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Author Topic: ACL & 28v lamps  (Read 2713 times)

Giacomo Iiriti

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ACL & 28v lamps
« on: November 07, 2007, 07:13:31 am »

I'm relatively new to acl and 28 volt lamps. Recently I bought a set of 8 par 36 with two bars and 28v 250w lamps (the same par36 lamps of audience blinders). This is a small acl set.
The first time I've used them, a lamp blowed down. I've changed it and used them again for about 1 hour (4-5 times for 30 seconds max). Then other 3 lamps blowd down. Lamps are by General electric.
So, a lamp costs about 15 euros... what an expensive strange object i've bought? How can I solve this problem? Maybe preheating lamps? Why lamps blow down so quickly? thank you
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Tony "T" Tissot

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Re: ACL & 28v lamps
« Reply #1 on: November 07, 2007, 05:04:46 pm »

The first question:

Are they all (eight) wired in series across 220V?
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Giacomo Iiriti

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Re: ACL & 28v lamps
« Reply #2 on: November 08, 2007, 06:20:28 am »

yes, they're correctly wired.
if is important, the blowed lamps are completely white in front.
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Jim Brooks

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Re: ACL & 28v lamps
« Reply #3 on: November 09, 2007, 09:01:28 am »

I use the 28 Volt, 250 watt, par 64 lights (GE-4552),
and 28 volt, 100 watt, par 36 lights (GE-4594).

Must have an inline fast blow fuse (breaker is too slow).
Old lighting guy clued me in.

4 lights times 250 watts is 1000 watts total, 10 amp fast blow fuse.
When a bulb blows the current rises just enough, just long enough, to either weaken the filiments or blow the other three lights.
The fuse will blow quick enough so that won't happen.

The bulb has a 25 hour life.
Not really designed for constant flooding of the stage.
I use mine for back lighting.
I use par 64 1000 watts bulbs for the front flood.
They have a 2000 hour life.


Jim Brooks
casperband.com
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Giacomo Iiriti

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Re: ACL & 28v lamps
« Reply #4 on: November 09, 2007, 11:38:35 am »

thank you. So, my lamps are 250w 28v. I'm under 230v (italy).
So, 2000w at 230v. 9 ampere at full power. right?
so i have to build a little box with a rapid fuse and insert it on the line output of the dimmer channel who's serving the ACL? a 10 ampere fuse is right? Thank you!
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Brian Ship

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Re: ACL & 28v lamps
« Reply #5 on: November 10, 2007, 01:42:59 am »

Preheating the lamps would be advisable on a dimmer as with replacing all as you replace one so they have the same lamp life and expiration.  That’s so if wired in series, one lamp blowing doesn’t mean in all future gigs you constantly face that problem.  Can never heart pre-heating the lamps.

I like the resister idea, don’t use it myself but it’s a good one.

I think you still have a problem here.  8 lamps x 28v = 224v.  This given you are at 230v if not 240v at times is problematic if at full intensity for such a high output/short life lamp.  In the US we are also using such lamps at over their operating voltage but perhaps not as much dependant upon drawing their given lamp life out of them given an over operating voltage condition.  This also a little less dependant upon basing any one lamp of value once one in the series blows for reasons explained.

Test how many shows such lamps can last dependably when operating in an over rated voltage condition for these low voltage lamps, subtract one show and replace all of them would be a recommended solution.  That or sell them off and get other fixtures.  These are for use for bursts of light and might not be within your needs for them as a concept.
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Giacomo Iiriti

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Re: ACL & 28v lamps
« Reply #6 on: November 10, 2007, 05:13:47 am »

In italy I'm under 230v. Maybe i can use them not at full power.
However their use is only scenographic, only as acl! only little flashes for 3-4 seconds a time.
as soon as possible i'll try the rapid fuse solution, it looks interesting! thank you!
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