you're wanting to go the more difficult route of adding some precautions.

Uncouplers are prone to overheating if powered too long, but not very susceptible to damage from typical model railroad voltage spikes. I believe that since the electronics in FasTrack switches are vulnerable to voltage spikes in the same way as are the electronics in a train, they can be protected similarly.  Some precautions are prudent to address these two different issues independently.  I would suggest spiting the accessory bus coming off the Z1000 accessory terminals into two branches, one for the switches and one for the uncouplers.

To optimize protection of the switches, TVS diodes could be installed near each one.  But, without the aid of an Airpax Instant breaker (since the minimum Instant available rating is 5Amps), a Lionel #91 magnetic breaker (with adjustable trip current) could be used.  If you would prefer, a fast acting fuse would be another alternative on the switch branch.

On the uncoupler branch, install a Bourns MF-R050 PTC re-settable fuse in series with each uncoupler to prevent overheating its coil (caused by sticking buttons or holding it on too long).  Installing one PTC for each individual uncoupler would allow more use time of sequential uncouplers without as much waiting for the PTC to cool between uses.  With individual uncoupler protection, there is no need for a master breaker or fuse on the uncoupler branch, powered by the the Z1000.

Any other accessories with an electromagnetic coil can be protected with a PTC and should be on the same branch as the uncouplers. Incandescent lights could go on this same branch.

Any accessories with electronics would do best on the branch with the switch turnouts.

When choosing a mounting location for the PTCs keep in mind that they do get hot when overloaded.

For protecting the LionChief locomotive electronics I stand by my previous recommendations for Lionel #91 magnetic breaker for variable voltages and PSX-AC for fixed voltage.  Secondarily would be fast acting fuses.

@SteveH posted:

John, many people say that protecting the accessories on a separate  accessory bus is unnecessary.  In my experience some degree of protection does minimize the potential for, and the severity of damage that I have seen occur when only relying on a thermal breaker.  I believe you understand this which is why you're wanting to go the more difficult route of adding some precautions.

Uncouplers are prone to overheating if powered too long, but not very susceptible to damage from typical model railroad voltage spikes. I believe that since the electronics in FasTrack switches are vulnerable to voltage spikes in the same way as are the electronics in a train, they can be protected similarly.  Some precautions are prudent to address these two different issues independently.  I would suggest spiting the accessory bus coming off the Z1000 accessory terminals into two branches, one for the switches and one for the uncouplers.

To optimize protection of the switches, TVS diodes could be installed near each one.  But, without the aid of an Airpax Instant breaker (since the minimum Instant available rating is 5Amps), a Lionel #91 magnetic breaker (with adjustable trip current) could be used.  If you would prefer, a fast acting fuse would be another alternative on the switch branch.

On the uncoupler branch, install a Bourns MF-R050 PTC re-settable fuse in series with each uncoupler to prevent overheating its coil (caused by sticking buttons or holding it on too long).  Installing one PTC for each individual uncoupler would allow more use time of sequential uncouplers without as much waiting for the PTC to cool between uses.  With individual uncoupler protection, there is no need for a master breaker or fuse on the uncoupler branch, powered by the the Z1000.

Any other accessories with an electromagnetic coil can be protected with a PTC and should be on the same branch as the uncouplers. Incandescent lights could go on this same branch.

Any accessories with electronics would do best on the branch with the switch turnouts.

When choosing a mounting location for the PTCs keep in mind that they do get hot when overloaded.

For protecting the LionChief locomotive electronics I stand by my previous recommendations for Lionel #91 magnetic breaker for variable voltages and PSX-AC for fixed voltage.  Secondarily would be fast acting fuses.

That sounds very reasonable.  Thanks Steve.  I think I will do just that.

John

@SteveH posted:

Secondarily would be fast acting fuses.

Tried this with ordinary 5A automotive blade type fuses and the center and outer rail shorted  They did not blow at all, but rather the brick hummed like it was ready to eventually trip.

I guess I need to order fast acting fuses although I don't know why the ordinary 5A fuses wouldn't blow eventually, but they did not.

