Ballasts for switchstart T5s?

Topics relating to lighting control gear, including magnetic & high frequency ballast and ancilliary devices such as starters, ignitors and switchgear.
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Tom
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Ballasts for switchstart T5s?

Postby Tom » Thu Jan 13, 2011 6:55 pm

In another post dissing HF ballasts, kev_xsi16v mentioned converting a 14w T5 fitting to good old fashioned swsitchstart. We discussed that both 13w T5 and 15 T8 ballasts work with a 549mm 14w T5 tube being under or over driven by just one watt either way. I would be very interested to see the longer T5s working on 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 - The 28w 2D ballast springs to mind with the 1149mm 28w T5 or even a series pair or 14s? I have my doubts on this as 21 inch 13w tubes reject series (S2 etc) starters and continue striking!

I dare anyone with an old 80w ballast (you know who you are!) to try firing up the biggest T5, the HO 1449mm 80w on 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! I look forward to seeing the result! Meanwhile, any suggestions on ballasts for the rest of the T5 range?
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SuperSix
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Re: Ballasts for switchstart T5s?

Postby SuperSix » Thu Jan 13, 2011 8:08 pm

Well in theory it should work for some, the trouble is finding suitable ballasts. The arc voltage and current is different for the different sized tubes even if they're the same wattage like the 2ft 40W runs at 0.88A with an arc voltage of 47V whereas the 4ft 40W runs at 0.43A with an arc voltage of 107. This makes to two completely incompatible with each other's ballast.

The 5ft 80W T5 runs at 0.55A whereas the 5ft 80W T12 runs at 0.88A so the T5 would be overdriven on the T12 ballast. There's also the problem with the very high arc/tube voltages of the T5 HE and HO tubes which means most of the longer or lower current tubes (the ones with high tube voltages) will fail to start with 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 circuit. That's why the 8ft 85W was never used on 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 circuits, the tube voltage was too high.

Some sort of switchless start circuit would be better like SRS but the starting voltage is probably too high for them to work with any existing SRS ballasts.

I don't know what could be done!

Edit:

Hang on a minute, forgot electronic starters, that might stand a better chance of working! I know Transtar make an electronic start ballast for the 8ft 85W, that might work with the 5ft 80W T5!

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Re: Ballasts for switchstart T5s?

Postby Kev » Fri Jan 14, 2011 5:46 pm

I have a box of Philips Master 80W T5 lamps i can get some to murder??

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Re: Ballasts for switchstart T5s?

Postby Kev » Sat Apr 23, 2011 9:04 pm

Some members on here may of recently seen my pictures on Lighting Gallery of the T5 80W HO working on Switch start control gear. Well latest news is that i am ALMOST there with this. Today i got one working normally with pulse starter 75W Ballast and a 8.4 Mf shunt capacitor! Only thing is that the lamp was greatly over powered and the ballast got hot. I have ordered a Transtar K85E to see if this will run the lam properly as suggested by Eliot! I don't mind murdering a few ballasts and 80W lamps to find a magnetic solution to the T5 tube!

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Tom
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Re: Ballasts for switchstart T5s?

Postby Tom » Tue May 03, 2011 10:52 am

80w T5s on Transtar K85E ballasts! Just think of the street lights that could be conceived around this combination!! You could have a very sleek, sexy 3 tube lantern with the ballasts at the base of the column and all the reliability of magnetic! Just wondering how long the lamps would last on this ballast... According to Transtar's website, they're still making them! :D
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Re: Ballasts for switchstart T5s?

Postby Kev » Tue May 03, 2011 9:21 pm

HI Tom these are on the bay i would STRONGLY recomend getting a few! I have got 2 and maybe going for 2 more! Problem is that if a new fitting was designed it would probably be made of cast ally powder coated crap what would fall off after a couple years! lol


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