# Difference between HPL 750/115 and 120's



## apaddle (May 31, 2006)

What is the difference between hpl 750/115 and 120's, I will be using them in ETC Source 4's if it matters? Thanks.


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## farmerjo1111 (May 31, 2006)

The 115/120 refers to the voltage of the lamp. If you have 115v at the outlet where you plug in the fixture you should use a 115v lamp. However if your outlet is outputing 120v you should use the 120v version. You can use the 120v version even though your outlet maybe only outputing 115v the light just won't appear to be as bright as it could be. If you put it the other way with a 115v lamp into a 120v outlet the lamp will be brighter than normal but you will have a shorter lamp life. Most theatres just use the 115v version as most places have 115v or close to it at the outlets. Did that answer your question?

Dustin Strobush
ETC Systems Group


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## apaddle (May 31, 2006)

Yes, we have 750/115's and 120's and I was just wondering which to go with. Thanks


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## koncept (May 31, 2006)

also on some dimmer racks you can specify the output voltage for dimmers. i know our sld rack we could tell one dimmer to run at 115 and another at 120


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## ship (Jun 1, 2006)

Normally/generally the 115v version is used in other than architectural non-dim installs or where lamp replacement costs are not a large factor. (For those of the 240v world, this would be the same in the 230v verses 240v lamps concept I would think.)

Measure (or have someone qualified to do so measure) the voltage at the fixture before adjusting the dimmer. Voltage drop or line voltage at the fixture is normally at 118v by the time it if starting at 120v gets thru the dimmer and all the way out to the circuit. That's given what you have feeding your building is 120v. If say 125v, this would tend to blow up lots of 115v lamps. On the other hand if you are starting with a 110v feed to the building as also possible, than the amber shift of a 120v lamp would be very wasted in your use. Voltage to the building as with actual voltage to the circuit can vary. Make sure who ever is checking voltage at the fixture is checking it under load and not alone because the meter probably won't have enough resistance alone to accurately meter the voltage.

115v lamps were designed to both operate slightly over their rated voltage so as to gain a higher color temperature and output - making them seem as if say a 1,000w lamp, and in compensating for line losses in voltage that for other 120v lamps normally does not allow it to get up to it's full output.

Next option after voltage class would be the high output or long life lamps. You should have four choices in this lamp wattage. Again, high output/short life (300 hours when operating at it's rated voltage be that voltage fed to the light 115v or 120v) or long life (1,500 to 2,000 hours) when operated at it's rated voltage. High output is as it says it is, a higher output lamp at the expense of lamp life.

Couple this with the other way of manipulating lamp life verses output - by way of voltage and you get four choices for a lamp. Say small, medium, extra large and super sized for this lamp by way of lamp life.

750w/115v high output lamps are normally used in the professional industry where budgets are high and lamp costs don't really factor in verses intended use. Such lamps provide the crisp blue color temperature and high output. Lamp life should be in around the 200 hour per lamp range in actual non-dimmed usage. Given use of a dimmer, it all depends upon the show for actual usage and dimming of the lamp but as a rough figure perhaps the need to replace one lamp per 1.1/2 seasons.

750w/120v high output lamps are less normally used. Their main usage would be in cases where one needs a high output lamp but are not using a dimmer or are subject to voltage spikes and other problems in the system. The lamp should be still fairly blue but not as hot as that of the 115v version. It should also under normal usage extend the lamp life around 100 or so more hours. (actual formula below note especially the GE note on operation of lamps at greater than 110% of their design voltage - this is very important.) If you need a high output lamp but don't really have budget to replace 100% of the inventory every say as rough figure, every year and a half, perhaps the 120v version would be a better option as next best.

750w/115v extended life lamps. This would be a better lamp for most theaters that don't have a large budget. Such lamps would last almost as long as say a Fresnel - almost to the extent that you probably won't notice the difference in lamp life operationg costs. It's going to be a more amber light than the above but should still be hotter than or at least similar to that of normal 750w halogen fixtures. The lamp life is more in the range of say 1,200 hours in giving up output while at an expected 118v for more lamp life.

750w/120v extended life lamps. I buy them for customers that are strictly install or having problems with voltage spikes. It's in output similar to that of a high output 575w lamp but much more dim or amber than even that of a say EHG lamp. If installing your fixtures outside in the winter, this lamp will likely be a good lamp. Otherwise for the wattage, while the lamp life would probably be in the 1,800 to 2,200 hour range, the light output is not so good and more in the 500w range.

v = Volts - A measurement of the electromotive force in an electrical circuit or device expressed in volts. Voltage can be thought of as being analogous to the pressure in a waterline. The effect of voltage on a lamp will cause a significant change in lamp performance. For any particular lamp, light output varies by a factor of 3.6 times and life varies inversely by a factor of 12 times any percentage variation in supply. For every 1% change in supply voltage light output will rise by 3.6% and lamp life will be reduced by 12%. This applies to both DC and AC current. Most standard line voltage lamps are offered at 130v. Since most line voltage power is applied at 120volts, the result is a slight under voltaging of the filament. The effect of this is substantially enhanced lifehours, protection from voltage spikes and energy cost savings.
Voltage and Light Output: The effect of voltage on the light output of a lamp is ±1% voltage over the rated amount stamped on the lamp, gives 3.1/2% more light or Lumens output but decreases the life by 13% and vise a versa.
Do not operate quartz Projection lamps at over 110% of their design voltage as rupture might occur. GE Projection, Ibid p.13
A 5% change in the voltage applied to the lamp results in
-Halving or doubling the lamp life
-a 15% change in luminous flux
-an 8% change in power
-a 3% change in current
-a 2% change in color temperature (0.4% change per1% voltage.)
Osram Technology and Application Tungsten halogen Low Voltage Lamps Photo Optics, p.21


