Haunted model railway?

[Elvinley]

I think Elvinley must be haunted. Some very strange electrical issues have surfaced of late.

This is so bizarre, but I will try to explain:

I have recently purchase a Walthers RS2 for my forthcoming US layout. I have been running it in on Elvinley. I had it sat in a siding with the points against it. No power was applied to the track from my Gaugemaster and the switch for direction was centred. I noticed the headlight was dimly lit. I touched one rail with a screwdriver and the light became brighter. If I touched the rail with a finger again the light became brighter. All this ceased when I disconnected my gaugemaster high frequency track cleaner. Mike (4x2ybecauseican on the forum) has witnessed some other strange electrical happenings on the layout but this is the maddest.

[EtchedPixels]

I think Elvinley must be haunted. Some very strange electrical issues have surfaced of late.

This is so bizarre, but I will try to explain:

I have recently purchase a Walthers RS2 for my forthcoming US layout. I have been running it in on Elvinley. I had it sat in a siding with the points against it. No power was applied to the track from my Gaugemaster and the switch for direction was centred. I noticed the headlight was dimly lit. I touched one rail with a screwdriver and the light became brighter. If I touched the rail with a finger again the light became brighter. All this ceased when I disconnected my gaugemaster high frequency track cleaner. Mike (4x2ybecauseican on the forum) has witnessed some other strange electrical happenings on the layout but this is the maddest.

Not really a surprise - you need very very little current for an LED light to brighten, and a track cleaner is enough to do the trick. I imagine your prodding changed how it interpreted the "dirt" it was seeing.

[Elvinley]

It is strange that any current got to it with the points set against it though. Also the loco doesn't move when it is like this, but the light gets quite bright.

[polo2k]

I would imagine that it has something to do with the HF track cleaner. not really sure how its coming on with the points against it. the brightening will be your capasitance making a difference.

[Elvinley]

I am only touching one rail. The one which is isolated by the point. I also noted that the rear headlight flickers when the loco is run forwards if the HF cleaner is switched on.

[Newportnobby]

I suggest you remove your fingers from the track.
You know what they say - many hands make light work     

[4x2]

Hello Ian ! I'll have to bring my meter next time i come over, it may be possible that the HF cleaner is arcing around the point somewhere but not carrying enough current to effect the motor, but it's enough to light the LED... Don't worry if all else fails - we'll call the Ghostbusters !  

[poliss]

I found this which, I think everyone will agree, explains everything.

"This problem can manifest itself in industry when old motor controls are replaced with new, solid-state electronic motor controls providing greater energy efficiency. Suddenly there may be weird electrical noise being impressed upon signal wiring that never used to be there, because the old controls never generated harmonics, and those high-frequency harmonic voltages and currents tend to inductively and capacitively "couple" better to nearby conductors than any 60 Hz signals from the old controls used to."

[4x2]

I found this which, I think everyone will agree, explains everything.

"This problem can manifest itself in industry when old motor controls are replaced with new, solid-state electronic motor controls providing greater energy efficiency. Suddenly there may be weird electrical noise being impressed upon signal wiring that never used to be there, because the old controls never generated harmonics, and those high-frequency harmonic voltages and currents tend to inductively and capacitively "couple" better to nearby conductors than any 60 Hz signals from the old controls used to."

Hi Poliss ! Are you suggesting that the LED is being powered via inductance - ie it's picking up the AC from the HF cleaner because the rails are close together ? My electrical knowlege is average, so i just want to know if i understood your reply 

[poliss]

I have revised my theory and I think this is what may be happening when the track is touched.
"When the track cleaning system detects dirt (i.e. electrically detects an open circuit) the unit produces an AC output and superimpose it onto the track."
http://freespace.virgin.net/c.gardner/semg/relco.htm

Shame we don't have any qualified electricians on the forum who could say what's really happening. Maybe we should go out and press gang one. 

[Zunnan]

What poliss mentions is entirely plausible, I've encountered inducted voltage in 'dead' cables I've been working on in the past that run in close proximity to buried mains cables. Don't forget that a (insulfrog) point self isolates only one rail, so one rail will still carry the AC of the track cleaner. I would think that its more likely that the isolated rail isn't fully isolating, if the track section is painted or ballasted it can be grounding or earthing which will complete a high resistance circuit that allows sufficient current to flow to light an LED. When you touch the isolated rail it improves the grounding and so the LED becomes brighter. Its known as earth leakage, and its why you should use an RCD for external mains electrics.

Along the lines of haunted model railways, when I was 12 or 13 I had a brief forray into N Gauge with a small American layout. It used Peco streamline track and was literally just a circuit with a long passing loop. One day I tried to run a train and instead of it running, one of the points decided to melt instead; and when I say melt, the tie bar actually melted to the point that it stuck to the baseboard and the sleepers on either side of it went soft!

[Elvinley]

That is utterly bizarre.
Thanks to everyone for the great answers and theories!

[Sprintex]

What poliss mentions is entirely plausible, I've encountered inducted voltage in 'dead' cables I've been working on in the past that run in close proximity to buried mains cables.

And is exactly the reason that telephone cables consist of TWISTED pairs of wires for each line, and also all the pairs in a large cable twist around each other. If all the wires were straight and in line with each other everyone on that cable would be able to overhear others' conversations  


Paul (ex BT engineer)

[Zunnan]

They still can and do when some sloppy git is a bit heavy handed with the solder on the frame, or a paper core cable gets wet. And I have to admit to hating jointing 3200 pair cables when the units are twisting in opposite directions, especially when one of them is an old paper core. I'm sure the cable gangs draw them in the wrong way around on purpose sometimes!

Best one for inductance I've had so far was on an attempted cable theft when the cable was abandoned and coiled in the corner of a field, presumably ready for loading into whatever vehicle they were using to cart it away. I tried to mole the cable to get a length for the renewal as I didn't fancy walking out 800m and back and was alarmed to find 72v between all pairs and earth! I could see both ends of the cable too, the entire thing was out of the ground and not in contact with anything else...it had been coiled on top of a 3 phase 33kv cable buried about 6 feet down that was out of balance.

[MinZaPint]

I'm frightened to turn on the kellle now, good time to move over to Diesels!