Power Factor

Power Factor (HPF, LPF Lead Lag)
This is the relationship between an alternating Voltage & current in a circuit. In a resistive circuit (eg heater, toaster, electric cooker) the current is in phase with the Voltage. However, some devices with magnetic components in the circuit (eg ballasts) alter the phase relationship which causes extra current to be drawn for the same power output. Ballasts (being inductive components) cause the current to lag behind the voltage.

Eg: A 240 Volt, single 36 Watt fluorescent fitting:

LPF: Current = 0.43 Amps
HPF: Current = 0.21 Amps

In both cases the power produced is the same, and the current difference is caused by different power factor figures.

The extra current can be a problem for the building wiring and circuit breakers in situations where there are a lot of fluorescent luminaires. To bring the power factor back to nearly the same as it would be in a resistive load we add capacitors to fluorescent luminaires. These are called High Power Factor fittings.

Power factor correction capacitors can also be fitted in the power distribution board instead of on each fitting.

Some states use lead / lag fittings. These are twin lamp types with one lamp having a leading power factor (current leading voltage) and one lamp having lagging power factor. Single lamp fittings of this type are call leading power factor (capacitor in series with ballast).

Blocking Inductor
This an inductor (coil) wired in series with a fitting to present a high impedance to ripple control frequencies. When a power factor correction capacitor is included in a fitting (HPF models) it presents a low impedance to the ripple control frequencies. This reduces the level of these frequencies and degrades the reliability of ripple control systems. The addition of an inductor blocks the ripple control frequencies from reaching the capacitor and prevents them from being reduced in amplitude.

EMC
Since January 1, 1999 Australian regulations have required that all light fittings comply with regulations concerning the amount of electrical interference produced by the fitting. This is of special concern to fluorescent fittings as they generate considerable interference (mainly from the lamp). All ndLIGHT fittings comply with these regulations and have the C tick approval.