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NCE PowerCab - Short circuit protection - An update


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The lowest setting of a NCE EB1 is only 2.5A. This is too high for a Powercab.

Although the supplied power unit with the Powercab has some limited protection, it will continually try to reset and eventually, the Powercab will burn out.

Best Recommendation is a DCC SPecialities PSX-1 - settable down to 1.27A

 

Cheers,

Mick

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Its not the powercab which needs protection but the layout.  I am convinced that many of the DCC issues with extra switches for frog polarity switching etc could be avoided if the Bus to track current was limited to 0.75 amps by inserting .075 amp polyswitches into the feed to each power district.

I eased my fishplate issues in 00 outside by using a 0.75 amp power unit intended for N gauge instead of a 1.5 amp 00 unit.   

 

 

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17 hours ago, DavidCBroad said:

Its not the powercab which needs protection but the layout. 

 

 

 

???

The Powercab feeds the layout. If the layout shorts, there will be no damage to the layout but the Powercab will eventually die unless extra protection is added.

Common cause of a short is run-through at a point. Connecting a 12v/21W lamp in series with each frog feed is a good idea to limit the overall current.

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The Powercab provides a lot more amps than a lot of 00 equipment was designed for.  Running in to the frog end of a wrongly set live frog point puts a big strain on what ever is the weakest link in the circuit, the point blade tags usually succumb, but plunger pickups and thin brass wiper pickups can also be damaged as can tender wiring if the tender bridges the insulators.  I used 12 volt 2 amps on an outside layout and had one of the fish plates glowing red as a triple headed freight rumbled around....  

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2 minutes ago, DavidCBroad said:

The Powercab provides a lot more amps than a lot of 00 equipment was designed for.  Running in to the frog end of a wrongly set live frog point puts a big strain on what ever is the weakest link in the circuit, the point blade tags usually succumb, but plunger pickups and thin brass wiper pickups can also be damaged as can tender wiring if the tender bridges the insulators.  I used 12 volt 2 amps on an outside layout and had one of the fish plates glowing red as a triple headed freight rumbled around....  

 

 

From the Powercab manual.

If you already have a layout, your existing wiring most likely can be used without problems as long as it can handle a continuous 2 amp current.

 

Which is proof that fishplates/railjoiners should not be relied upon.........

 

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On 06/04/2019 at 18:03, newbryford said:

 

???

The Powercab feeds the layout. If the layout shorts, there will be no damage to the layout but the Powercab will eventually die unless extra protection is added.

Common cause of a short is run-through at a point. Connecting a 12v/21W lamp in series with each frog feed is a good idea to limit the overall current.

I have bought an NCE CP6 circuit protector as advised it works/activates at a low enough setting to protect the Powercab. How to wire it in is obvious, how it actually works is not.

 

Each power district runs back to the Powercab though what looks like a a big light bulb (or might be a big fuse). I would like to test it with a deliberately created short but don't want to blow up the bulb/fuse unnecessarily. Does the CP6 do a similar thing as your mentioned bulb?

 

I have run my first DCC loco via the Powercab on a very short temporary test track and now need to wire it into the layout. Any help welcome on this testing shorts, very much still a DCC novice.

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It should be quite safe to short circuit the layout if the cut out operates properly. With a big layout, such as Carlisle I usually carry something metal with me to drop on the track in case of emergency - I might be the best part of 30m away from whatever is happening but a coin on the track stops everything quite safely, a bit like emergency track circuit clips on the full size railway.

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For what it is worth - I had heard that "the PowerCab does not handle shorts gracefully" and let shorts flow unchecked. So I eventually wired in a cheap 1 amp automotive circuit breaker from Maplins, on the theory that it wasn't fast acting , but it would at least act to limit the duration of the short.

 

This seems to do something - at least before it went in a short resulted in a screen full of gibberish on the PowerCab and now you simply get a blank screen. In both cases you need to unplug and reboot the PowerCab to get the display back , but it may be some level of protection.

 

I am using the supplied 1.1amp transformer through an adaptor (because I'm a cheapskate) and no specialist circuit breaker seemed to trip at such low loads. If anyone has a better idea I would be glad to hear it (Please do not cite car light bulbs.....)

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You would think manufacturers would produce DCC controllers that protect themselves—you know, the way DC controllers have for many years... (some do, clearly NCE isn't one of them). This seems to affect systems of US origin in particular.

