Demo of the PSX short circuit protection

PCRR/Dave,

Nice collection but I wonder if you can simplify the wiring on the next layout you build.  You don't need to protect the accessories or the switches.  Limit your power outs to the tracks to four.  Just a suggestion.

Anyway I got answer of the PSX in conventional.  They can not be used in conventional.  So transformer control is out of the question.  Either wire them before a TPC or TIU and very the voltage through those devices.  I'm still waiting on what the minimum voltage is though.

Gary & RJR,

   I do have new LED lights in all my old 711 & 072 Lionel switches and it definitely helped with the power draw, Gary I like your idea of not safe guarding the switches or accessories, if my P2 engines are still safe guarded during a de-railment over the switches, also with your new information that the PSX will not safe guard Conventional engines, this eliminates the usage of these PSX breakers for me, I run both P2 engines and Conventional Pre War Tin Plate from my DCS hand held remote, and still want to continue doing so.  What is the problem with conventional running, what a bummer.

Gary I am not sure I understand this right, to my way of thinking these PSX units should work with either DCS or Conventional running.

PCRR/Dave

I had bought one of these with the intention to use it on a conventional layout. I'm almost  (99.99%) certain that there is a DC supply on the board, as the heart of the PSX is a microcontroller chip. I'll have to see if I can find the traces that come from the AC input and modify it so that I can power it via a small transformer. I'm interested in what the minimum AC input voltage is--- 

Am I missing something?  I replaced my old ZW's with 180w bricks to get the fast acting breakers.  I only paid 55-75 dollars a piece. They seem to pop really easy without any damages yet... and they reset quick and easy (depending on where you mount them.

woojr,

  No you are not missing anything, these PSX units are just a super great way to safe guard your layout, the bricks do work just fine.  However they are limited as to control

capability, I control a lot of old Pre War 711 Lionel swithes with my ZW by varing my amperage as needed for each switch, can't do that with a brick.  These PSX units will be great for safeguarding the complete layout, especially with ZW & KW transformers as power supplies, the instant trip function is fantastic.

PCRR/Dave

Thanks for the info and video, Gary.  Have you tested these with a half-wave fault (i.e. a robust diode in series with your shorting jumper)? It would be good to know if such a fault is quickly cleared, as it is not uncommon anymore for series diodes to be used for voltage dropping in lightning or smoke units, so such a fault is theoretically possible. About 25 years ago I was testing solid-state circuit protection in an aircraft R&D program. It worked pretty well until we tried a half-wave fault; at that point about half of the units blew the lids off of their FETs! If the switch is implemented using sufficiently robust triacs, however, it is probably OK.

Dale,

   The TVS is a good way to go also, however Gary was trying to show the new PSX units and how they automatically reset, they are a real nice piece of tecnology no doubt about it.  They are a might pricy for a big layout and the older type TVS is a lot more cost effective, especially for a larger layout.  However if I had a two or 4 track layout I would definitely take a hard look at the PSX units, they are definitely high grade technology.

PCRR/Dave

Not knocking it at all, great post and video. thank you Gary.  Again I am not sure that the super fast breaker adds any additional protection to the engine electronics. The TVS does Im sure.  This would be a good question for Dale Manquen . It does make a fault event shorter in duration so I am not sure. It certainly would add protection to branch wiring.  My Lionel bricks have very fast breakers so this product would be redundant protection for me.

Dale H

But being able to change the trip current level is an added feature.

Just for ha ha I set it at max 15 amps and still no spark

I took a good look at the on board aux supply circuitry. it's a LM7805L in the 8 pin surface mount package. I'm pretty sure I can isolate the regulator input, then power it with a 9vdc wall wart. This would make the PSX independant of the input AC power. The reason it's built like it is(command control) is because it was originally developed for DCC powered layouts. I'm going to experiment with how low I can drop the input voltage before the regulator drops out. I'll report back---

Well, here's the results of my little experiment: IT WORKS at 6.5VAC input. It functions  properly, detecting the short, shutting off the output, waiting 2 seconds and turning the output back on. I had the current set for 4.8 amps. Power was a z1000 running thru the Z-controller. I could have looked at the AC waveform, but I didn't bother, as the PSX probably doesn't care much.(DCC waveform is a square wave with varying pulse widths, and it works just fine with that).

        So, I believe that it can be used on a conventional layout, as most transformers (except that pesky CW-80) start at 5-6 volts. The ideal place for these is between the transformer and any controllers-- conventional(Z controller) or command control devices. Of course, if using a PW transformer, between it and the track.

