PFC capacitors

[guzzi93]

I have a Garage lighting circuit of 17 fluorescent fittings (4x36W 4x30W & 9x56W) connected to two switches, one circuit is ‘star’ connected to a common junction box the other circuit is two ‘star’ connected circuits. The circuit is tripping a 6A MCB, after measuring with an ac clamp meter, I measured just over 7A, when the circuit should be well below 4A.

I am assuming that the PF is causing this and I therefore need to fit PFC to each fitting (easy to fit) Question is How do I connect the PFC capacitors to the fluorescent fittings? Is it in parallel with the incoming supply or in series with the starter? Also what values of capacitors should I use, I can get 2uf and 4uf PFC caps from Maplin for about 50p each.

 

[Lectrician]

I would spilt the circuit.

Flourescents usually have a PF correction capacitor in them anyway, some 'domestic only' types dont.

All fittings that use an inductor (choke) to start the fitting will run at a slight lagging PF, and correcting this is usually too much hastle - every fitting will be slightly different. A single capacitor accross the entire load may improve the situation, and lower your current, but to be honest it is a little slap-dash.

Split the circuit into 2 or 3.