Metal Halides - any experts?

[Tiny Spark]

So this is a somewhat open ended question and ime not entirely sure what it means but ime hoping someone will lol.

So as with most factories with have a load of metal halides of differing wattages and makes but mostly 250w.

Now today my boss showed me a incident report from another facility where one fitting had caught fire.
The culprit apparently being the "starter coil" which I am assuming is what I would call the ballast?

Now the reasoning behind the starter coil catching fire was apparently it was not a timed unit i.e. Once the unit had failed to strike (in this instance because the lamp had been removed) the unit continued to strike until it set on fire.

Now ive seen plenty of metal halides burn out in various ways but this is a new concept to me so...

Heres the q, do the ballasts have built in timers and if so how do you tell if it has?

Cheers guys.

 

[Barry White]

not an expert but there are 2 types of ballast theres the inductive type (just like a florescent light and this controls the currant ) and theres electronic ballasts which produce a high frequency to drive the lamp.

the inductive type is large and heavy the electronic is much smaller and lighter.

The bulbs had an bitmetalic contact in the bulb to stop it restriking whilst warm there is suposidly a newer electronic ballast that will light a warm bulb (rep tried to sell us them) but not seen them (maybe it has a timer in it?) I would contact the lamp manufacturer who usually are very pleased to supply info

seen loads of fittings without bulbs without any problems

 

[bigdavs83]

By starter coil I would assume it would be the igniter which sits along side your ballast and your capacitor. I haven't seen any go on fire though. Normally it would go out on fault and trip I have seen fluorescent gear (switch start) start to smoulder which has set off smokies.

 

[Flanders]

I was under the impression that if you do not replace warn out lamps or do not have a lamp in the fitting then the ballast will burn out , Normally they then short out and blow the trip/fuse but can course a small fire inside the light and as said set off a local smoke detector , the problem is these days no one as routine maintenance done to replace lamps they just wait until it gets too dark normally in the winter than call you out and you find you are replacing fittings not just lamps.

 

[Brightspark2]

It's the ignitor not the ballast that they are talking about...

You get ignitors with and without timed cut out. Look at the ignitor and it will tell you if it has a timed cut out on it...

As said though I'd usually the ballast that kicks out all the smoke and burns when it goes. You can smell it a mile off, it operates the protective device by the point though...

 

[Flanders]

It's the ignitor not the ballast that they are talking about...

You get ignitors with and without timed cut out. Look at the ignitor and it will tell you if it has a timed cut out on it...




As said though I'd usually the ballast that kicks out all the smoke and burns when it goes. You can smell it a mile off, it operates the protective device by the point though...

Yes that normally the way to trace the fault just follow your nose

 

[nickblake]

With the old metal halides as with fluorescents if the lamp has gone the ignitor is constantly trying to start the lamp , the ballast then draws excessive current (you can here this when the ballasts first strike they buzz quite loudly untill up to the running voltage when the current drops) this then causes the ballast to over heat, the insulation breaks down, the resistance of the coil then drops ,causing the ballast to catch fire or basically smoke and melt till it blows a fuse most low bays have fuses in them which normally blow before the ballast breaks down ,some ballast will fail due to the heat and age,but normally i have found is caused by lamp failure, after years of working with metal halide this is the conclusion i have come up with

 

[rapparee]

If the starter goes, i put in a master phillips bulb it has an internal ignitor in the bulb saves rooting about with fitting

 

[Tiny Spark]

Cheers guys, maybe its just the way they worded it then as i had never heard of a timed ballast.
The parts they listed were "starter, starting coil, capacitor"

Which I took as ignitor, ballast and cap.

Ile have a look on a spare ignitor tomorrow, never really spotted a timer function but then i have never really looked lol