Hope this helps----

FEC just confirmed the email I got from Traintek.  While they did not independently power the PSX, they have had it down to 5volts while running PS2 engines

Just some more followup: the microcontroller is a 16F88 PIC. according to the datasheet, minimum operating voltage is 4.0 vdc. So it will work down at 5VAC input. In reading the manual, it mentions that there is a TVS across the input AC, and its not a 33v-- it's somewhere near 20V. So be warned-- it might just fail quicker than you think. I'd seriously consider replacing it with at least one rated a few volts higher---

Just finished installing my dual PSX boards.  Had to re arrange the transformer and other stuff to comfortably fit these boards in.  Left the fast blow 10A fuse blocks in place before the PSX inputs as a last line of defense just in case PSX fails.  Wired board so a switch press restores the power rather than cycling every 2 seconds.

PSX worked like advertised upon turn on, and "found" its first short when I had my Y6b start a backup move.  The rear drivers were not properly positioned creating a short,  and instantly the headlight and passenger lights went off.  Reset engine, then PSX, and back in business.

If it saves engines then worth money.

Wonder if Tonys Train Exchange has seen a sudden up tick in PSX sales as result of video?

Good question RRMAN

It's official, you can use the PSX in conventional control as I just received a email from the designer.  The minimum voltage the PSX will work at is 6 volts AC and since most transformers start at 6-7 volts no issues.

I'm hopping the 20 volt transorb rating is RMS and as 20 volts peak or peak to peak would not work as it would clip the sin wave, reading the manual it must be RMS.  Another email question on the way.

Count me as an uptick in PSX sales as a result of the video.    I installed a PSX-2AC today on my 18' x 28' layout, covering the output of each of my two TPC-300s.  It's great, as I had been having trouble with the "welding effect" pitting my Gargraves track when something derailed, even though the outputs were protected with 10 amp fast-blow fuses.

With the PSX in place, that's all gone now.  I left the fuses in place as an extra layer of protection, but the PSX cuts the power long before the fuses can blow.

I did not install the buzzers -- the noise would be annoying to me.  Instead I went with an illuminated pushbutton to do a manual reset.  When the PSX trips, the pushbutton lights up.  (The volt and ammeter are after the PSX, so they also drop to zero when the PSX trips.)  Then hitting the lighted pushbutton resets the PSX and restores power.  See the second picture below where the square button on the left is illuminated after tripping the PSX.

Here's the PSX installed under my layout and adjacent to my small control panel.  (I use TMCC almost exclusively and control everything from the CAB-1 because my layout is kind of spread out.  So I'm not planning an extensive control panel.)

And here are the square illuminated pushbuttons, with corresponding fuses beneath. The button is lit with an internal red LED which is very red in reality even though the picture shows it as somewhat yellow. (The lower left paddle switch and square yellow light are overall 120v AC power to the layout.)

I ordered four of these and received them near a week ago. I just pulled one out of the package and tried it...18vac on the input, shorted the output, and killed it forever. In checking the other still closed packages, the one I happened to test does not have a heatsink on it like the other three, and doesn't have a connector on it for current limit selection. So I don't know what this is, but it's dead now. One of the other, same looking ones with heatsink and connectors, that I just checked works fine.

I emailed and will no doubt get a proper unit for this one, but just thought I'd mention it in case anyone orders and the unit doesn't have a heatsink or connector...don't try it.

Also, are there any specs on the status LED connections, etc. The specs are mostly words and no numbers. Kind of leaves me in the dark as to whether I can light an LED that is sort of sealed in a switch and requires 12 vdc. I am wondering if I can light it adequately with the LED status circuit connection, even though it obviously has a resistor inside the switch in series with the LED.

UPDATE!

I just got a reply from Traintek, LLC and another unit is on the way. I am very thankful for the quick response and fast fix to my problem. Good company. Just letting y'all know.

The LED in my illuminated pushbutton is a bare LED -- no resistor.  I don't have the PSX-AC instructions in front of me, but my recollection was reading that the LED driver circuit was able to directly drive an LED with no resistor needed.  So in my case, I just hooked up the pushbutton LED directly, and it worked fine.   I don't have any experience on what would happen on an LED w/resistor designed to be driven @ 12v.

Just ordered 2 of the 1ACs. They are out of the 2ACs. This is why I love this forum... what a great product.

Anyone have these wired up to a ZW? I would like to see some better pictures of how this is done. Superwarp1 the link you attached does not show this too well. Thanks for the video!

