The luminaires should have their power factor stated on the info plate. You can also refer to manufacturers data on their website or via their reselling agents to get the PF or use a test instrument to measure it.
'Correct' power factor would be cos θ equal to 1. For ballasted lighting you'd usually aim for cos θ of at least 0.9 and many discharge light fittings come with built-in power factor correction components to achieve this figure. If it's an old uncorrected ballast then the cos θ value could be as low as 0.5 in which case correction should be fitted.
Leave a comment: