Short circuit protection for NCE Power Cab

[Gruffalo]

If I understand their website correctly, the DCC Specialists PSX-4 is a combined board with 4 individual circuit breakers? Can anyone confirm please?

 

If at first you don't succeed, read the bl***y manual! I have answered my own question by going on the DCC Specialists website.

Edited April 11, 2013 by Gruffalo

[jukebox]

Yes, the PSX-2/3/4 are just mutliple PCBs identical to the PSX-1, but still attached to one another on the "long" face.

 

[BRealistic]

I'd be so obliged if someone could explain why/when and how circuit breakers are needed to protect a powercab? Don't think I've come across this requirement in all I've been reading about starting with DCC.

 

Just to explain, I'm an 'electrical illiterate'... and have a powercab which, for the moment, I use only to feed an oval test track (OO code 75). In time, my 'proper(continuous, in the garage)layout' will come. It'll have 19 turnouts (to be switched manually, with those juicers being used to sort polarity) on the scenic side and doubtless half a dozen or so in a fiddle yard, and it's not occurred to me that I should be introducing circuit breakers somewhere 'along the line'!

 

Ignorance can be bliss... but I'd hate to think I could put my powercab at risk!!

 

To say the least, any guidance would be most gratefully received!

[RedgateModels]

Hi Alan,

 

The powercab does not handle shorts particularly gracefully. A short can and often does cause the handset to reset. This is particularly evident if you plug a second throttle into the system, they can stop talking to each other resulting in needing to play around resetting cab addresses to get you up and running again. In any case you don't want your handset resetting really. So a cut-out module is a good idea IMHO to protect the powercab from shorts.

 

If you have a large layout it is a good idea to split it up into sections, each fed by a cut-out device from the handset so that if you get a short say on loop 1 trains will continue to run on loops 2 etc. None of this is essential, but out in place to make operation easier.

 

On my exhibition layouts I have each board protected by it's own cut-out and as I use DCC operated points the accessory decoders are fed from before the cut-out so they can still be switched following a track short, but that's my preference not yours

 

Hope that helps

 

Ian

[BromsMods]

The powercab does not handle shorts particularly gracefully. A short can and often does cause the handset to reset.

 

Or worse!! Having seen the results of what some shorts can do to the PowerCab, and having had to repair them, I would always recommend the use of at least one circuit breaker for any DCC system as no system is totally immune.

[RedgateModels]

Thanks for that John, although any amount of electonic protection won't save your Powercab from impact damage eh John

 

(for the rest of you I dropped my handset and cracked the LCD screen resulting in John having to replace the whole PCB, which he did by return )

[Gilbert]

You can set routes from within the PowerCab - this is standard functionaility using what are called macros.

 

As for circuit breakers I would recommend the PSX-1 from DCC Specialities (stocked by Digitrains) - not only does it work extremely quickly but can be set at a sufficiently low level to protect the PowerCab.

Can I endorse the PSX-1 solution - I have them wired in with LEDs and a re-set button as  the NCE instructions suggest and they work well (also on my Lenz system) - I thunk an audible warning or brighter light can also be wired in if required.

Chris

Edited April 12, 2013 by Gilbert

[BromsMods]

Thanks for that John, although any amount of electonic protection won't save your Powercab from impact damage eh John

 

(for the rest of you I dropped my handset and cracked the LCD screen resulting in John having to replace the whole PCB, which he did by return )

 

 I wasn't going to mention that, Ian!!!

 

Actually the PowerCab is very robust and I haven't had many "impact damage" PowerCabs to repair.  If anything is damaged it is probably the LCD screen, but again, very rare and, with more recent versions of the handset, reasonably easy to replace.

Edited April 12, 2013 by BromsMods

[BRealistic]

That's so helpful, Ian. Thanks everso. Not sure I'll be splitting the layout into sections as I reckon I'll be the only one ever to use it... with just the one powercab!

 

I take it the circuit breaker should be 'inserted' between the powercab and the 'bus wires'(2, in T formation)? Oh, Chris's comment is telling me what I should be doing... reading the NCE instructionns!!!! Now isn't that a good idea! I only read as much as I needed to get started with the test track!

 

Cheers guys. At least one PSX-1 is on my shopping list!

Edited April 12, 2013 by BRealistic

[Gruffalo]

That's so helpful, Ian. Thanks everso. Not sure I'll be splitting the layout into sections as I reckon I'll be the only one ever to use it... with just the one powercab!