Reference this posting on how to wire ZW to these boards:

https://ogrforum.com/d...786#3963862661710786

Basically the U common goes to J1-3 and track common goes to J2-1.  ZW hot goes to J1-4 and J2-2 goes to the block center rail.

That is good advice. They say they are ok at less than 20 vac, but I took them off the board since they go out easily when operating at full CW80 output and the load suddenly disappears when the PSX breaker operates. I think a TVS across the load is probably a good place for one...a 33 volt one.

Thanks for the post Gary. Ordered mine tonight.Paypack is about 40 derailments in the cost if fuses.

"in the cost if fuses"

Fuses are definitely an expensive way top go, in the long run.  You can buy good breakers in a boating store for around $10.  If approved for boating use, they shouldn't be poor quality.

Don't worry about the TVS that is a RMS voltage reading they give in the manual and will not clip your sin wave as they are actually 40v peak to peak.  But, as mention in the manual they burn up overtime as they are not as robust as they could be.  Wouldn't hurt to ad a TVS to the output.

After many emails with the vendor and designer wiring it their way or with the Hot wire being switched will cause no issues so wire it opposite of what is shown in the manual

Great job MHK58.

The board comes with LED, if you want LED indication on your control panel you can wire them to the board

As to the 20vac sine wave, I don't have a sine wave, I have a "shark's tooth" wave with hash on it. When this source, a CW80 running 17.8 vac measured by a Fluke true RMS meter was suddenly cut loose from the load, it already shorted a tvs diode D11. So I will instead put a somewhat higher voltage tvs on the input terminals.

Not a deal breaker, just something to work around. I don't know what is meant by the "hot" wire in a ungrounded, ac system. It doesn't matter which leg you break, but I'm open to reasons...

Just terms.  Center rail is the hot rail and the outside are commons/neutrals.

If you have already blown up D11 you must of had some serious spikes.  I'm running about the same rms voltage but with a straight transformer.  Yet to burn out D11 but not really worried about it.

The CW80 strikes again!

The RMS value of the CW80's waveform may be 17.8v, the peak is probably twice that. TVS's work by turning on at the rated voltage. the power dissipated by the TVS will eventually kill it.

 I just bought 2 of the psx 1ac for my layout and all though it not a large layout I still think its big enough for 2 though? The layout measure's 28x16 with a 3x16 yard currently being added. I have 2 modern zw's with a total of 8 power house's running it for a combined total of 1440 watts. I can run 5 trains at once but usually only run 2 unless I have friends over then we run more. I run my lights and accessory off 2 1033 and 1 kw it sounds like a lot but it doesnt look like it is. Since I run command control engines only I'm going to wire these psx into 6 blocks 1 block for each main line = 3 blocks, 1 block for my roundhouse area, 1 block for my inner yard and 1 block for the new yard. So my thought in wiring in blocks is to be able to control where the power is being used at that moment such as if I'm not using the yards or roundhouse area  I can turn those blocks off and all the power will go to whatever trains are being ran at that given time. I will almost always run a long passenger trains with 12-20 heavyweights in tow, a a-b-b-a streamliner with 15 lightweights and a doubleheaded steam train with 30-40 fish belly hoppers so as you can imagine that 1440 watts go quick with the passenger trains alone. I guess I'm really asking is 2 psx will be sufficient with what I have.

"I don't know what is meant by the "hot" wire in a ungrounded, ac system. It doesn't matter which leg you break, but I'm open to reasons..."

Your are correct in your observation that in an ungrounded AC system* the legs are electrically identical.  But here's the rationale for using those terms on a layout:  Model train transformers generally have a single secondary, with one post (generally "U") connected at one end.  The other posts (generally A,B.C. &/or D) are connected to sliders that move along the winding when the corresponding lever is moved or knob is turned.  These are set to feed different blocks, which are insulated from one another by gaps of non-conductive pins.  These other posts should be connected to the center rail, to minimize (not eliminate) the possibility of shorts between them if they are set to different output voltages.  If they are connected to the outside rail, the entire train will jump the insulated gap and cause the possibility of such a short.  If they are connected to the center rail, only when rollers jump the gap is there this possibility.

*In contrast to the feed to a house, where one wire, called the "neutral" (white insulation) is usually grounded.

Excellent explanation RJR.  Ground or neutral is what we define it to be. Just like in an automobile, we talk about the car frame and all sheet metal as being "ground" to which the car battery negative (usually) is connected to, although there is no wire attaching the car frame to physical earth ground, and the other battery pole is split out to power the starter, radio, head lights etc and their return leads are attached to car frame defined as common return "ground" back to battery.

