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shkim2000 (Electrical) (OP)
13 May 05 6:31
I have found it out that sodium flood light is turned off at short time on the vessel during large motor starting phase. In order to analyze the reason, Does anybody have internal circuit diagram of ballast for sodium flood light ?
SolderingGunslinger (Electrical)
13 May 05 13:24
The actual circuit can vairy from manufacturer to manufacturer, however the usual low pressuresodium ballast is an autotransformer with a capacitor in series wit hthe output.  The actual valuse and number of turns depends upon service voltage and the required voltage for the lamp.

You didn't mention if you have a high pressure or low pressure sodium lamp, however the previous description of a ballast would remain the same.

Chances are, when the motor starts, you have a slight voltage sag, either that or the lamp is on one phase of a three phase service and there is considerable unbalance on the service.

Put a chart recorder on the circuit which carrys the lamps load and cycle the motor.

I remain,
The Old Soldering Gunslinger
shkim2000 (Electrical) (OP)
17 May 05 9:15
It is high pressure sodium flood light. You mean that short time blackout is caused from voltage drop. Is there any other all possible reason ?  
dpc (Electrical)
17 May 05 13:42
shkim2000,

I suppose there are probably a lot of other possibilities, but I'd bet a pint of expensive beer that your voltage dip is causing the HPS lamp to extinguish.  This is a well-known "feature" of HID lighting.  Voltage dip causes the output voltage from the ballast to drop below mininum required voltage to maintain the lamp.  A typical 120V HPS fixture will dropout at maybe 100 volts or so.   The real problem is that once the lamp goes out, it takes quite a while for it to re-strike, even if the voltage comes back up immediately.  This is why some HPS luminaires are outfitted with supplemental quartz lamp to provide some light while the HPS lamp is cooling off enough to allow a re-strike.

If the loss of illumination is causing a safety concern, you should add some supplemental lighting, probably incandescent that will not go out during the voltage dip.  Or put in a reduced voltage starter to reduce the dip.  
shkim2000 (Electrical) (OP)
17 May 05 18:24
It is understood that there is no any countermeasure against blackout at the ballast side. Do you expect me to have same problem even if cable size is increased by 2 or 3 times? We can not change motor starter as there are many motors. I have expected that that problem is remedied at ballast side.
Finally, the flood lighting type is changed to other type.
SolderingGunslinger (Electrical)
18 May 05 0:16
The short answer is ...YES.

I sincerely doubt if the I/R drop in the wire feeding the lighting instrument is causing your problem.

Good Luck.

I remain,

The Old Soldering Gunslinger
itsmoked (Electrical)
18 May 05 2:14
Do a study. Turn the motors on in order to find the one that causes the lights to go out and put a soft starter on it.

Soft starters are not expensive and WORK WELL for this type of problem.
analogkid2digitalman (Electrical)
18 May 05 10:47
Could it be possible that the ballast unit is defective? Has it been replaced with a known good ballast?

Could it be an issue with the lamp and not the ballast?

Has the lamp always turned off when the motor starts? Or has it just started recently?

Could the motor and/or it starter developed a problem, thus drawing more current (= > voltage drop) making it appear that the ballast is to blame?

Yes, a lot of questions, but I have not seen any of the above ruled out in the above posts?

Wheels within wheels / In a spiral array
A pattern so grand / And complex
Time after time / We lose sight of the way
Our causes can't see / Their effects.

ftr11 (Computer)
9 Jul 05 4:40
Hello guys if some one need uninterrupted light source
based on any HID lamp such as sodium or metall halide
please look at so called high frequency ballasts, powerd by
a low voltage power line and in parrallel battery source 12VDC or 24VDC.
It is nothing more then switching power supplies.
In this case if you have powerdrop at AC line your lamp
will be nice and sound.
It hapend to me to design staff similar to low voltage
electronic balllasts.  

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