Author Topic: Low cost electrical cable?  (Read 1991 times)

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Offline John Candy

Low cost electrical cable?
« on: October 30, 2013, 08:47:33 AM »
I have just carried out a "guesstimate" of the amount of cabling needed for the point motors and signals.
It looks as though it could add up to as much as one mile of single core.

Have done some "Googling" and the best price I have so far come up with is 100 metres of single core with spec. as below for 14.99GBP (from http://www.microminiatures.co.uk/ ).

Anyone know of a better option or have any comments on the spec. bearing in mind it is to power LGB point motors via a CDU (capacitor discharge unit)?

Rating: 3.0 A @ 1,000V RMS max
O/D: 1.6 mm nominal
Wall cover: PVC 0.3mm to DEF61-12 type 2.
Core: Stranded, 16 x 0.2 mm tinned copper conductor
Weight of reel approx 700 gm


Regards,
John.
My fellow Members, ask not what your Society can do for you, ask what you can do for your Society.

Offline Andy B

Re: Low cost electrical cable?
« Reply #1 on: October 30, 2013, 11:44:27 AM »
John,

What is the longest cable run you expect to have, and what will be the worst case voltage / current requirement of the device at the end?
Just thinking about voltage drop, and therefore cable size.

If you have an electrical supplier near you who supplies the trade, it would be worth asking for a price on 1000m of a single core conduit cable.

Andy

Offline 454

Re: Low cost electrical cable?
« Reply #2 on: October 30, 2013, 12:43:32 PM »
John,
If you are using LGB point motors & they are the 2 terminal EPL type then they operate using a two wire ac current.
The direction of which rotates the motor one way or the opposite way using control diodes. So, in my setup I have never used cap discharge units since I chucked away my old H&M & Peco & SMP point motors which used the slam/slam solenoid principle on smaller scale layouts, when a CDU becomes the preferred solution.

Why not use a RC system & remote power packs powered by solar cells? If so much wiring is to be considered, then an alternative technology may be advantageous. This could quite reasonably be achieved with LGB EPL units. The interfacing of which may need due consideration.

I am sure the later DCC units deal with all of this quite adequately within their repertoire of operating capability. I am sure that would be worthy of consideration for such a large system.

Dave
454

Offline Andy B

Re: Low cost electrical cable?
« Reply #3 on: October 30, 2013, 03:16:28 PM »
Dave,

Use of DCC did cross my mind.
One thought, having read the article in the latest newsletter regarding the choice of system used on 'St Ives' - is that DCC generally uses a text-based display.
How user-friendly is that going to be given that John's line is outdoors, and that (I assume) he'd like visitors to be able to run the line without a 3-hour training session first, to understand how the signals and points are numbered, interlocked, operated, etc?
Of course, this may be doing DCC systems a great dis-service based on my very minimal knowledge of them...

R/C with solar cells sounds good - is there a proven off-the-shelf solution?

Andy

Offline cabbage

Re: Low cost electrical cable?
« Reply #4 on: October 30, 2013, 03:42:05 PM »
John,

Given the time that it is likely to be out there, I would go for a single core rather than a stranded cable...

Farnell flog 100m reels of 1x0.8mm cable for about £12 dropping to £47 for a 500m reel. This all single core stuff so you would need two lengths. Where are you going to position your CD units in relation to the points motors? And how do you intend to trigger the CD units themselves?

Offline 454

Re: Low cost electrical cable?
« Reply #5 on: October 30, 2013, 10:13:39 PM »
The only major snag with DCC as I see it is that dependant on the installation & it's complexity the cost can mount quite considerably.

Although not DCC on Timpdon Electronics website there are some R/C control solutions for points, signals & accessories interfacing to the more well known point motors including LGB type & also those using regular RC servos.

From a weatherproofing viewpoint the modules may be hidden in lineside buildings and/or weatherproof plastic instro boxes with cable gland cable entry/exit local to the units needing to be controlled.

Not sure that CD units are an appropriate switch machine driver in the great outdoors, for this I remain a sceptic.

When multiple switches need to be cascaded for route selection this is where I believe they will let the system down.
Decision has to be made how many switches might a CD unit drive in parallel at one time. Then translate this to outside in all weathers. The unreliability could be quite frustrating. Hope I'm wrong in this estimation.

Another alternative :
I have seen pneumatic control with a compressor & micro bore piping & this is quite effective. The compressor though can be quite off-putting when trying to carry out a conversation.

Back to electrical cable & conventional wiring:
Once the control circuits are designed for "conventional" wiring & everything covered that needs activation is connected then you will be amazed just how much wire is actually required. The resultant spaghetti can be quite daunting. Corrosion on terminal connections must be considered when designing for reliability.

This is why I thought that a RC solution might be an alternative solution.

Dave
454



 

Offline Peaky 556

Re: Low cost electrical cable?
« Reply #6 on: October 31, 2013, 01:07:19 PM »
John, have you thought of using the rails as one conductor, namely an 'earth return' for all of the signals, points etc?  I'm assuming you are not wiring the track for loco pickup, in which case all of your rail joints would need to be bonded and some attention to the points.  I would make both rails connected at same earth potential to maximise your chances of the signals getting through.  The advantage of course is less wiring!
Regards, Tim

Offline John Candy

Re: Low cost electrical cable?
« Reply #7 on: October 31, 2013, 08:32:02 PM »
Thanks for all the replies and suggestions.
I am anxious to avoid anything which is susceptible to damp/corrosion or will require excessive maintenance.
Another concern is rodents........a family of squirrels spend a lot of time in the garden and the inevitable rats are seen occasionally (there are farm buildings less than 100 yards away).
Has anyone suffered rodent damage to cables/track, etc.?

COMMON RETURN : Had been mulling over that one but not keen on all the rail bonding required although not ruled out.

DCC : Never really taken much interest in this since I had viewed it as an indoor/smaller scale gimmick but I assume it involves some form of multiplexing? Suppose I could use a constant AC supply to the LGB motors (a kind of "ring main" which would substantially reduce cable requirements) and send a control signal through the track using MUX / DEMUX units? Again this would involve rail bonding but the cable requirement would be drastically reduced.

PNEUMATIC : I already have sufficient equipment to operate eleven turnouts using Sunset Valley RR materials bought from Back2Bay6 (in conjunction with my rather noisy Draper 2.5HP 25 Litre compressor). The cost is more than twice that of LGB per "switch" so is rather expensive.

CDU : Would want to be able to control at least two motors simultaneously (e.g. setting crossovers and slips).
On the "Gaugemaster" website, an instruction sheet for wiring a power unit for LGB point motors, recommends using a CDU,.
On the other hand, I read this http://www.barnarailway.com/control_and_wiring.htm where it is suggested that 12V is sufficient for LGB point motors.
Another site recommends a 25V AC supply http://www.trainweb.org/girr/tips/tips1/lgb_1600.html

As Andy suggests, I would want a control panel which would be in a familiar/traditional format, so that visitors would understand it without too much explanation (and this old codger does not get too confused by all the buttons on a DCC hand held unit when having a "senior moment")!!!

Regards,
John.
My fellow Members, ask not what your Society can do for you, ask what you can do for your Society.