 

I take it the circuit breaker should be 'inserted' between the powercab and the 'bus wires'(2, in T formation)? Oh, Chris's comment is telling me what I should be doing... reading the NCE instructionns!!!! Now isn't that a good idea! I only read as much as I needed to get started with the test track!

 

Cheers guys. At least one PSX-1 is on my shopping list!

With 50m of track, a terminus and twin loops, I think a PSX-4 is what I need. If I expand my PowerCab, I can then separate the 5A track feed from the expansion unit, I will be ready for suitable power zones without the need to reconfigure later. Per circuit, the PSX-4 works out 20% or so cheaper than individual breakers. 

[BRealistic]

You think you've got it sussed, feel good inside, have a little surf to 'double check' (not that I disbelieve anything said here!), and find some info that causes confusion!

 

What do you (experienced) guys think of this 'statement'made only a month or so ago on a US site...

 

http://www.mrdccu.com/curriculum/nce/101.htm

 

How about a circuit protector for my PowerCab?

NCE designed the CP-6 set of bulbs as a way to isolate sections of your layout with the PowerCab. This works, but lacks elegance.

Bruce tried the PSx series of circuit breakers and found that they would NOT work as delivered, even with the jumpers set (as discussed above) for 1.27 amps. The PSx tripped before the PowerCab, but then when it auto reset, the PowerCab shut down. SO, Bruce tried adding the manual reset push button (a normally closed push button across J7 pin 1 and J7 pin 2). IT WORKS! A short on the layout trips the PSx. Clearing the short and pressing the button caused Bruce's Tsunami equipped loco to pick up where it left off motion, sound and light wise!

Bruce recommends jumpering J7 Pin 3 to J7 Pin 4 to activate the low power booster program within the PSx.

Feb 2013

[BromsMods]

You think you've got it sussed, feel good inside, have a little surf to 'double check' (not that I disbelieve anything said here!), and find some info that causes confusion!

 

What do you (experienced) guys think of this 'statement'made only a month or so ago on a US site...

 

http://www.mrdccu.com/curriculum/nce/101.htm

 

How about a circuit protector for my PowerCab?

NCE designed the CP-6 set of bulbs as a way to isolate sections of your layout with the PowerCab. This works, but lacks elegance.

Bruce tried the PSx series of circuit breakers and found that they would NOT work as delivered, even with the jumpers set (as discussed above) for 1.27 amps. The PSx tripped before the PowerCab, but then when it auto reset, the PowerCab shut down. SO, Bruce tried adding the manual reset push button (a normally closed push button across J7 pin 1 and J7 pin 2). IT WORKS! A short on the layout trips the PSx. Clearing the short and pressing the button caused Bruce's Tsunami equipped loco to pick up where it left off motion, sound and light wise!

Bruce recommends jumpering J7 Pin 3 to J7 Pin 4 to activate the low power booster program within the PSx.

Feb 2013

 

That's fine.  Bear in mind that the CP6 was never intended as a circuit BREAKER only as a circuit PROTECTOR, i.e. it won't actually shut down the power to the power district but will illuminate the bulb(s) to show where there is a problem and also protect the PowerCab.

[BRealistic]

What set me back a little, John, was that the chap called Bruce had to 'do something' to the PSX (as delivered) to make it 'work properly'. Not just adding a manual reset button (how he did it, I don't know!) but recommending, too, that a couple of pins are 'jumpered' to activate the 'low power booster programme'. Double Dutch to me, I'm afraid!

[BromsMods]

It's actually in the PSX manual, Alan, where it describes what each jumper does:

 

J7-1 and J7-2 are the auto/manual reset input. If the connections are open, the breaker will automatically

try to reset every two seconds. If the terminals are connected together (like a SPST toggle switch or a N/C

push button switch), then the breaker will remain off after a short until the connection from J7-1 to J7-2 is

momentarily opened.

 

So linking the two connections together provides a manual rather than an automatic reset.

 

 

[BRealistic]

Thankyou John. Sounds easy peasy... but is it??!!

[BromsMods]

Thankyou John. Sounds easy peasy... but is it??!!

 

Of course!!!

[North Bridge]

It's actually in the PSX manual, Alan, where it describes what each jumper does:

 

J7-1 and J7-2 are the auto/manual reset input. If the connections are open, the breaker will automatically

try to reset every two seconds. If the terminals are connected together (like a SPST toggle switch or a N/C

push button switch), then the breaker will remain off after a short until the connection from J7-1 to J7-2 is

momentarily opened.

