IS it possible to convert a SS ballast into SRS?

Topics relating to lighting control gear, including magnetic & high frequency ballast and ancilliary devices such as starters, ignitors and switchgear.
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Liam
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IS it possible to convert a SS ballast into SRS?

Post by Liam » Mon Jul 22, 2013 3:59 pm

Hi guys i was thinking today is it possible to convert a SS ballast into SRS? Now i've tried using 2 ballasts and 2 cap one at 10 uF
and one at 12.5uF and still can't get a flash.

Could some one please tell me if its possible :) :)

Many thanks

Liam

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Re: IS it possible to convert a SS ballast into SRS?

Post by SuperSix » Mon Jul 22, 2013 7:06 pm

I'd say you're probably more likely to blow the tube, or overheat the ballasts. A two part SRS unit is possible, in fact, I think GEC used to make them but it'd be extremely unlikely that a combination of standard available ballasts would do the job!

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Re: IS it possible to convert a SS ballast into SRS?

Post by Bluto » Fri Jul 26, 2013 12:55 am

I once saw an old lamp post , running an 80 watt mercury , using a Crompton 6-ft 85 watt SRS ballast as a choke to run the mercury lamp . This was a "private" , ie , not street lighting dept job , at a community centre car park. The caretaker had done the job himself and , it seemed to be working just fine , and had been for some time. I guess he wasnt aware that ballasts - or chokes - as he called them , (he had some limited electrical knowledge and was used to replacing 4ft 40 watt fluorescent chokes inside the centre) - came in different sizes and types , and assumed that any choke / ballast would do.
He had wired it up in series with the lamp using just the first two terminals (ie the "primary" of the SRS ballast) , so it probably would have been fine left like that . (In its correct application with a fluorescent tube ,the primary of these ballasts does act just like a choke to the lamp once it has started).

SO - an SRS ballast could probably be used as a SS choke (although it probably wouldnt be able to stand the high voltage spikes generated by the starter). I doubt You could make this work the other way round though with seperate ballasts as the SRS ballast is in effect a transformer and the two windings would have to be in the same unit , if that makes sense.


Jeremy

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Re: IS it possible to convert a SS ballast into SRS?

Post by Andy » Fri Jul 26, 2013 7:46 pm

I have a 6ft Thorn PP285 that has two part SRS ballasts which I think is a bit unusual.
There are wiring diagrams on each ballast to show how they relate to each other.

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Re: IS it possible to convert a SS ballast into SRS?

Post by Bluto » Tue Jul 30, 2013 8:25 pm

Andy that sounds like a Quickstart rather than an SRS. I have some old 2ft fittings that were once used in Derbys old bus station like this , and we used to use 2ft quickstarts in some of the public toilets in Derby.
Quickstart uses a choke , pretty much the same as a ballast and starter switch. Upon switch-on, the starter closes and preheats the tube's cathode filaments. Upon opening, the magnetic field within the ballast collapses, causing a voltage pulse which strikes the tube. This is often repeated twice or more, causing the distinctive blinking at startup.">switchstart , and a seperate quickstart transformer instead of a starter switch. Quickstart transformers vary in appearance but often look like a second ballast. The quickstart transfomer has two output windings which keep the lamp cathodes supplied with low voltage and heated all the time. The fitting needs to be well earthed for these to start properly. (We always use metal-strip tubes in the 2ft fittings I mentioned , normal tubes without the metal strip wouldnt always start reliably.)
Liam ,If You could get hold of a Quickstart transformer You could fairly easily convert your ballast and starter switch. Upon switch-on, the starter closes and preheats the tube's cathode filaments. Upon opening, the magnetic field within the ballast collapses, causing a voltage pulse which strikes the tube. This is often repeated twice or more, causing the distinctive blinking at startup.">switchstart to Quickstart , the starting characteristics are similar to SRS .

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Re: IS it possible to convert a SS ballast into SRS?

Post by Andy » Tue Jul 30, 2013 9:05 pm

Hi Jeremy,

I have a couple of quickstart fittings that are as you describe with what look like two ballasts, but I also have twin six foot Thorn Pop Pack which has two sets of two-part SRS ballasts with a wiring diagram on them showing how the two relate to each other. It seems like quite an unusual setup. I don't have any Thorn catalogues but it would be interesting to see if they were listed. I will have to post up a pic but think I have a photo of the fitting somewhere on the gallery.

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Re: IS it possible to convert a SS ballast into SRS?

Post by amtrakuk » Wed Aug 27, 2014 12:58 pm

This is something I'd like to know more of too. I forget who :crying but saw a vid on youtube with 2 x 125 watt ballasts in series but that was a switch start circuit.

Theory time;

I wonder if one ballast can drive the tube and the other be used in series with a capacitor in place of the starter? My thinking is the the tubes resistance will be high when cold and the "starter ballast" will allow just enough current for the cap to work. Once the tube is warmed up the resistance across the tube will have dropped enough for the in-line ballast to restrict the cap enough for it to stop working (therefor open circuit) and the the tube to run as normal.

I have no idea if that setup will work and going on the theory the tube's resistance is different between cold and hot. If it does work then I'd have thought it would give a vivitronic /type/ of start.
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