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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => SR Forum Archives => Lighting FUD Forum Archive => Topic started by: Brian Ship on August 17, 2006, 10:21:54 PM
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Is the VL-1K with 115v halogen lamp format correcting for it’s normal nominal 120v operating conditions or is it a 115v fixture normally used at 120v nominal voltage operation?
Looking for advice on and other ideas and things to check on premie lamp failures beyond what I’m working on and need to see the failed lamps to further refine the cause of. Lamps going bad early is a bad thing. Also fact checking where possible. (My figures below are a laymen’s figures in doing the math and hoping that I remember math class sufficiently 20 years back on these equations - or at times re-trying the math until it became a sensible figure. Ethics courses seemed like a great alternative to actual math courses back in college.)
Got wind of a customer who noted that his VL-1K incandescent fixtures were not living up to their expected lamp life. So far, it’s a warranty replacement. Do VL-1K fixtures have lamp life counters especially given a dimmer that I could have a valid warranty claim to my own suppliers in doing? In fact, some of the lamps as described were only lasting a week -that’s a bad thing. I assume this is the dimmer 115v version.
I don’t use moving lights but buy the lamps for them and while where I work owned/used or still owns such fixtures, I don’t remember any complaints about short lamp life or runs of lots of them going out on this specific lamp that was more than usual, but than again it was not permanent install use. At no point while using them on say a tour did the lamps seem to go bad faster than other lamps a HPL lamp rated for the same lamp life and voltage in comparison also on similar tours. This given the HPL lamps most likely are on dimmers in extending the lamp life and perhaps these fixtures are normally at max intensity so as to have more punch than the conventionals. Still these lamps while I stocked a bunch of them did not die per say faster than a normal moving light would eat thru lamps at any point noticable.
Didn’t see much in the manual on this specific question. If it’s a finger fucking (caution technical term the webstie filters should have picked up but definate and valid professional technical term defined as a quartz glass lamp touched by the insaller's fingers) or say really bad bench focus - lamp touching the reflector problem in it by pressure against the reflector causing the pinch to fail, my time spent will become obvious quickly upon examining the on-route bad lamps.
Overall I recommended to the sales person in things to say to the customer to take a voltage reading at the fixture and if possible to measure the peak voltage during normal usage to see if there is any voltage spikes. In reading the manual a secondary question will be if it’s run off a stage dimmer system as opposed to hot non-dim power source, though I doubt it would have anything to do with lamp life should this have been the case. Bad Karma to double dimmer such fixtures. Also to clarify if it’s a dimmer version or non-dimmer version of the fixture which will help some in lamp life expectations - I don’t expect it’s other than dimmer version however.
Than in inspecting the fixtures, ensure that the fan is working - the manual was confusing about if it’s heat sink or fan dependant upon the install application but did mention a fan at least in some conditions of use so I expect that the lamp is fan cooled for the most part. Fan not working would provide a lamp overheating that most likely would be a pinch seal problem in the lamp’s failure as opposed to broken filament that could be shock, voltage or even expected lamp life base or cause and dependant upon what the filament itself looks like where it breaks in addition to say flat spots and or smaller zones of it. Possible that the fans are not working and need to be, could also be a case as similar to a old Colemar CF-7 pre-upgrade where the fans shut off at a bad time in the programming which tended to blow up a lot of lamps. Soft where upgrade given it’s not a heat sink sufficient cooling application?
Lamp base itself could also cause a pinch seal overheating problem and would be noticeable by way of inspecting the lamps’ pins. I don’t think these lamps are Blue Pinch, P-3, O-3 or what ever Phillips and Ushio call their proprietary but copied pinch seal advancements. Could be a factor in concept if the pinch failed due to overheating. Should there be discoloring of the bad lamp's pins, pitting, arching and welding of them, it's probably a bad lamp base that is a wear an tare issue of the fixture and would in any fixture explain lamps going bad sooner than normal. All about surface contact. Not good means lots of current flowing thru a very reduced area which means lots of heat and potentially less voltage to put asside as a factor for the moment. Could also be bad wiring to the lamp base as a factor however in causing heat inside the fixture but the electronics would probably fail first were this the case.
The bad lamps are on the way back for me to inspect.
