Problem with NCE Power Cab and PSX

[GWR_NZ]

Hi,

Hoping someone can help.

 

I have a set-up with a NCE Power Cab and a PSX circuit breaker. When I power up - the system starts up with no issues. I can leave the system powered up for as long as I like. I can run a loco but intermittently the PSX will trip - an example of this stopping the loco and changing direction. As far as I can tell I've set the PSX up correctly by changing the CV. I've attached a RRAmpMeter to check the voltage and amperage - all good with a voltage reading of @  13.8 Volts and 0.45 Amps when running a loco (around 0.34 Amps when idle). From this I can conclude that I am not going over amperage. If I bypass the PSX - all works OK - no issues. When the PSX trips the Power Cab does NOT reboot or restart. I've set-up the push button to reset the PSX which works fine. I can reset the PSX, but the PSX will trip intermittently soon afterwards.

 

One curious thing I did notice that if I try to program a loco on the main, the Power cab reports a short (yet I can program a loco fine by bypassing the PSX). 

 

This is a similar fault - but the there is no resolution or the OP didn't report back....

 

http://www.rmweb.co.uk/community/index.php?/topic/50899-interesting-problem-with-a-psx-1-circuit-breaker/

 

This has been tried with two different loco's (one Hornby and one Bachmann) so I can be reasonably confident that it is not the loco. There are a couple of Frog Juicers in the mix a well.

 

Any help or ideas much appreciated.

 

 

[Suzie]

The PSX is most likely detecting the short circuit that occurs when the train comes up against a frog set for the wrong direction. Two things to try:-

 

1. Reduce the sensitivity of the PSX if you can, but this may just move the problem along to the Powercab.

 

2. Use fatter wire to ensure that the overloads are detected much quicker.

 

(3. Replace the frog juicers with traditional frog switching).

 

When you have devices like the frog juicers and auto-reversers you are creating big currents in the region of tens of amps for a short period and you need to have really good wiring to handle it. If the wiring is a bit lacking in size it will take longer for the currents to build up to a point when they are detected (by the device that is supposed to detect them - the juicer) and the current may reduce the available voltage to the juicer to the extent that it does not switch at all leaving the short to propagate to the PSX. If using juicers you really need to be using 2.5mm² wire for your bus all the way including to your juicers, and use fatter than normal droppers to the frogs perhaps 24/2 but at least 16/02.

[BromsMods]

Just a couple of quick questions:

 

1) is your PSX using software revision K or later?

2) have you EITHER installed a jumper between J6-1 and J6-2 OR set CV49=1?

3) how many other locos were on the main when you tried to program a loco?

[GWR_NZ]

Just a couple of quick questions:

 

1) is your PSX using software revision K or later?

2) have you EITHER installed a jumper between J6-1 and J6-2 OR set CV49=1?

3) how many other locos were on the main when you tried to program a loco?

 

Hi BromsMods,

As far as I am aware it is using K or later ( I'll double check in the next day or so - being in NZ  it's now time to go to bed). I've programmed CV49 (I think / hope). Only one loco on the track. 

[GWR_NZ]

The PSX is most likely detecting the short circuit that occurs when the train comes up against a frog set for the wrong direction. Two things to try:-

 

1. Reduce the sensitivity of the PSX if you can, but this may just move the problem along to the Powercab.

 

2. Use fatter wire to ensure that the overloads are detected much quicker.

 

(3. Replace the frog juicers with traditional frog switching).

 

When you have devices like the frog juicers and auto-reversers you are creating big currents in the region of tens of amps for a short period and you need to have really good wiring to handle it. If the wiring is a bit lacking in size it will take longer for the currents to build up to a point when they are detected (by the device that is supposed to detect them - the juicer) and the current may reduce the available voltage to the juicer to the extent that it does not switch at all leaving the short to propagate to the PSX. If using juicers you really need to be using 2.5mm² wire for your bus all the way including to your juicers, and use fatter than normal droppers to the frogs perhaps 24/2 but at least 16/02.

 

In my testing when I removed the PSX two frog juicers were still active. When I get time I'll remove all frog juicers by removing  power and retest but it may not be done until next weekend. Thanks for the suggestions.

[RFS]

Have a look at this article regarding PSX and frog juicers - http://www.sbs4dcc.com/tutorialstipstricks/psxandfrogjuicersshortcircuitconflict.html

[BromsMods]

The note about CV settings to negate auto reversers/frog juicers clashing with the PSX is in the PSX manual - page 4 under Section B User Guidelines.  By default the short circuit detection delay is set in CV65 to 128.  I would suggest setting CV65 to 160 first to see if this solves the problem.  If not, increase the value of CV65 in increments of 8 until the two devices work happily together.  If the value of 160 does work then trying reducing the value of CV65 (again in increments of 8) until the clash re-occurs, then add 8 to that value.  Hopefully this will solve the problem.

Edited September 16, 2018 by BromsMods

[Crosland]

 I can run a loco but intermittently the PSX will trip - an example of this stopping the loco and changing direction.

 

If this is happening on straight track then the frog juicers are not the issue.

[NIK]

Hi,

 

Do your locos have sound or stay alive fitted?.

 

I only asked as you said one of the times the PS-X trips is when the loco is brought to a stop and reversed. When a loco is moving slowly the pickups become critical and if there is a large capacitance inside/attached to the DCC decoder there can be large currents drawn for short periods. This is exactly what the PS-X is looking for to trigger on.

 

As others have said adjusting the trigger period may cure the problem.

 

Alternatively it could just be an intermittent partial short in the wiring or track exacerbated by the track voltage rising slightly such as when locos come to a halt (too low a current or for too short in duration for the Power Cab to trip but high enough and long enough for the PS-X set on 1.27 Amps and a fast trigger to trip).

 

If you were getting enough shorts to fit a PS-X then there is probably a problem with the pre-existing layout.

 

 

Regards

 

Nick

[GWR_NZ]

Hi,

Bit more experimentation today. Disabled all the frog juicers. No change - so rules them out. As suggested above I actually read the manual and I am now suitably embarrassed as changing the value of CV55 to one, then adjusting CV65 to 128 has cured the problem without the frog juicers enabled - will enable and experiment some more.

 

From many years ago, in my computer geek days - RTFM.

 

Thanks for your advice. Much appreciated.

Edited September 22, 2018 by GWR_NZ