John

@Craftech There may be enough resistance in the overall circuit to limit the shorted condition current to right around 5 amps.  When you order the 5 amp fast acting fuses, I'd suggest also ordering some 4 amp fast blow fuses too.  4 amps should still be enough current to run either of these trains under normal conditions.

@SteveH posted:

@Craftech There may be enough resistance in the overall circuit to limit the shorted condition current to right around 5 amps.  When you order the 5 amp fast acting fuses, I'd suggest also ordering some 4 amp fast blow fuses too.  4 amps should still be enough current to run either of these trains under normal conditions.

I saw 2A and 3A not 4A

John

@Craftech  Here's a wide selection of 4 Amp fast acting fuses in different types of casings:

https://octopart.com/search?q=...ency=USD&specs=0

It's fine if they're rated for 120 or 250V, this is their max voltage rating.  They will still blow when their amperage rating is exceeded.

I think I have resolved the problem of the Airpax Sensata breaker not working with the Z1000.

After discovering that the Z1000 was phased incorrectly with another (MRC) transformer I cut off the plug on the Z1000 and reversed the hot and neutral wires.  That solved the phasing issue.

Out of curiosity I removed the inline 4A FA fuse holder and put a 5A Airpax Sensata circuit breaker in it's place.  No humming.  Then I repeatedly shorted the center and outer rails and it tripped immediately each and every time.

Is it possible that the incorrect polarity in the plug was causing an internal problem with the windings?  Either way, it beats the heck out of replacing fuses.

John

Maybe there was current leaking through the out of phase transformer.

@rplst8 posted:

Maybe there was current leaking through the out of phase transformer.

Bruce had the same experience with the Airpax/Sensata breaker not working with his Z1000 when he tested it. (see above).

John

The good news is that the 7.5 A version of the breaker seems to work just fine with the Z1000, PowerHouse and other full-sine-wave transformers. (I haven't tested the breaker on the chopped-sine-wave ones, namely the CW80 and Z Controller)

The 5 A one also buzzed for me in one instance using the ZW. I don't think the 5-amper likes toy trains in general!

Even though most toy trains pull less than 5A, there is no harm going to the larger 7.5A version since it will pop just about as quickly on a short.

BTW, in comparing the built-in breakers on various transformers and bricks, the 180-Watt Lionel PowerHouse breaker is, by far, the most responsive. Slightly less instantaneous compared to the Airpax/Sensata, for all intents and purposes the PowerHouse breaker is quite sufficient to quickly kill power in a derailment or other layout mishap.

Bruce, do you have a non-polarized extension cord?  I was wondering if you could reverse the plug to see if you get the same results I did.

John

Upon further experimentation the buzz came back when I put an engine under heavy load (seven heavyweight lighted cars) using the 5A breaker.  So I swapped it for the 7.5A breaker and the buzzing stopped.  I tried an A - B trip rate comparison between the 5A and 7.5A and could not detect a time delay difference with shorted rails.

But the buzzing goes on and off using a non-polarized plug when reversing the two prongs back and forth, so I believe my theory may still be valid regarding the plug on the Z1000 being wired backwards.

John

The reason you hear the buzz is when the breaker gets close to it's rated trip current with AC, and especially chopped waveforms, the magnetic trip mechanism is almost tripping.  Since it's an instant trip breaker, there isn't any delay mechanism to keep it from chattering near the limit.

As far as not noticing a delay, I have the Lionel Powerhouse 180 bricks, they trip instantly when there's a short circuit.  They're actually a little smarter than the Airpax breaker, they will allow a slow ramp up in current to go slightly over rating before it trips.  That's the circuit temporarily assuming it's a startup surge.  However, if there's an instant step up to the trip current, they trip instantly.

They still buzz.  Put a load on an engine (especially a conventional) and even the 7.5A buzzes.  I guess there is no way around it with the Z-1000 except the annoying fuses.   I actually didn't hear it with the trains running, but my 6 year old grandson said, "Pop Pop, what's that buzzing noise?"

Isn't age a *****?

John