 

So linking the two connections together provides a manual rather than an automatic reset.

 

 

Hi folks,

 

Much of interest appears to have come out of my original enquiry! I've beefed up the wiring as suggested and that seems to have cured the problems originally outlined (i.e. NCE Power Cab not fully detecting short circuits). Thanks for all the really helpful suggestions.

 

I also installed a PSX-1 circiut breaker and it is here I've come across another problem. Installed as it came (i.e. with no jumpers) it worked fine - i.e. power cut off when short occurred and then re-connected 2 seconds later. I decided to wire in the manual reset option by connecting a push-to-break switch across J7-1 and J7-2 as per the instructions. It is here that a problem has occurred. To test the effect, first I soldered 2 wires to J7-1 and J7-2 of the board. I held the other ends of these together and then created a short (coin across the rails). The power output LED went out and the short detected LED D6 came on - all as it should. When I separated the 2 wires, the power was also reset as it should. I also tested my switch to ensure it was of the push to break variety (that's OK).

 

I then wired in the switch itself. When a short was created, power was cut off OK (i.e. LED D6 illuminated). However, when the swith was pressed (i.e. circuit across J7-1 and J7-2 now open), LED D6 stays on (and power output LED off)! The only way I can cancel the short is to disconnect mains power and turn on at the mains again. I've since disconnected the push to make switch - in effect restoring the factory configuration, and still, when a short occurs (i.e. J7-1 to J7-2 should be open), power does not restore after 2 seconds - D6 just stays on all the time. Clearly, things are not now working as they should.....

 

I tried re-setting all CVs to factory values (i.e. CV63 to 42) and the problem still persists (though there doesn't appear to be a CV controlling this function anyway - just trying to exclude all potential causes). Can anyone offer any suggestions? I can't see that I've done anything incorrectly - is it possible that my PSX-1 may have a fault?

 

Many thanks in anticipation.

 

Karl Crowther

[ColinK]

I've recently finished wiring my small urban terminus layout and only just found this thread. I'm a beginner in this area, but if it helps and hopefully I've got it right.

I'm using an NCE Power Pro with three handheld cabs. Following advice from Digitrains (thanks guys) I've divided the layout into five power zones, main line, branch line, goods yard etc. it is quite possible to have someone driving a train in each zone all at the same time. I've put a NCE EB1 circuit breaker in each power zone, so if there is a short in one power zone, the rest of the layout should keep running. This is important to me as I will be running sound equipped locos at exhibitions and don't want everything to stop and the locos go quiet if something/someone goes wrong.

All the points are hand operated (piano wire in a grove) with the frog polarity changed by juicers.

It has blown my budget, but if works reliably I'll be happy.

Test running has been encouraging with everything working as advertised so far.

I painted the rail sides 'rust' today. Once its dried i'll try running locos through the points the wrong way and se what happens.

[Ravenser]

Can anyone give a bit of advice/clarification on this issue?

 

I have a Powercab , and the power supply is the US transformer it came with, plugged in via an international plug adapter (with part of the plastic rim/ring cut away so the transformer fits - but nothing electrical exposed of course). According to the markings on the base this delivers 1.1 amps

 

At present there is no breaker and when anything derails or goes the wrong way into a point it wipes /scrambles the display and I have to pull out the lead and reboot the system. This is an irritation , but I'm more worried about the suggestion shorts can damage the Powercab's electronics (I've seen it suggested the Powercab doesn't actually shut off power but just limits it?)

 

So I'm thinking of fitting a circuit braker but none seem low enough ampage. The NCE EB1 breaker is specifically listed on the nearest DCC supplier's website as "not suitable for the Powercab". (Thought EB1 was a rebuilt Shildon-Newport electric but there you go...) The PSX-1 seems to have a minimum trip level of 1.27 amps - so I don't think that will work either? 

 

All I can find - dimly remembering a comment long ago that Maplins sold fast acting circuit breakers that were far cheaper than the specialist commercial products - is this: 

http://www.maplin.co.uk/auto-reset-circuit-breakers-493

 

The 1.0amp version would presumably be low enough to trip with a 1.1amp transformer?

 

Even if the Powercab trips faster , it would presumably act to protect the Powercab itself from a sustained short - which is my biggest concern at the moment

 

I'm an electrical ignoramus so I may be missing something fundamental here...

