Fluoro Light Wiring

[SpidersWeb]

Hey guys and girls,

Got everything I need to finish up my hood wiring (5 x T8 36W), but was just interested in one point. The diagram below is drawn on the ballast itself, all makes sense to me, except the finer points of the capacitor marked '??'.

Is this to filter the incoming current, or for noise suppression? How do I work out the correct capacitance for this? I know this capacitor is optional, but would like to wire everything up properly if possible.

Thanks

[Ira]

I always thought it was to store the big surge of electricity needed to light off the tubes when the starter triggers.

[SpidersWeb]

hmm that does make sense

Also found an old ballast (same purpose and brand, just older) and it mentions the capacitor on it, it says:

P1 0.8 use 3.2uF

P1 0.9 use 3.9uF

but I dont know what the 0.8 or 0.9 is.

Also here is the caps on an existing setup, it works, but I didnt put it together, I found it unusual how the caps were connected to the earth like that, but I never quite got that far in to electronics unfortunately

and the new ballast is:

[SpidersWeb]

heh turned out these ballasts have an online manual

http://www.tridonicatco.co.nz/MEDIEN/CAT0304_AU/MagBal.pdf

The size needed for this model of ballast is 4uF.

The reason why its recommended (not needed) is on the third page of this http://www.tridonicatco.co.nz/Medien/cat0304_au/Capacito.pdf. Basically stabilises power consumption by 'cancelling the lag effect of inductance, increasing the power factor closer to unity'

So the P numbers above were saying basically use 3.2uF for a 0.8 power factor, or 3.9 for a 0.9 power factor, the closer to 1 the power factor is the more efficent? *shrug* ok it's a bit beyond me, but at least I semi-understand what its for and what I need.

Its the Power Factor Correction Capacitor :roll:

[Zev]

Power Factor Correction is probably not an issue if you only have a few Fluorescent fittings, and don't pay for your power on peak demand.

If, on the other hand you have a humungous fish room with several thousand fittings switching on at once, it could be a concern.

Domestic users do not normally pay by peak, but your power provider probably does.

Most power providers like to see PFC at around .9, and will penalise larger consumers (ie industrial consumers) for being lower by charging them more.

The lower your PF, the more power is consumed. It's all about VoltAmps and Watts.

This is dredging through long distant and easily forgotten theory in my brain, and I hate maths, so it's a rough outline of what PFC is about.

[AMAZONIAN]

Hi

The RED twin capacitor thing in your post is NOT THE ONE IN THE DIAGRAM ON THE BALLAST.

That is a suppression only Capacitor.

You need a SPECIFIC FLOURESCENT Capacitor ( FROM MASTERTRADE) the rating of the capacitor should be ideally 4,0ufd for a single 20w tube

and 6.0ufd for a single or twin tube intallation using a 36w Ballast.

The flouro will work perfectly normally without the capacitor.

Yes it is to do with PFC, but also has another job and that is aiding in discharging the tube at turnoff, which prevents what is known as ghosting.

This occurs when the light is turned off and has a residual eerie glow for a while after.

This is also from a Registered / Liscensed Electronics Engineer..... Me

[Ira]

This occurs when the loght is turned off and fas a residual glow for a while after.

Cool, I'm tempted to remove the caps from my lights...

[richms]

I took the capacitors out of all my fittings here because they eat X10 signals. I dont get any ghosting on turnoff.

Also you need to remove them if you want to dim fluros since dimmers can only support a tiny amount of inductive load