So as RJR says, we by convention defined the outside rails of Lionel track as being ground common and insulated center rail as the hot feed from the transformer.

Good on the center rail here too. My instructions show a red wire going to terminal J1-4 so I assumed that to be the switched wire...and it is. I don't see where the instructions say to switch the common wire...the diagram shows a two rail picture but says it can be considered a center rail and common, but no mention of which is which.

Anyway I like switching the center rail too.

On the issue of D11, the instructions say that some clipping may occur as the input voltage approaches 20 vac. 20 vac is 28.28 volts peak to peak. So that is a bit close...not unreasonable that noise from a triac controller on top of 18 vac will reach that and more. And why some forum folks have recommended a 33 volt peak TVS.

Enought of that. If it works for you I would leave it too, until I had an issue as I did.

My layout is similar in overall dimensions, but the track plan is such that I run only 3 trains at once, with the possibility of going to 4 trains if I carefully control speeds to avoid having one train run into the tail end of another.  I have two power sources for the track (each power source is a TPC 300 in front of a commercial transformer) and one power source for accessories/lighting.  I installed two PSX-ACs, one for each track power source, since the track is where I get "shorts" due to derailments.  I left the accessory power source with just a fast-blow fuse since I rarely see a "short" on the accessory/lighting side.

But my power sources are smaller than yours -- only 300 watts for the TPC 300 vs. 720 watts on each of your ZWs.  If you read the PSX-AC manual, its trip level can be set for up to 15.4 amps.  With my TPC 300s, I'm not likely to end up over 15 amps in normal operation, so I'm good.  But with your 720 watt ZW, you could easily go over 15.4 amps with multiple big trains, and that would trip the PSX-AC even though everything is normal.  Do you have an ammeter to see how many peak amps you are using?

I have blocks as well in my setup.  I've got smaller blocks, with a total of 23 blocks so that I can turn individual yard tracks on and off.  I put my PSX-ACs close to the power source, with TMCC Block Power Controllers (BPCs) after the PSX-AC.  In the past I've blown a trace inside a BPC due to a short, but with this arrangement the PSX-AC will protect my BPCs from a track short as well as solving the track "welding" problem on a derailment.

So bottom line -- 2 PSX-ACs lines up well with your two ZWs for track power, but only if you are using a single output from each ZW, and that output is staying under 15.4 amps.  If you are using multiple outputs from a single ZW, then you will probably need a separate PSX-AC for each output.  And if you are typically going over 15.4 amps on a single output, then you will need to figure out how to divide the load so you don't have more than 15.4 amps going through a PSX-AC.  One such approach might be to associate a PSX-AC with each block (perhaps combining the yard blocks if you don't typically pull a lot of power in the yards), assuming that each block wouldn't pull more than 15.4 amps.

 Yes I'm only using one output channel from each zw but I have been tossing the idea around of getting rid of the zw's and just running the 8 powerhouse's thru something else? or just straight to a distribution block and to the psx and accessorys from there and ditching the kw and 1033's.

 I have time to think about it cause I'm in the process of building a decent control panel, I bought (2) 0-25 vac analog panel meters and (2) 0-20 a panel meters along with n/c push button switches and l.e.d.s for track power and trip indications and various switches for 120v power in to the panel and rotary switches for street lights and accessories.

 I love wiring, adding components and installing switches then powering it all up and watching it work is the most satisfying part of the hobby for me.

Thx mhk58 for your help!!

Just order 2 today. Have to protect my toys..

Hi

I finally installed 2 of the PSX for protection of my toys. Didn't have a chance to test them. But will tomorrow. 

Just got some of these a couple weeks ago. They are now $49.95 ea. for the PSX-AC. Looks to be bit more than when this thread was started. The PSX-AC1 seems to be all they have now. I got them from Tony's Trains and also ordered the terminal kits to add the screw terminals for wiring to the boards. They were an additional $6.20 (or so) a piece for all terminals required for the PSX board. Got some reset switches from Radio Shack, will be using the manual reset feature. Thinking about getting the sonalerts from DigiKey also, probably will use them also (for a try out anyway).  Looks like a great device, can't wait to get them hooked up.

I hope everyone that posted earlier is still having good luck with these. If anyone has had any problems, noticed any quirks or other interesting developments, please post and let us know.

Thanks to ChessieFan72 for pointing me to this thread from a more recent one where the PSX was mentioned. So much excellent info on these forums, so little time!