Platinum Lamps. Questions, queries, wisdom required

partyanimallighting · June 18, 2023

Hi all. I am seeking some knowledge for future reference regarding the Platinum and Sirius series of lamps designed by Philips and Osram and used throughout a wide variety of moving heads available. My question is regarding wattage ratings between lamps and ballasts. Now 5R lamps are rated at 189 watts and 7R lamps at 230 watts which is about a 21% increase in wattage. Yet both lamps (as far as I know and have seen) will function with any equivalent 5R ballast. The same seems to be the norm with the higher wattage lamps, 15R, 16R and 17R, 300 watts to 350 watts. From what I've seen they will function with a ballast rated at 330 watts. Now, from what I recall (I could be wrong but I believe I discussed this in another forum), upon lamp strike, the ballast supplies an extremely high surge to ignite the gases to create the lamp strike and once the lamp strike is successful, that voltage trickles down to somewhere around 80 ~ 90V. In a case like this, would using say......a 300 watt ballast to strike and run a 17R 350 watt lamp put too much load on the ballast and cause premature failure of the ballast? Or the 380V power supply feeding the ballast? Or does the ballast simply supply and stabilize the voltage required by the lamp to function from the 380V power supply which feeds it? In the reverse scenario, would using a 350 watt ballast with a 15R 300 watt lamp cause any kind of catastrophic event? Inquiring minds want to know.

musht · June 20, 2023

On 6/18/2023 at 5:18 AM, partyanimallighting said:

the ballast simply supply and stabilize the voltage required

No where near an expert in discharge lamps, but remember 2 main variables.

Voltage and Current, need the ignitor Kilo Volt strike pulse to get the arc struck, after that the ballast is limiting the Current to keep the arc stable and not melting the electrodes, Voltage is a function of keeping the Current stable,not the end product.

Guessing a 350W ballast possibly will strike and run a 300W lamp but will allow it at a higher current, which may increase pressure in an already high pressure lamp, failure may be non passive.

**Bryson** · June 20, 2023

2 hours ago, musht said:

failure may be non passive.

This is a delightful piece of understatement. 😉

KevinE · June 20, 2023

A modern solid state ballast is going to run the lamp at the ballast rated output, whether the lamp likes it or not. Under running a larger lamp may work, it may flicker or not strike properly, overheat, cycle or simply be dim. Likewise a ballast that's too large for the lamp risks over running it. The lamp is in no position to demand exactly what it needs, the ballast gives it and the lamp has to comply...or explode. Best put the right lamp in for the fixture and leave it at that.

partyanimallighting · June 20, 2023

Thanks musht, regardless of what lamp is used, the ballast will only run at it's rated output. So obviously dropping a 350 watt ballast on a 200 watt lamp would be catastrophic for the lamp. Has anyone in this forum ever witnessed such an event or been crazy enough to try it just for s^its and giggles? I've enjoyed having a 330 watt ballast explode while I was checking a serviced fixture and it was spectacular. It also took me quite a while to get the cat down off of the ceiling. So, as KevinE rightly stated, the right ballast for the right lamp. Here's another question based around this premise. Would replacing or rather downsizing say.....a Philips 350 watt lamp and it's 350 watt ballast to a 330 watt lamp and a 330 watt ballast in a unit have any type of detrimental effect? I would think the major issue would be lamp cooling but these two lamps and ballasts are quite similar and I would think that it should function, being fed similarly via a 380W 1 Amp power supply. One issue would be the lamp size as the 330 watt lamp is 56MM and the 350 watt is 58MM. I would "assume" the unit would function adequately and I'm "assuming" the only issue would be a minimal loss of lumen output. Does this sound like it makes some sense? Or will "failure be non-passive"?? 😂

pmiller056 · June 20, 2023

Read the manufacturer's datasheets for the lamps and the ballasts you are trying to mix'n'match before trying anything. Depending on the manufacturer, there should be compatibilty information included in this documentation. Use the lamps that the ballast was intended to run. Different lamp technologies will have different ballast requirements, even for the same output power. Without further research, your proposal is likely to end with expensive equipment being wrecked for no good reason.

sunray · June 20, 2023

My only experience of such devices had been with overhead projectors, I believe the original bulb was about 50-60W and at failure a 100W used (being the size used in the newer OHP's). I was part of the 'audience' when the smoke started wafting across the projected image and within very few seconds a total obliteration of said image coincident with a big bzzzzBBmm sound with dark and silence.

