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High bay light ballas and ignitor

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New Member
Hi to all members,

i am new in this forum, i am using high bay 400W light in my work place, the ballast(choke) and ignitor of the light found very easily burnt out. can someone explain to me how actually ballast and ignitor works.


ballast (choke)
Brand: nikkon
240V, 4.4A, 400W HPS

brand: nikkon
model: SP9003
Watt: 70 to 400
lamp: HPI/HPs
I: 4.6A

Buld: sodium bulb


New Member
Hi, thanks for the info, now i know how the stuff works, but, i still cannot understand why my light burnt so frequently, specially i observe it happen when i switch it ON.


Does your supply have some problems?I mean does your main fluctuate?Also the light gets 'burned' i-e doesnt light up when the whole unit (ballast+choke) is faulty.In that case all new lamps will get faulty(burned in your case).So replace the unit.


Most Helpful Member
The standard HID (High Intensty Discharge) type lamps use whats called a constant wattage ballast.

That is, they try to put out the same wattage to the bulb reguardless of what the input line voltage does.
If the line voltage goes up they automaticaly reduce the incoming amp draw.

However they also will increase the incoming amp draw in order to make up for a lower than standard voltage. Because of this high amp draw state they have a minimum input voltage requirement.
If the line voltage drops below this minimum voltage level the bulb will still get its near full wattage it needs but the ballast will overheat and burn up the windings.

This may very well be what you are having problems with. If you can find the specs for your ballast, find out what its minimum running voltage is. IF your local power is dropping below this voltage for more than a minute or two it will burn them out.

You may have to add a boost transformer to make up for the difference. Just dont over boost on the normal line voltage and go over the ballasts maximum input voltage rating.


Yes, it's an HID lamp - totally different to a fluorescent lamp.

The ballast is normally just an inductor, an igniter is also sometimes required, I wouldn't know what one of these looks like or how it works.

Some modern lamps use a switched mode power supply but inductors are generally more robust.


New Member
Many HPS ballasts are CWA (Constant Wattage Autotransformer) or CWI (Constant Wattage Isolated). These ballasts have a capacitor in series with the lamp to regulate his current. The CWI's primary and secondary coils are electrically isolated, but aren't isolated in the CWA. Your ballast can also be an HX (High reactance autotransformer), essentially a CWA with no capacitor.

The ignitor creates a short-circuit for a micro-second between two specific places on the coils. That short-circuit will produce a inductive kick that will provide the open circuit voltage of around 3 to 5 Kv necessary to strike the HPS lamp.

Hope this helps :) If you have any questions, let me know!
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