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## PhantomD (Jun 3, 2006)

koncept said:


> also on some dimmer racks you can specify the output voltage for dimmers. i know our sld rack we could tell one dimmer to run at 115 and another at 120



Our 240V dimmers have variable curves, one of which is a 120V curve, which means we can run both 240V and 120V luminaires.

Slightly offtopic, but meh.


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## Chris15 (Jun 3, 2006)

PhantomD said:


> Our 240V dimmers have variable curves, one of which is a 120V curve, which means we can run both 240V and 120V luminaires.
> 
> Slightly offtopic, but meh.



The normal practice is to run a pair of 120v lamps in series for 240v. If you do use a 120 volt curve, make double sure that you don't plug a 120 v lamp into a 240 v channel. Otherwise, I suspect that you will discover the quickest way to destroy all your globes.


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## PhantomD (Jun 6, 2006)

We have no 120V fixtures so it's no problemo. 

I was aware of that!


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## Chris15 (Jun 6, 2006)

I was not meaning to imply that you did not. It is only really a problem if you are doing a show that uses the same connectors for both 120 and 240, then you can start getting into trouble. I guess that Jands build the 120 curve in so that you can do say a PAR64 on its own should you so desire. The problem with running in series is that if one globe goes, they both go, so for that reason, a 120 curve and the lights in series would be more effective, it would just trip the breaker.


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## ship (Jun 8, 2006)

So I'm wondering why those of you in the 230v world are not using HPL lamps in the 230 to 240v range instead of wiring them in series? Is the output or refinement of the filament of a 115v lamp that much better so as to provide rational for this, or is it just that it's easier to duplex all fixtures in an inventory? This such as while also available 230v PAR lamps not used in favor of 120v PAR lamps?


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## Chris15 (Jun 9, 2006)

ship said:


> So I'm wondering why those of you in the 230v world are not using HPL lamps in the 230 to 240v range instead of wiring them in series? Is the output or refinement of the filament of a 115v lamp that much better so as to provide rational for this, or is it just that it's easier to duplex all fixtures in an inventory? This such as while also available 230v PAR lamps not used in favor of 120v PAR lamps?



As for HPL lamps, I don't have the experience to comment, but with PAR lamps, the done thing is to use 240v PAR56s and 120v PAR64s. When you run 12 pair of PAR64s, you can normally get away with running them off a 32 amp 3 phase outlet (which is standard down here). So I don't know why it is that way, it just is.


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## Chris15 (Jul 5, 2006)

Sorry to revive an old thread, but I thought it worthy to note something that I have just read in relation to the 120 / 240 question on PAR lamps. The answer, it seems is in lamp life. The article I'm reading says that 120v lamps were used for their 2000 hr life as opposed to the 300 hr life of the 240v equivalents. So it seems that they don't make long life versions of PAR64 in 240 volt. That may very well be wrong, but it would seem the most logical explanation.


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## cutlunch (Jul 5, 2006)

ship said:


> So I'm wondering why those of you in the 230v world are not using HPL lamps in the 230 to 240v range instead of wiring them in series? Is the output or refinement of the filament of a 115v lamp that much better so as to provide rational for this, or is it just that it's easier to duplex all fixtures in an inventory? This such as while also available 230v PAR lamps not used in favor of 120v PAR lamps?



I can agree with Chris's last post on why they are using 120V lamps in their Par 64's but it doesn't seem that common here in New Zealand. I may be mistaken though. One reason I don't think it is so common is the need to have special leads made that take two Par 64's and run the two in series. This just adds to the hassle when rigging compared to the 240V Par 64's that can be plugged in anywhere. I'll try and do more research on this topic.


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## ship (Jul 5, 2006)

I had not noticed the 300 hour listing on the Euro lamps. That would make a large difference given the choice of either 800hr or 4,000 hour for a 1Kw /120v lamp.

I do note voltage ratings of 220, 230 and 240. The 240v lamp while it would loose some in intensity should eek out a bit more life but not enough I suppose.

Do you find while using the lamps in pairs that if one blows the second quickly follows in changing both at the same time or is the filament rugged enough to withstand a moment of the other lamp arcing and the second lamp getting full voltage for that moment? I know on DHA light curtains granted using a very low voltage lamp, once one lamp blows, the rest get changed. But with other series lamps such as the 4596 in a ACL/Audience blinder, or even EYC lamps in a Mini-Cyc, only that lamp that went bad is changed. In both cases however one lamp blowing still has a fair amount of resistance between a few lamps as opposed to directly on only one such as in the case of a PAR 64 in series. 

Wonder also if this momentary arc when the other lamp blows would seriously effect the lamp life of a second HPL lamp in series with it. This doubling of voltage even if only for a micro second would seriously cut down on the expected lamp life I would think.


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