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GEC Geographical

Unread postPosted: Sun Nov 1, 2015 8:54 pm
by Matt_p
Hi all, this is my first post, forgive me if it's in the wrong section!

I am midway through building a mini GEC geographical (kings cross vintage)

What I am really after is if anyone can offer advice and equipment (specifically magnetic stick relays and sets)

In a nut shell as it stands it has a three controlled signals, main and sub, two ground signals, a double ended set of points, a limit of shunt and an auto exit. It's got a PC based nx control and indication panel with combined track simulation. The points (101), main (666) and one gpl (201) are 'real' assets.

The project is some what backward in that the interlocking, free wiring and 'location' are built and 'commissioned' but missing the actual interlocking cabling and crucial relays if that makes sense.

If anyone can offer advice I would be grateful.

When I master the forum I will upload designs and photos.

Thanks in advance

Re: GEC Geographical

Unread postPosted: Sun Nov 1, 2015 10:12 pm
by S&TEngineer
Hi Matt and welcome to the forum. We have moved your topic from Signalling Current to S&T Department as its more relevant there.

A starting point would be to see your track and signalling layout so we can understand how you are trying to fit it together. If you have any difficulty in posting such detail then please PM the site administrator or one of the moderators and they will try to assist.

Re: GEC Geographical

Unread postPosted: Wed Nov 4, 2015 4:53 am
by Mad Mac
One or two of us are familiar with said system and would be delighted to offer advice!

Re: GEC Geographical

Unread postPosted: Tue Nov 10, 2015 7:55 am
by Matt_p
thanks for the offer Mad Mac, fingers crossed the interlocking is going to be sufficiently 'simple' that it should be fairly easy...! the trouble I've got is that i am missing crucial 'GEC' relays such as double wound twins and magnetic sticks. in my points set I've bodged the set wiring to accommodate a traditional QL1 011 relay, i am a bit loathed to do any more of these bodges as it somewhat detracts from the point of geographical.

my other dilemma is whether to adjust internal set wiring to match my design, for instance there are two one class exits in the layout (LOS and a main) a 1023 set is used, this can cater for two classes, could i or should i manipulate the set to be a one class exit, thus saving me a relay and or build time. (forgot to mention a 1023 is one of my missing sets!)


Re: GEC Geographical

Unread postPosted: Wed Jan 27, 2016 9:02 pm
by Matt_p
Evening all.
Jubilee junction has come on leaps and bounds since November.
Here is the current status and a few of the issues that I've encountered;
All sets are now installed (care of industry friends!)
Panel is installed (pc simulator)
Trackside equipment and simulation is installed
Entrance and exit ring fully installed and functioning
Geographical cables installed and 'functioning'
One routes worth of aspect cables are installed

Here are the problems thus far;
When setting a route all stages appear in order, entrance registered, exit available, main exit registered, route sets, usrs and nlr down. But after a delay the rug is pulled from under it and the route releases, nlr re picks, another shirt delay then the CCS normalises?

It is a little baffling to be honest, I am putting it down to parts of circuitry missing between sets?

Once this is rectified does anyone know of where the out going hr circuit could be and the outgoing pl for a signal with a main and sub?

If anyone can offer any help or advice I would be more than grateful.
Thanks in advance

Re: GEC Geographical

Unread postPosted: Thu Jan 28, 2016 8:44 am
by ex Probationer
Morning Matt,

If I'm honest, it's been over 25 years ago since I was a TO and faulted GEC Geographical, but I'll have a stab at what might be wrong based on what you've posted so far.

To recap, Selection Level appears OK, and a Route Class is registered in the Entrance Set (MAR picking) as Locking Level is leaving it and returning to it.

In the Entance Set, once the NLR is unlatched the ULCR picks. As soon as the ULCR picks we have finished with route selection and the CCS can normalise.

What needs to happen in the Entrance Set is to maintain the Route Class (MAR initially picked by Selection Level) before the CCS begins to normalise. The MAR needs to be a double wound coil (it picks on one coil and holds on the other). This may be the problem if you have not been able to source any double wound relays. If NOT held, once you lose Selection Level the MAR drops, then you lose Locking Level.

The Aspect Level relays are in the Entrance set so the HR should feed out over the GR energised.

I'll have to get my Geographical course notes out of the loft if there's still a problem or you need to know much else!

