Electrical supply to signals

[Stuart-h]

Does any 1 know what the voltage is on a standard over ground 3 & 4 aspect signal and the signals thats are in sideings at all?

 

[TOCDriver]

Does any 1 know what the voltage is on a standard over ground 3 & 4 aspect signal and the signals thats are in sideings at all?

I think you'll find that many urban signals are powered directly from the mains.

 

[t o m]

For an SL35 lamp you have an input of 110V which is transformed down in the signal head to around 12V for the lamp operation.

 

[John Webb]

The SL35 signal lamps are 12 volt 24 Watt lamps. As tom says, the feed to the signal heads is at around 100 volts AC, and each aspect has it's own transformer. Taps on the transformer allow the bulb voltage to be adjusted - usually to around 10.5 to 11 V so that the bulb is under-run slightly to give a longer life.

The one Ground Position Light signal I've handled was fitted with 110 Volt bulbs.

 

[t o m]

Most signal lamps have now been replaced with the infamous LED light engine conversions.

I think you'll find that many urban signals are powered directly from the mains.

I disagree with this. The railway prefers to use it's own power supply. In remote areas batteries are used or rarely a mains supply if there is no other option.

 

[broadgage]

The railway does indeed prefer to use its own supply for signalling where possible, this is not actually generated by the railway but is obtained from the grid. The signalling power supply should be much more reliable than a normal grid supply since it is usual to provide either duplicate feeds from two grid areas, or a single feed and a generator.

The signalling power supply is normally distributed at a relatively high voltage, 660 or 720 volts being popular. At the point of use this is transformed down to a lower voltage, often 110 volts.
Individual bulbs in signals are usually 12 volts, as posted above, with a transformer for each bulb.

 

[Joseph_Locke]

The railway does indeed prefer to use its own supply for signalling where possible, this is not actually generated by the railway but is obtained from the grid. The signalling power supply should be much more reliable than a normal grid supply since it is usual to provide either duplicate feeds from two grid areas, or a single feed and a generator.

The signalling power supply is normally distributed at a relatively high voltage, 660 or 720 volts being popular. At the point of use this is transformed down to a lower voltage, often 110 volts.
Individual bulbs in signals are usually 12 volts, as posted above, with a transformer for each bulb.

The signalling 650V can also be derived from the 25kV traction supply, which in turn can be fed from alternative grid feeders.

Most signalling supply points (SSP) in non-OLE areas have a single distribution network operator (DNO) supply, the option to feed it from another SSP and a UPS or UPS and standby generator.

The new ROCs have generators, UPS and twin DNO supplies, independent of HVAC and domestics ...

 

[Crossforth]

Most signal lamps have now been replaced with the infamous LED light engine conversions.

Those bloody light engines... granted, it means less work, but when they black out... oh boy

 

[t o m]

Those bloody light engines... granted, it means less work, but when they black out... oh boy

We find they tend not to draw enough current to keep the ECR picked.

 

[Crossforth]

That's what we find. We do have a couple, as a trial, that have the ECR strapped out but I don't know whether we are getting funding to strap all of them out. We have had a few though where they just black out :/ usually in SSI areas

 

[Signal Head]

That's what we find. We do have a couple, as a trial, that have the ECR strapped out but I don't know whether we are getting funding to strap all of them out. We have had a few though where they just black out :/ usually in SSI areas

That seems a bit rum! Do you mean the signal isn't being proved lit in the signal in rear? I'm surprised that's been authorised, unless it's on, for instance, a terminal station platform starter with nothing reading up to it.

They're quite widespread now, I've noticed them around Manchester, on various ECML locations, and around London Bridge. I only know of the ones manufactured by Howells, are these the ones you are having trouble with?

 

[455driver]

The signals where the bulb has been replaced with an LED cluster are fine because the beam is still focused by the lens, the ones where its just a cluster of LEDs (all in one aspect or seperate) are fu fu fulippin awful, they are blinding in the dark and next to useless in fog where the beam cant 'cut through'. But what do I know, I just drive past them everyday with my eyes shut in the dark and straining to see them in the fog!

As for those cheap and nasty VFM? signals, no comment!

 

[Signal Head]

The signals where the bulb has been replaced with an LED cluster are fine because the beam is still focused by the lens, the ones where its just a cluster of LEDs (all in one aspect or seperate) are fu fu fulippin awful, they are blinding in the dark and next to useless in fog where the beam cant 'cut through'. But what do I know, I just drive past them everyday with my eyes shut in the dark and straining to see them in the fog!

As for those cheap and nasty VFM? signals, no comment!

Do you mean VMS? (lightweight 'flat panel' type?) I was under the impression that 'the Southern' wouldn't have anything to do with them. They were apparently considered for the new London Bridge/Thameslink signalling but rejected in favour of a more traditional LED type (and writing 'traditional' and 'LED' together doesn't look right, they're still new-fangled to me!).