It’s also at least as a theory possible that if it’s in a club and the dichroic coated reflector is dirty that the lamp could overheat to some extent. Viewing the bad lamp will rule out some things and open up possible causes for the premie lamp failures for the most part. Also if last time I sent the customer say Phillips, this time it will be Ushio though I doubt either is better. I’m yet to have a bad lot number of lamps from either brand for this specific lamp but it’s possible they have a bad lot. The bad lamps will be going back to where ever they are made for final determination on this unless obvious failure cause such as a bad fixture lamp base, fingerprints or elephantitus of the globe often due to touching it and similar end user caused problems. As long as I stay atop the manufacturer in questioning what caused a specific failure, there might be a chance I get word back as to the specific cause of failure. Unfortunately normally the vendors just send a credit when their fault. Sure send them a very complete history of the lamp in question - each specific lamp yet only get a credit at best or nothing in response.
What I might also have the customer look into is the trim setting of the internal dimmer on the fixture. Is it pre-heating if that’s a thing this fixture does, and given the fixture is rated for 115v, is it correcting for a 120v install or at 120v at the lamp base? Does it go from Zero voltage to FF or is it pre-heating the lamp before zeroing the fixture in plugging it in? Does it maintain a current to the lamp while not in use or is it cold starting every time?
If in a area that receives voltage spikes due to their or supply spikes, or has high voltage such as say 125v - I have seen this before in both conditions, can they install variable resistance dimmers to feed the fixtures which by way of transformer and not sinewave chopping limit the voltage to 115v? Otherwise install 1:1 voltage regulating transformers so as to control voltage spikes by way of lag time? This assuming a power source problem. Expensive option but in testing the fixtures and finding a serious problem, this might be the only solution in using 115v lamps. The 230v world has a VL-1K lamp that's rated for 250v available, the 120v world only has 110v and 115v choices to choose from. Can't see using a 110v lamp other than in serious voltage drop or 115 to 110v conditions of supply. Very rare from what I see to have a need for a 110v lamp.
Did some rough calculations also on this lamp as similar to that of the HPL lamp. If the above did not mean anything to S-4 and even HX-600 series (GLA) lamp using people, the below should for at least perminant install purposes.
For every 1% voltage change upward on a lamp, the Luminous Output goes up 3.5 to 3.6% more, Color Temperature goes up 0.4% more and Lamp Life goes down by 12 to 13% dependant upon what source for information you are reading. Also filament lamps are not recommended to be used at over 110% of it’s rated voltage or rupture might happen. That’s standard lamp data no matter if MR-16 or S-4 fixture all lamps live under. The higher the wattage, possible in theory the better able to cope with a voltage spike but also probably not sufficiently. The larger voltage lamps certainly can contend better with voltage spikes such as turning on a bunch of moving lights or strobe lights in that moment after they gain the arc.
I doubt it’s shock but given it’s a moving light possible. Should I see a filament that broke free from a heavily supported 8c-13D filament hanger, it might be the case of a lamp which did not have enough support to withstand shock or perhaps a fast movement by the fixture. Doubtful as it might be.
First the easy, if there is voltage spikes, a 126.5v voltage spike should rupture the filament. Otherwise if this building has 125v instead of 120v feeding it as is possible, that’s going to be really harsh on lamps, especially perhaps this high output lamp.
Next, if a 115v lamp is operated at 120v, that’s a 4.166% change in voltage. Unfortunately unlike the 250v version for the 230v world, there is no 120v lamps available for our 120v as a standard system. There is a 100v version I simply could not imagine using. Should this say club have 120v if not even 125v, it would be very bad for lamp life. This especially if such lamps were at 100% dimmer intensity about all the time. 120 hours is the expected lamp life of this 300hr lamp if operated at 120v.
Five days of usage is 120 hours so it’s possible if the fixtures were left on at 120v in doing 24/7 operation that the lamp would fail naturally within a week. On the other hand a power supply of 120v but dimming to 103.5v or say 86% would extend lamp life to 339 hours. Should this fixture not have a trim setting for the dimmers, not going beyond 95% of output would mean a expected 300hr lamp life also.
A further factor of the lamp is the Color Temperature as it relates to filament failure. A filament melts at 3,655̊K in color temperature. 1.6666% increase in color temperature due to 120v operation is a 3,253̊K lamp all the closer to it’s melting temperature. Small detail but given a voltage spike or a lamp bouncing or moving about this could become a factor over a few hundred hours. Should it be a 125v normal voltage, it’s now at 3,302.4̊K and very fragile within a moving light.
There is where I’m at on this problem. Any help?