 

 For clarity , the layout is 2 boards, each 4'3" long, the traction bus is two lengths of solid core mains cable , linke to the power cab panel /board connectors by bits of  0.2/24 "5amp" wire , droppers are a minimum of "3amp" (0.2/16) wire, and there is at least one and generally two droppers to every piece of rail . Interboard connection is via bulgin plugs and 7 core cable from Maplins. So inadequete gauge wiring shouldn't be an issue here.

 

 

I'd be grateful for comments/views /help before I drive to the nearest large town with a branch of Maplins to buy one. Or even 2 (one for each board)

Edited July 22, 2013 by Ravenser

[Ravenser]

Can anyone give a bit of advice/clarification on this issue?

 

I have a Powercab , and the power supply is the US transformer it came with, plugged in via an international plug adapter (with part of the plastic rim/ring cut away so the transformer fits - but nothing electrical exposed of course). According to the markings on the base this delivers 1.1 amps

 

At present there is no breaker and when anything derails or goes the wrong way into a point it wipes /scrambles the display and I have to pull out the lead and reboot the system. This is an irritation , but I'm more worried about the suggestion shorts can damage the Powercab's electronics (I've seen it suggested the Powercab doesn't actually shut off power but just limits it?)

 

So I'm thinking of fitting a circuit braker but none seem low enough ampage. The NCE EB1 breaker is specifically listed on the nearest DCC supplier's website as "not suitable for the Powercab". (Thought EB1 was a rebuilt Shildon-Newport electric but there you go...) The PSX-1 seems to have a minimum trip level of 1.27 amps - so I don't think that will work either? 

 

All I can find - dimly remembering a comment long ago that Maplins sold fast acting circuit breakers that were far cheaper than the specialist commercial products - is this: 

http://www.maplin.co.uk/auto-reset-circuit-breakers-493

 

The 1.0amp version would presumably be low enough to trip with a 1.1amp transformer?

 

Even if the Powercab trips faster , it would presumably act to protect the Powercab itself from a sustained short - which is my biggest concern at the moment

 

I'm an electrical ignoramus so I may be missing something fundamental here...

 

 For clarity , the layout is 2 boards, each 4'3" long, the traction bus is two lengths of solid core mains cable , linke to the power cab panel /board connectors by bits of  0.2/24 "5amp" wire , droppers are a minimum of "3amp" (0.2/16) wire, and there is at least one and generally two droppers to every piece of rail . Interboard connection is via bulgin plugs and 7 core cable from Maplins. So inadequete gauge wiring shouldn't be an issue here.

 

 

I'd be grateful for comments/views /help before I drive to the nearest large town with a branch of Maplins to buy one. Or even 2 (one for each board)

 

 

Anyone have any views on this, as I shall probably be going near Maplins tomorrow?

 

a) will the original US-supplied transformer at 1.1amps actually trip a PSX-1? 

b] Will the Maplins circuit breakers do any good?

[SHMD]

a/ I don't use any of the equipment you have, (or even seen it!), so I cant comment here.

b/ Again, I cant help.

 

Not much use - sorry.

 

 

Some comments though,

 

The 1.1 Amps, on the transformer, is the value that the manufacturers have deemed to be safe AND also the value that it can deliver whilst still maintaining a voltage that is within spec for the rest of the circuit. The more amps you pull out of it the less the voltage is available at the terminals!

 

You seem to be wanting to size the circuit breaker to match the transformer/PSU.

You really need to be sizing the circuit breaker to match the load. What gauge are you using, N, 00 or O? Do you ever double head?

Work out your maximum normal current demand and add, say, %10.

 

What you are wanting to do is (dare I say it) another complexity to DCC.

 

 

Finally, I can only suggest you experiment and report your findings.

 

 

Kev.

(Sorry I didn't reply earlier but I was hoping to let someone with more experience to reply first!)

[Rob F]

I have a PowerCab and after a few startup issues reported on here, I have generally been very pleased with it. The short-circuit protection is very poor though for such an otherwise well thought out piece of kit. I switched from an old Lenz Compact, which in all other respects is primitive compared to the NCE device, yet when there was a short all the power to the layout was cut very quickly. The short could then be removed , the reset button pressed and away you go. No need to buy extra devices for short circuit protection, just a very simple system that worked well.

 

Is there any reason NCE coudn't do the same?

 

ROB

[Lochinvar]

Yikes!  I came across this thread recently and have been reading it with a growing sense of alarm. In the 2 yrs or so since my layout went live I've been treating the loud buzzing referrred to in the OP as a simple indication of incompetent route-setting. But it now looks as if my Power Cab has been at risk. Prompted by this dicussion,I've now established that a coin test produces the buzzing over the whole layout. And now I'm perhaps realising why the emergency stop feature doesn't work.