I heard the same complaints you raise, but specifically about those, ie there is so much light that with several on a gantry you cannot tell which is yours until you're more or less on top of it, especially in misty or foggy conditions.

 

[455driver]

Do you mean VMS? (lightweight 'flat panel' type?) I was under the impression that 'the Southern' wouldn't have anything to do with them. They were apparently considered for the new London Bridge/Thameslink signalling but rejected in favour of a more traditional LED type (and writing 'traditional' and 'LED' together doesn't look right, they're still new-fangled to me!).

I heard the same complaints you raise, but specifically about those, ie there is so much light that with several on a gantry you cannot tell which is yours until you're more or less on top of it, especially in misty or foggy conditions.

Yes VMS are the ones, they have been used on the Salisbury to Exeter resignalling which is where I see them (not as a driver thankfully).
They have lots of small LEDs arranged in odd patterns but no hood, when it snows it will congregate on the small lip in front of each LED and because there is no heat from the LEDs it wont melt, end result signal wont be able to be seen and likely to be SPADded which of course will be the drivers fault, excellent design, not! :roll:

The best ones are the LED enhanced conventional/traditional head, nice clear colours, well seperated and good penetration without blinding the drivers, which is why they will be replaced with those silly 'all in one' signals. :roll:

 

[Joseph_Locke]

The best ones are the LED enhanced conventional/traditional head, nice clear colours, well seperated and good penetration without blinding the drivers, which is why they will be replaced with those silly 'all in one' signals. :roll:

Do you mean the dichroic "optic diode" jobbies (as seen around Stockport-Wilmslow)? Those are more like the old searchlight types in that they show all three colours through one aperture, with a second yellow-only aperture if required. They are a single light source with dichroic filters to make the colours. Shame it took Ansaldo a year to get the colours right.

 

[455driver]

No, its basically the normal (old) signal head (with 2, 3 or 4 seperate lens) and they just replace the bulb at the back with an LED pack, it looks just like a normal signal (which it is, complete with rusty bits) but the colours are more defined especially the green which is very green instead of bluey green.

 

[t o m]

the colours are more defined especially the green which is very green instead of bluey green.

This is because a conventional lamp gives off a yellowish light, therefore green aspect lenses are actually blue - blue and yellow makes green. The lamps were replaced with LEDs, which can display white light and would thus cause a blue aspect, so a coloured LED is used to get the right sort of green.

 

[Crossforth]

That seems a bit rum! Do you mean the signal isn't being proved lit in the signal in rear? I'm surprised that's been authorised, unless it's on, for instance, a terminal station platform starter with nothing reading up to it.

They're quite widespread now, I've noticed them around Manchester, on various ECML locations, and around London Bridge. I only know of the ones manufactured by Howells, are these the ones you are having trouble with?

Apologies. I think I meant the EKR

 

[455driver]

This is because a conventional lamp gives off a yellowish light, therefore green aspect lenses are actually blue - blue and yellow makes green. The lamps were replaced with LEDs, which can display white light and would thus cause a blue aspect, so a coloured LED is used to get the right sort of green.

Thanks for the explanation but I guessed they were using yellowy LED packs for the reasons you state.

A year or so ago a colleague had just returned to work after having a few months off with a 'bump' on the head (he was actually lucky to survive) and he noticed the greener greens and was worried that the bump had changed his colour perception but after having a quiet chat with a few other drivers he was relieved to find out it was the lamp replaced by LED packs that he was referring to.

 

[Railsigns]

Do you mean the dichroic "optic diode" jobbies (as seen around Stockport-Wilmslow)? Those are more like the old searchlight types in that they show all three colours through one aperture, with a second yellow-only aperture if required.

Those signals always have two apertures, even if the signal only needs to display three or two aspects. Both apertures are equipped to show an equal number of colours; this is because single-filament lamps are used and the lamp in the other aperture is a stand-by if the main one fails. In contrast to a traditional four-aspect searchlight signal (and the modern LED equivalent), the green aspect is normally displayed in the upper aperture.

They are a single light source with dichroic filters to make the colours.

No - behind each aperture there are separate light sources (lamps) for each colour. The lamps are set at right angles to each other and the mirrors direct the light out towards the front.

 

[Signal Head]

Apologies. I think I meant the EKR

That's makes a bit more sense, however, according to the Howells website, they provide a 'dummy' ER to put in place of the original relay, to maintain the connections, although they also state that the engine itself draws enough current to energise the relay.

 

[Crossforth]

That's makes a bit more sense, however, according to the Howells website, they provide a 'dummy' ER to put in place of the original relay, to maintain the connections, although they also state that the engine itself draws enough current to energise the relay.

It's only the odd few that seem to not work so we'll see what happens.

 

[noddingdonkey]

Surely the answer to the original question is 25,000 volts. At least if any wannabe cable thieves are reading, that's the answer.

 

[Markos72]

Almost all of our signals on the E&G (on my patch anyway) are long life SL35's.
No prospect of them being changed to LED's any time in the future.