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I have fitted my NCE CP6 some time back after frying My Powercab, but upgraded to 1.5A lamps I think they are; if that is the original Ampage for the lamps  then they are 1.8/2.0A. I will check if you want me to but I CBA to go upstairs at the moment. Seems to work fine for me. I will need much more carefully chosen protection when I upgrade to 5A.

 

Phil

 

Edited by Mallard60022
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1 hour ago, Mallard60022 said:

I have fitted my NCE CP6 some time back after frying My Powercab, but upgraded to 1.5A lamps I think they are; if that is the original Ampage for the lamps  then they are 1.8/2.0A. I will check if you want me to but I CBA to go upstairs at the moment. Seems to work fine for me. I will need much more carefully chosen protection when I upgrade to 5A.

 

Phil

 

They are the originals at present (just as bought). The part number for the other set is given but whether that is  UK option available via Halfords who knows. What I want/need to know is are they effectively just big fuses and in the event of a short do they light up as a visual indicator of a short? Presumably if it is a bad enough short they would blow. 

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Oh yes, they glow beautifully! How do I know this? I think I got mine on the webby so I might have the contact. Those lamps have a funny name and are car parts I am sure.

Big fuses? presumably if they get too overloaded they will just burn out and cut the power to that circuit and that should include your Handset, however do not take that for Gospel as I am a numpty with trickery. 

Phil

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From what I understand these are just the same as the home-brew car light bulb circuits some use. They aren’t fuses or circuit-breakers that stop current flowing, but just a way of absorbing the extra current produced when a short occurs, and keeping it down to a ‘safe’ level until the short can be rectified/removed/stopped if I have if correct. Lots of people seem to think this is quite okay but it doesn’t sit comfortably with me, who being a bit thick in electrical matters thinks a short is a short and needs the power shutting off PDQ. But that’s just me.

 

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time for an update.

 

To summarise what I think I've learnt / worked out, The NCE PowerCab has built in Short circuit protection but will try to reset itself and if the short is not resolved promptly, the repeated shorting after attempted resets will eventually burn out the controller. (Newbryford April 6 above). Not good as I sometimes like to leave my track cleaning loco running around unsupervised.

 

the DCC SPecialities PSX-1 - settable down to 1.27A sounds good, however as far as I can tell I'd have to buy from the USA as there's no  local supply.

I'm not that keen to source from O/S as any return would be prohibitively expense given Australian Extortion Overseas postage rates for anything that won't fit in a letter. (My bad luck with technology purchases is second to none).  Second discouragement is the high total cost by the time FX rates, tax and postage are added so I've been looking for alternatives.

 

Since my layout is simple, distances are not great and instances of shorts rare, my tech savvy friend suggested a simple fast blow in line fuse with two LEDs wired, one (Red) in parallel with the fuse that will light only if the fuse blows and track is shorted, the second (Green) beyond the fuse across the track in / out power which will be lit unless the fuse blows due to a track short. Suitable resistors fitted with the LEDs will limit current flow in the event of a fuse blow.

 

As my total current draw from operations is rarely > 300mA, I figured on trying 250mA fuses first to see how I go with potential to go higher if these trip too often.

 

Any thoughts etc. appreciated, are there flaws in this solution?

 

Colin

 

 

 

 

 

 

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The NCE PowerCab reacts to a short too rapidly for an in-line fuse to be effective. Ron Solly kindly pointed me in the right direction and the issue is now fully resolved.

 

In a nutshell, the NCE proprietary solution is a Festoon Lamp(globe) of about 10W that will restrict current to under the Controller trip level #. This simple device can be adopted to drive an alarm / warning light so that current can be disconnected from the track without having the NCE Reset.

 

The configuration that I've built takes output from the PowerCab to an in-line switch then via the 10W lamp to the track.

A Bridge Rectifier is wired across the lamp to produce a DC output which is only created when the lamp is lit and there is a voltage drop across the terminals.

 

This DC output has a Capacitor (mine is 470uF, 16V) across its terminals as well as the required loads, in my case parallel wired simple buzzer and string of LEDs. It works a charm and the buzz makes sure you don't stress the PowerCab a second too long.

 

# The NCE product is a bank of 6 lamps to cover up to 6 circuits which at USD 40 + O/S Shipping/ Tax is a very expensive overkill for my single Power Cab.

My whole setup cost under $10 (of the Sunburnt Splendorous AUD kind).