 

The layout (my first) takes the form of a "Minories"-style terminus. All the trackwork that matters (8 points and a double-slip,all Peco 75 Electrofrog and operated by Seep PM1s) is concentrated on one board, 5'6'' x 1'6". This board is the point of entry for my Power Cab panel. Electrical wiring takes the form of solid-core (ex-mains cable) for the "bus",with 32/0.2 wiring from the panel to a NCE Auto SW and on to the bus. The droppers are 1/0.6,each to a connector immediately below, with 16/0.2 from there to the bus.

 

As a first attempt from someone with zero electrical knowledge/experience,I've been pleasantly surprised at how well it has all worked. But now it appears that I need to fit some protection. Can any of you kind guys or gals help me to understand exactly what I need and,crucially,how it can now be added to the system? Where does it get wired in - between the panel and the Auto SW,or between the Auto SW and the bus??  (There is no mention of any of this,so far as I can see,in the Power Cab manual)

 

david r

[Ravenser]

a/ I don't use any of the equipment you have, (or even seen it!), so I cant comment here.

b/ Again, I cant help.

 

Not much use - sorry.

 

 

Some comments though,

 

The 1.1 Amps, on the transformer, is the value that the manufacturers have deemed to be safe AND also the value that it can deliver whilst still maintaining a voltage that is within spec for the rest of the circuit. The more amps you pull out of it the less the voltage is available at the terminals!

 

You seem to be wanting to size the circuit breaker to match the transformer/PSU.

You really need to be sizing the circuit breaker to match the load. What gauge are you using, N, 00 or O? Do you ever double head?

Work out your maximum normal current demand and add, say, %10.

 

What you are wanting to do is (dare I say it) another complexity to DCC.

 

 

Finally, I can only suggest you experiment and report your findings.

 

 

Kev.

(Sorry I didn't reply earlier but I was hoping to let someone with more experience to reply first!)

 

 

I'm working in OO and I sometimes run a pair of Hornby 153s  I intend to consist pairs of multiple units where I can

 

My layman's understanding is that if the value of the circuit breaker in amps is higher than the maximum output of the transformer , the breaker won't trip, even if there is a short.  (Hence comments in the past about the "coin test"? I presume this is why NCE state that their own circuit breaker isn't suitable for the PowerCab - ie the PowerCab isn't capable of delivering enough current to trip it? I could be wrong here - electricity isn't something I claim to understand very well.

 

But I don't want to spend £15-£20 on a PSX-1 and find that it does nothing at all because not enough current flows through a short to trip it. £1.49 for a component from Maplins is cheap enough to take a punt... 

[Ravenser]

Yikes!  I came across this thread recently and have been reading it with a growing sense of alarm. In the 2 yrs or so since my layout went live I've been treating the loud buzzing referrred to in the OP as a simple indication of incompetent route-setting. But it now looks as if my Power Cab has been at risk. Prompted by this dicussion,I've now established that a coin test produces the buzzing over the whole layout. And now I'm perhaps realising why the emergency stop feature doesn't work.

 

The layout (my first) takes the form of a "Minories"-style terminus. All the trackwork that matters (8 points and a double-slip,all Peco 75 Electrofrog and operated by Seep PM1s) is concentrated on one board, 5'6'' x 1'6". This board is the point of entry for my Power Cab panel. Electrical wiring takes the form of solid-core (ex-mains cable) for the "bus",with 32/0.2 wiring from the panel to a NCE Auto SW and on to the bus. The droppers are 1/0.6,each to a connector immediately below, with 16/0.2 from there to the bus.

 

As a first attempt from someone with zero electrical knowledge/experience,I've been pleasantly surprised at how well it has all worked. But now it appears that I need to fit some protection. Can any of you kind guys or gals help me to understand exactly what I need and,crucially,how it can now be added to the system? Where does it get wired in - between the panel and the Auto SW,or between the Auto SW and the bus??  (There is no mention of any of this,so far as I can see,in the Power Cab manual)

 

david r

 

 

I'm clear that a circuit breaker(s) should go as far up stream as possible to protect the system. So I'd put one between PowerCab and AutoSW. In theory you could put one on every board, between the connector and the bus, so that only the board with the short dropped out , but in your case that's not really relevant 

 

We seem to have pretty similar layouts , wired in a pretty similar manner