Strange problem with 1000 watt metal halide bulb.

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Old 04-15-10, 12:28 PM
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Strange problem with 1000 watt metal halide bulb.

Hi everybody, I was wondering if any of you had any ideas on whats going on with my setup.

For a uni project I needed to have a really bright light source, so did a little research, decided to get a metal halide bulb. bought all the parts (ballast, capacitor, mogul base, 1000w bulb, correct wires)

wired it all up, plugged it into an extension cable, and took it into the middle of the garden (in case something happened) turned it on, and voila it worked fine. So over the next few days I did some experimenting with the light (long exposures in dark areas, shadow stuff, projection. etc)

BUT i always used the same extension cable when i was doing this (extension cable is 50m long, rated at 13amps, over 3000 watts when fully unwound)

Today I tried plugging it into the mains w/o the extension cable, it lit up, then died all within the space of 5 seconds - i checked and sure enough the fuse had blown. (it was a 13 amp fuse, and the ballast is only supposed to draw 8.5)

anyway, after much experimenting and many blown fuses later, ive found out the only way to get the light to work is to first plug it into the extension cable?! any other combination and the fuses blows.

So, im stuck tbh. the only thing i can think of is that the extension cable is acting as some sort of current time delay? and perhaps the ballast is drawing more than 13 amps on initial startup of the bulb.

here is a pic of the setup i have cobbled together.



Circuit diagram:

(I have it wired up for 240v, not 230v)
also im not sure if capacitors have negative and positive or not, it wasn't marked on the one i got.

Ballast info: (rest on the circuit diagram)

Capacitor Uf. 100
Height 98 mm
Ignitor SI52
Lamp 1000w
Length 220 mm
Width 116 mm

capacitor Info:
1000 Watt Metal Halide Capactior
24 uF (Microfarads)
480 VACr (Volt Rating)
Case Depth: 1.75" Oval
For Use with Ballast Voltage: 120/208/240/277/480
Qty: 1

Lamp info:
MVR1000/U/BT37 1000W METAL HALIDE LIGHT BULB

Base info:
New Leviton 8746 HID Mogul Lamp Base 1500W, 600V

Extension cable is 50m long, and (fully unwound) is rated at 13amps and 3000 watts

I think thats all the info i can give.



any help would be very much appreciated.
 

Last edited by davidsadler; 04-15-10 at 02:59 PM.
  #2  
Old 04-15-10, 12:55 PM
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Welcom to the Forums...

Though this is primarily a US/N. American site...we have some folks familiar with other AC systems. Not that that should really matter in this case...

Well, the experts may have an informed opinion...but I would say the extension cord (thats a long extension cord btw) is probably causing a voltage drop.

As to why the fuse blows...I'm not sure...you would think it would blow with the cord...

Lower voltage normally means higher amperage.

I would also have to say that the Pro's will need a wiring diagram and specs on the setup to be able to explain the problem.
 
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Old 04-15-10, 02:44 PM
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Thanks very much for replying, I will supply circuit diagrams and relevant info asap.

when you say the extension cord is causing a voltage drop, do you mean that this is whats enabling the bulb to work properly?

And im sorry about posting on an American site, i couldn't really find a similar English equivalent.
 
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Old 04-15-10, 03:01 PM
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Oh...no problem with the posting...and in this case it shouldn't make much difference. We aren't dealing with codes or inspections.

And yes..thats what I meant about voltage drop. Why it would make a difference..I'm not sure...but thats basically the only thing that adding the length of ext cord will do. Granted...I think you use 230-240V over there(?) so the voltage drop might be less...but thats all I can imagine that would affect the circuit.

If you feel like it...check the voltage at the input to the circuit you built, with and w/o the extension. WIll prob cost you another fuse of course...
 
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Old 04-15-10, 03:08 PM
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Ok, but when you say check the voltage, is that...with a voltmeter? sorry im not exactly sure.
 
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Old 04-15-10, 03:21 PM
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Actually i have a video of the bulb trying to start. i could upload it if would help?
 
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Old 04-15-10, 03:35 PM
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Yes, check with a voltage meter across the energized circuit. But what would really help is using a clamp-on amp meter to find out the amperage. Also it might be best to use a time delay fuse. There may be an inrush of current as you suspected blowing the fuse during warm up. Do you know the total amp draw when operating? it will exceed the 4.6 amps (1000 Watts) of the bulb because of the ballast. You are pluging into the same circuit? What other loads are on the circuit?

Hang in there Marc one of our our lighting experts who is familiar with UK electrics is on Paris time. He will probably be along later.
 
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Old 04-15-10, 03:44 PM
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im afraid i cant tell you the volts or amps, because i dont posses a voltmeter or ammeter, although i can pick them up this weeked.

as for the time delay fuses, thats a very good idea. i appreciate that you live in the US, but do you know if I can get time delay fuses that fit into UK plugs?

and nope, its a closed circuit - nothing else wired into it. just the bulb, capacitor and ballast.

thanks for replying.
 