 

All this was built into a recycled UK style Power Board, the photos here are of a late trial version

 

 

 

NCE PowerCab Short Protection.jpg

Edited by BWsTrains
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People may be interested to know what happened to my Power Cab a couple of years ago. I accidently built a short-circuit into a loco when I was fitting a sound decoder into it. (I had somehow got the wires from tender to engine mixed up.) I put it on the track and spent a couple of minutes unsuccessfully trying to get it to move. I then found that the screen of the Power Cab was blank and it refused to work. I sent it back to America for repair and it cost me nearly £40 for the repair and postage both ways. It was sent back with the comment "track circuit blown". It was not only repaired but the software upgraded. 

 

I recently accidentally built a short-circuit into my layout when I got wires mixed up (I really must get out of this habit) but this time, although the Power Cab got warm, it didn't blow. On the other hand, this time I realised very quickly that something was wrong and switched off at the mains socket. I wonder whether, when it was repaired, they fitted in some sort of short-circuit protection.

 

Robert

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4 hours ago, dancingderek said:

HI BWs Trains

Is there the possibility you could post a circuit diagram of your creation please? I think I can follow it vfrom the photo but I'm not sure how to wire the bridge rectifier.

 

Capture.JPG.fcd2c2fa3db52b2e96e6f22bb92a0baa.JPG

 

 

Usual health warnings apply about testing/ checking before use; DC Voltage across the Bridge outputs etc. I tested my circuit with a known 16V AC supply across the Diode inputs. Optionally you can add an LED or 2 + suitable dropping resistor in parallel with the buzzer.

 

I should add that when the circuit shown here is activated my Powercab delivered ~0.7A thru the lamp so its not something you want to ignore for any great time either!  A suitably noisy buzzer does the job.

 

Colin

 

 

 

Edited by BWsTrains
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2 hours ago, Robert Stokes said:

People may be interested to know what happened to my Power Cab a couple of years ago. I accidently built a short-circuit into a loco when I was fitting a sound decoder into it. (I had somehow got the wires from tender to engine mixed up.) I put it on the track and spent a couple of minutes unsuccessfully trying to get it to move. I then found that the screen of the Power Cab was blank and it refused to work. I sent it back to America for repair and it cost me nearly £40 for the repair and postage both ways. It was sent back with the comment "track circuit blown". It was not only repaired but the software upgraded. 

 

I recently accidentally built a short-circuit into my layout when I got wires mixed up (I really must get out of this habit) but this time, although the Power Cab got warm, it didn't blow. On the other hand, this time I realised very quickly that something was wrong and switched off at the mains socket. I wonder whether, when it was repaired, they fitted in some sort of short-circuit protection.

 

Robert

 

The PowerCab has on board short circuit protection, very sensitive in fact, but you want to avoid repeated resets of the controller. Maybe yours was a very old version which lacked that feature, how long had you had it? 

 

PS see early parts of this topic where as i recall others mention avoiding the repeated reset issue.

 

Colin

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1 hour ago, BWsTrains said:

 

Maybe yours was a very old version which lacked that feature, how long had you had it? 

 

I bought it second hand off Ebay several years ago. When bought it was the version that had only two addresses in recall (or something like that). After repair it came back with the (then) latest version of the software that had six addresses in recall (but that may not be the most modern version).

 

Robert

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2 hours ago, Robert Stokes said:

 

I bought it second hand off Ebay several years ago. When bought it was the version that had only two addresses in recall (or something like that). After repair it came back with the (then) latest version of the software that had six addresses in recall (but that may not be the most modern version).

 

Robert

 

In my version, number of Recalls is controlled in settings.

 

It would be useful not to be scrolling thru too many if you only need 2 in some situation! I turn mine down to 2 when letting the grandchildren operate the system. BTW the current manual is available on line as a pdf which makes searching much easier.

 

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9 hours ago, BWsTrains said:

 

In my version, number of Recalls is controlled in settings.

 

It would be useful not to be scrolling thru too many if you only need 2 in some situation! I turn mine down to 2 when letting the grandchildren operate the system. BTW the current manual is available on line as a pdf which makes searching much easier.

 

 

14 hours ago, BWsTrains said:

 

 

Capture.JPG.fcd2c2fa3db52b2e96e6f22bb92a0baa.JPG

 

 

Usual health warnings apply about testing/ checking before use; DC Voltage across the Bridge outputs etc. I tested my circuit with a known 16V AC supply across the Diode inputs. Optionally you can add an LED or 2 + suitable dropping resistor in parallel with the buzzer.

 

I should add that when the circuit shown here is activated my Powercab delivered ~0.7A thru the lamp so its not something you want to ignore for any great time either!  A suitably noisy buzzer does the job.

 

Colin

 

 

 

Thanks very much for this Colin. I really like the idea of a buzzer to alert me to hit the switch!

Derek

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