Author Topic: Questions about Philips TL-M RS fluorescent tubes  (Read 365 times)
WorldwideHIDCollectorUSA
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Questions about Philips TL-M RS fluorescent tubes « on: July 18, 2021, 06:14:05 PM » Author: WorldwideHIDCollectorUSA
So far, I currently have a limited understanding of how Philips' TL-M RS fluorescent tubes work. From what I understand, they use a magnetic strip to help assist with starting. I am wondering if they need special ballasts or could they be operated on standard preheat ballasts using starters? Any information about these lamps would be appreciated.
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Re: Questions about Philips TL-M RS fluorescent tubes « Reply #1 on: July 18, 2021, 08:19:15 PM » Author: dischargecraze
Hey,

From what I know as I own a couple of these bulbs, they were designed to light in harsh conditions (low temperatures and humid environments), and can be used with preheat ballasts. You can use the lamp with a starter, or you can take the starter out of the fixture and it will still light.

Tom
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Medved
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Re: Questions about Philips TL-M RS fluorescent tubes « Reply #2 on: July 19, 2021, 01:03:53 AM » Author: Medved
It is not magnetic, but electrically conductive strip.
It is there to form a defined potential external electrode, not affected by e.g. humidity (because the strip is just way more conductive than any moist mess on the tube surface) to ensure reliable starts even when the tube is contaminated.
It is designed to work on ballasts like SRS, where is no starter, nor any significant voltage boost for ignition.
But it works on stsrter preheat as good as any other lamp. Only the preheats were not preffered for that service, because the starter contacts formed system failure point (they are not heated by the lamp, so stay humid during operation and so corrode).
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James
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Re: Questions about Philips TL-M RS fluorescent tubes « Reply #3 on: July 19, 2021, 05:31:17 PM » Author: James
If you measure the striking voltage of a T12 argon lamp as a function of relative humidity, there is an interesting phenomenon in which the voltage is lowest at either very low or very high humidity.  Unfortunately, in the range of typical humidities present in most normal weather conditions, the striking voltage is near to the maximum.  There are two ways this can be overcome - either to make the glass tube of the lamp as non-conductive as possible, or as conductive as possible.  By far the majority of T12 lamps choose the former option, which is achieved by coating the glass with a silicone fluid that breaks up moisture droplets to achieve maximum electrical resistance.  The TL-M lamps took the opposite direction, to make the glass as conductive as possible thanks to the external stripe of a copper-silver alloy burned into the surface of the glass.  In particular at low temperatures the TL-M tends to strike more reliably than the ordinary siliconed T12 tubes.  It is also more reliable under dimming conditions, with less flicker when dimmed very deeply, and it strikes better on instant start circuits.

Incidentally, unlike the British striped tubes where the metal stripe was connected to both end caps and earthed and its only purpose was to lower the glass resistance, for the TL-M the stripe is actually connected to one electrode.  The connection is made via a 1 megohm resistor, contained inside one of the lamp caps, to avoid the risk of electrocution when touching the stripe.
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Re: Questions about Philips TL-M RS fluorescent tubes « Reply #4 on: July 20, 2021, 12:12:06 AM » Author: Medved
It is abou the "just right amount of moisture" forming a kind of high ohmic resistive layer on the tube surface, which is then acting as a voltage divider, distributing the potential evenly along the tube. So by that minimizing the electrical field strength at any point.
Normally when the tubes are dry, the electrodes are in fact a spiky probes in an empty space, so with most of the voltage drop concentrated just around the electrode surface. When the tube surface is grounded (small area like strip is enough; if the conductivity of the dirt is high enough or when there is a deliberate strip or layer embedded in/on the tube wall), it just forms strong field towards the electrode no matter what, so easing the ignition.


I'm wondering: Making the tube surface (at least part of it, like the stripe or so) just conductive (so to form the explicite ignition aid external electrode and act as an electrostatic shield to whatever mess is on the outer surface) seems to me as way more reliable way to eliminate the potential distribution effect than all the attempts to make it nonconductive under all condition. Yet still most makers went to the "attempt for nonconductive surface" way, so what was the motivation? Patents? Some production aspects?
« Last Edit: July 20, 2021, 12:27:05 AM by Medved » Logged

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Re: Questions about Philips TL-M RS fluorescent tubes « Reply #5 on: July 20, 2021, 05:15:01 PM » Author: James
Thanks for the extra details Medved.  I think the answer to your question lies in the cost.  The siliconing process costs almost nothing - at the end of the line the tubes pass over rollers whose undersides are immersed in silicone solution which itself also has low cost.  The metal stripe meanwhile is made from a rather expensive silver-copper alloy and has to be heated to burn it into the glass.  The materials and process are both expensive.  Plus there is the cost of adding a resistor inside each cap and connecting it to one of the base pins with a kind of rivet assembly, and welding the other end to the cap shell.  So the TL-M tubes are used only in conditions where it is really necessary aand customers are willing to pay the relatively high price for those tubes.  Also sometimes you can see that the continually energised metal stripe creates a dark area in the coating over life.  I suspect that this draws mercury ions to the wall with increased force, which then alloy with sodium from the glass to create a dark grey sodium amalgam coating.  So it could also be that the lumen maintenance during life is far worse for TL-M tubes than siliconed tubes.  I have not seen any lumen maintenance curves for TL-M, but did see many old lamps and often they were surprisingly darkened compared to regular T12. 
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Re: Questions about Philips TL-M RS fluorescent tubes « Reply #6 on: July 30, 2021, 06:32:43 AM » Author: monkeyface
Here the most fluorescent lamp streetlights were rapidstart with TL-M tubes. Other indoor installations here with TL-M De Luxe colour tubes were cinema and museum lights with dimming circuits.
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