It became my 'project' to clean it out... not a lovely job! and fitting a replacement ballast supplied by the lab technician, The new ballast was significantly physically larger than the original but a drill soon provided the fixing holes in the right places.

The replacement bulb still looked OK so refitted and struck. These thing took maybe 30 seconds or even more to fully illuminate, the latest combination went through the range of tints from a dull orange through green and blue to wite and bang as lumps of molten glass embedded themself into the underside of to the plastic fresnel lens. Assuming the bulb had been damaged when the original ballast overheated, a replacement was fitted and the explosion repeated.

Those several lunchtimes at school soon taught me it is essential to use matched/compatible combinations of bulb and ballast.

However moving on 25 years years to my nightclub work I was in Martin Professional in Maidstone and their 'test bed' for discharge lamps consisted of a rough sawn wood plank and bulbholders for all sizes from HTI (150W?) to MSR (1200W) (please excuse if those are wrong, remembering from mid 90's) and just the one very large ballast.

musht · June 21, 2023

issue would be the lamp size as the 330 watt lamp is 56MM and the 350 watt is 58MM.

2mm is double the length of the arc in a 5r lamp, it ain't going to be bright or narrow.

Beam lights really need the tiny source right in the focal point.

csg · June 21, 2023

another consideration is the focal length of the lamps reflector - they my very well be the same between two models of lamp, but without the relevant data sheets...any changes here would obviously have effects on the optical train

partyanimallighting · June 22, 2023

Thanks all. pmiller056, I can easily download the datasheets for the respective lamps but a quick search for ballast datasheets drew a blank......well, not a blank exactly, but data on those big clunky metal halide ballasts, not the smaller ballasts used in movers and these ballasts in movers have practically no information on their labels. Are there any links for ballast data that you know of?

sunray, isn't it strange that a 50 ~ 60 watt lamp would cause a 100 watt ballast to fail? I would think it would be the other way around. But, as was stated, the correct ballast for the correct lamp. Very amusing to hear that Martin tested lamps on a plank of wood back in the day though 🤣

musht, I was referring to the actual physical diameter of the reflector. The Osram Sirius 330 is 56MM and the Philips 17R is 58MM. These two lamps appear to be identical but......

I'm just seeking further knowledge on the workings of the HID lamp so all this information and any more information is very much appreciated.

partyanimallighting · June 22, 2023

Well, here's a good example as to the reasons for these questions/queries. I was looking for a replacement ballast for a moving head a while ago. Simple enough. The lamp is a 350W Philips Silver and I've attached pictures of the ballast label and the mosfets from the mover. A supplier from whom I purchased before recommended that I use their ballast but the label on their ballast states 330 watts. Now I have the blown 350W ballast and an old 330W ballast from the same supplier and, to give some sanity to my questions/queries, I checked the mosfets on both ballasts and they both use the same mosfets etc, 20N60C3, STTH15R06FP and FDPF51N25, yet one ballast is labelled 330 and the other 350. To my aged eyesight, these two ballasts appear identical and I even removed to mosfet heatsinks to get clearer pictures to confirm. Once again, back to the original question, will the 330 work instead of the 350 as "recommended" by the ballast supplier? I AM planning to purchase the "original" ballast for the 350W mover directly from the manufacturer but this question still lingers. Will that 20 watt difference in ballast output be the difference between a fully functional unit and a panicked search for a fire extinguisher?