How many hours does a lamp lose on every strike?

Many people forget that the Halogen cycle does not occur below about 80% intensity. (temperature dependent.) If the lamps run at too low a setting, tungsten begins to deposit on the inside of the envelope and the lamp starts a death spiral. So, running the lamps too cool causes the expected lamp life to plummet! As counter intuitive as it sounds, they need to be run hot and bright to get the best life!
Of course, in theater that is not always possible. If there are certain fixtures that spend the whole show dim, then a nice hot ramp-up cue that leaves them on for awhile after the show can extend life.
 
A thought occurs. What's the cost benefit on electricity consumed running lamps in a warm up cue vs. saved money in extending lamp life and less replacements over time?
 
A thought occurs. What's the cost benefit on electricity consumed running lamps in a warm up cue vs. saved money in extending lamp life and less replacements over time?
Well, figuring a 575 watt lamp run for 5 minutes will consume 48 watt-hours, times 14 cents per kw, that comes to $0.006 or a little over 1/2 a penny. So, if you did that for 100 shows, it would cost 60 cents. The lamps are about $15 so if you recouped 10% additional life, that would be $1.50 or approximately a 200% return on investment. ...yea, I do accounting as a living now ;)
 
Hi all,

Re: incandescent lamps/Halogen lamps-
...Rated life of most HMI & HTI lamps is based on an assumed switching cycle of 60 minutes on, 15 minutes off. Which means it is assumed that a lamp with an avg. rated Life of 750 hrs. will be struck 12.5x over it's rated life. If it is struck more often than that, then the avg. rated life is expected to go down. If you strike it less often than that, then you should get more life out of it (again, assuming adequate cooling, ignitor/voltage conditions, etc.)....

I hope this help.

Cheers,
Mark

Mark, did you mean 125 strikes? if it was only 12.5 strikes, each strike would last for 60 hours, not 60 min.
Based on 125 strikes, I would think that this is more than most fixtures will reach before they exceed the rated lamp life.

now... tell us about the Pheobus Cartel....
:)
-Ford
 
What? 750/60 = 12.5! As Ford notes, math isn't my strong suit. *laugh* Yeah... missed that whole "hours/minutes" thing. Edit has been noted above! Thanks for catching that Ford! *laugh*
 
Above all a warmed filament rule I have always lived with - perhaps if not needed most of the show, it could become warmed a few minutes before need if a special as a concept. But mostly from what I have known, you always warm a lamp some so when going to full, or especially if strobing, the filament isn't shocked and or will go to full output sooner.

Here is a SOP where I work I installed. 2Kw Fresnel lamps are never to be directly plugged into an outlet. Each one tested in prepping for a show will be plugged into a 2Kw dimmer, and run up directly with care. Anyone guess why such a rule was needed? What does that have to do with higher than say a household 60w lamp in plugging in other higher wattage lamps?

Ah' Mark... that getting up to 3,000+ hours for a 750 hour lamp rating lamp is semi-old school practice now. I now have semi-approval of at 1,000 hours for a 750 hour lamp... it's ok to replace it. Granted that those that know this replace the 2-3,000 hour lamps at this point also in calling them old. Mostly I see these days most lamps are fairly frosted or vapor clouded over at least at this point at under 400 hours. So no it's not a total snowball in as if projecting a gobo with a fluorescent lamp, but mostly by 350hours modern lamps rated for 750 hours are fairly useless already. If a reflector lamp rated for 2,000 hours, too soon to tell at random at this point, but mostly they have clouds in them at 500 hours.

We are talking about completely different fixtures, and I would gladly go back to the final upgrades of the Mac 2K fixture over any VL-3K (in them getting more serviceable), or other elder fixtures such as a wash where if it's a snowball, it was still fine to the crew using it.

Most modern fixtures these days would be lucky to get to 750 hours before the efficient light output is "dim" well before expected lamp life. This includes the lamps rated for 2,000 hours.
 
...Realize that even though your board is indicating levels in 1% increments it's actually outputting with far greater precision with several steps within each percent. ...

I believe DMX has 256 steps over that 100% range - maybe this is just semantic, but I think 2.5:1 doesn't quite make it to a 'far greater' ratio. But yes, it's better than 100 steps to full, which I think was your point.

As for your pre- and post-warm levels, I'm not sure how much lamp life you're using at such a low level - it's bound to be something, though, although it may be negligible, or maybe even beneficial depending on your setup. Regardless, if it makes your show look the way you want it to look, then the lamp is doing its job for however long it lasts.
 
I believe DMX has 256 steps over that 100% range - maybe this is just semantic, but I think 2.5:1 doesn't quite make it to a 'far greater' ratio. But yes, it's better than 100 steps to full, which I think was your point.

As for your pre- and post-warm levels, I'm not sure how much lamp life you're using at such a low level - it's bound to be something, though, although it may be negligible, or maybe even beneficial depending on your setup. Regardless, if it makes your show look the way you want it to look, then the lamp is doing its job for however long it lasts.
And, perhaps more importantly to me, how much lamp life I'm saving along with achieving a smoothness of fades I'm looking for.
Thank goodness we're ALL still entitled to our own wrong opinions. ;^)
Toodleoo!
Ron Hebbard.
 

Users who are viewing this thread

Back