Re: GEC Geographical

Unread postPosted: Thu Jan 28, 2016 1:27 pm
by Mad Mac
Ran into this one some 30+ years ago, and it was a single-wound relay in where a double-wound should have been. As Ex says, the whole route "collapses".

Re: GEC Geographical

Unread postPosted: Wed Feb 3, 2016 6:55 pm
by Matt_p
Evening gents.
I've made a little progress with route setting.
It appears that I am losing my nsr, which kills the ulcr.
The problem I thought I had with 056 was not a problem.
So a little progress but not much.
Other bonus points points call, swing and detect properly via the key and can also be called by route.
Forgot to mention I strapped out the nsr front contact in the ulcr circuit, this kept the ulcr up.

Could anyone tell me if the enr and nsr should remain up with a set route?
Sorry if this is a babble.


Re: GEC Geographical

Unread postPosted: Thu Feb 4, 2016 8:41 am
by ex Probationer
In the Entrance Set, NR picks when the entrance button is pressed ((F) contact-Made when button pressed), NSR should then pick and hold over the entrance button((FM) contact-Breaks when button pulled). ENR should then pick (prevents all other ENRs from operating). The ENR provides a hold path to NSR while the route selection sets (the entrance button no longer needs to be pressed) and ULCR provides the hold path once Locking Level completes. Pulling the button drops the NSR and causes Locking Level to be interupted as ULCR drops out.(I think this is the NSR contact you have strapped out, so I'm guessing the route cannot be destroyed)

Probably, strapping contacts out may only confuse your problems further. You say the NSR contact strapped out is holding the ULCR - is this contact high resistance?

But what if the problem is that NSR is dropping out because its hold contact over ULCR is high resistance!

Hope this helps,

Re: GEC Geographical

Unread postPosted: Thu Feb 4, 2016 9:04 pm
by Matt_p
Hi Kevin,
thanks for the detail, i missed a wire off!
the ulcr hold path in the NSR circuit was missing, i had relays off, straps inside the set, then looked closely at the diagram and saw a wire in the design but not on the set!
this is what happens when you play designer, installer and tester! a recipe for disaster, thankfully its only for fun!

this evening we managed to get the 1, 3, 4 aspect levels working, but the signal only managed a single yellow, it turns out that there are more wires missing between a plug coupler and the out going links! (HHR and DR both picked in the entrance.)

on a side note, i am designing the connections in a unconventional manner;
N & X rings have all been designed and installed in the traditional manner (there is no other way?)
geographical cables have been designed and installed in route order and presented in a tabular format, in 'normal' installations core geographical cables (between SEUs) are numbered (G1, G2 etc) then the sub cables (between different sets of the SEU) are numbered G1a, G1b etc) as i've designed by route, each geographical cable is numbered concurrently.
i've adopted the same approach for the aspect cables, does this sound like a sensible approach?

when i master the forum i will post PDFs of the designs so far.


Re: GEC Geographical

Unread postPosted: Fri Feb 5, 2016 2:46 am
by Mad Mac
Aspect cables followed the same "principle" (A1 etc), so you're on the right lines.

Re: GEC Geographical

Unread postPosted: Tue Mar 1, 2016 11:18 pm
by zapiy
Cracking work chap, would love to see how this turns out, used to love faulting this stuff at Bletchley PSB..

Re: GEC Geographical

Unread postPosted: Sun Mar 6, 2016 9:11 pm
by PSB Supervisor
zapiy wrote:Cracking work chap, would love to see how this turns out, used to love faulting this stuff at Bletchley PSB..
Hi, apologies for being off-topic but I worked at Bletchley PSB in the 80's - best place I ever worked.

Re: GEC Geographical

Unread postPosted: Tue Jun 7, 2016 9:54 am
by Matt_p
It’s been an awful long time since my last post apologies!

For all intents and purposes the interlocking is fully functioning, all routes set (and stay set) and all signals clear.

Now the big question comes – what do I do with it?
The aim was to have a working interlocking to demonstrate signalling principles on and aid staff with passing IRSE exams, with hindsight a simple RRI would have been better.
I am also leaving my current role and no matter how hard I try I cannot fit the interlocking into a cardboard box (plus my wife wouldn’t be too impressed if I took it home!)

So, does anyone have any suggestions for its fate (providing my employer will ‘release’ it?)