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Old 04-15-10, 03:53 PM
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Since we don't have ring circuits so we don't use fused plugs so info about the fuses in plugs I can't answer. Here in the US though it is common to use time delay fuses in fuse boxes supplying inductive loads such as motors. Most cases though we use breakers now and all commonly used residential breakers are time delay.
 
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Old 04-15-10, 04:01 PM
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Old 04-15-10, 05:40 PM
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Yes, if it fits it should but really doesn't explain the extension cord anomally.
 
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Old 04-15-10, 05:43 PM
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yes it is very odd, i asked around and everyone says they cant think of a reason why.
ill take some readings when i get the equipment, and try the new fuses when the arrive, and see if its any better. if not, i guess ill just have to carry round the extension cable every time i want to use it....

thanks alot for helping out.
 
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Old 04-15-10, 07:54 PM
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Ok I can see the situation however did you actally hook into 230 volt tap instead of 240 volt tap due some case it will be too high a voltage and it can draw a bit more current.

And with CWA ballast they will draw more current during start up but once it warm up it will drop a bit.

For your ballast with High power factor it should be in mid 4 amp range but if you have low power factor ballast then it will be much higher on current drawage.

I just can't really read the ballast model number very clear so can you take a other photo for moi ?

For the time delay fuse in your plug socket yes that is correct one.

Merci,Marc
 
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Old 04-15-10, 10:00 PM
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Originally Posted by davidsadler View Post
yes it is very odd, i asked around and everyone says they cant think of a reason why.
ill take some readings when i get the equipment, and try the new fuses when the arrive, and see if its any better. if not, i guess ill just have to carry round the extension cable every time i want to use it....

thanks alot for helping out.
an amp-meter has to be clipped on a singles wire...it cant be clipped around say an extension cord....just so you know
 
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Old 04-16-10, 06:12 AM
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Originally Posted by french277V View Post
Ok I can see the situation however did you actally hook into 230 volt tap instead of 240 volt tap due some case it will be too high a voltage and it can draw a bit more current.

And with CWA ballast they will draw more current during start up but once it warm up it will drop a bit.

For your ballast with High power factor it should be in mid 4 amp range but if you have low power factor ballast then it will be much higher on current drawage.

I just can't really read the ballast model number very clear so can you take a other photo for moi ?

For the time delay fuse in your plug socket yes that is correct one.

Merci,Marc
So you recon to try wiring it up for 230v will fix it?

i will take another photo asap

thanks for replying.
 
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Old 04-16-10, 06:35 AM
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ok wiring it up top 230v did not fix it, bulb ignited, lit up, pulsed a bit then just went... Bzzzt and died. and the fuse had blown.

here's a better picture.

 
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Old 04-17-10, 08:17 AM
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Just to let any body know whos still reading this, i tried the slow-blow fuses, nothing happened with the bulb. at all.

now it wont start at all, with any configuration. i also re-wired the whole thing, in case it was a faulty connection. it isnt blowing fuses, its just doing nothing...

I read somewhere that in these type of circuits the capacitor is usually the first thing to go, is it worth replacing it or shall i take it to the physics department of my uni and see if they can help?
 
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Old 04-18-10, 12:43 AM
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Sorry took me little longer to dig up this number and this is a reactor ballast aka choke coil ballast and this one is not my favour ballast that draw way too much current for the bulb size.

Did you hook the capaitor as you see on the right diagram ? if so you may have wrong capaitor on it.


Normally we like to use the CWA { constant wattage autotransformer } ballast that will draw far less current than reactor ballast is the CWA will draw about 4 amp just about almost half what you have on it now.

If you want CWA let me know I will get a hold of UK sparkys they will give me the location where to get the CWA ballast for your useage just give you a head up the CWA will cost more than reactor ballast I don't have the price list for UK side but in France yeah I can able run the price it will be about 100€ to 150€ or so

Some case we get new ballast that can go bad real fast as well from time to time we get one that toasted real quick.

I have other trick to deal with stubborn ballast but I will save it until last resort.

Merci,Marc
 
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Old 04-18-10, 03:34 AM
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Thanks alot for replying.

Im positive the capacitor is hooked up correctly, and is the correct one, its designed specifically for metal halide bulbs of a 1000w. do capacitors have a positive and negative?

1000 Watt Metal Halide Capacitor / 120-480 Volts: Light Bulbs Etc, Inc.

yes that would be very kind if you tell me the whereabouts to pick up a CWA ballast, i live in west sussex by the way. if they dont have a dealer near me, perhaps they have an online site i could by one from.

Just one more thing ive noticed that when i switch it on, the bulb makes a very quiet fizzing sound, i hadnt noticed it before. just wondering if that was important or not. the ballast is silent.

shall i try and return the old ballast?

thanks again for helping,

dave.
 
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Old 04-18-10, 02:23 PM
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although, is there any way to get this ballast i have at the moment to work? its got to work somehow right?!

do you have any idea why the circuit isnt working at all now

would this ballast be suitable?:

https://www.lightbulbsuk.co.uk/ventu...sodium-ballast
 

Last edited by davidsadler; 04-18-10 at 02:42 PM.
 

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