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Why would you want a high power factor?

A power factor (PF) only exists in AC applications, not in DC. It shows how well the voltage and current waves are in sync. With a resistive load like a heater or an incandescent bulb, we have the maximum of PF=1, meaning voltage and current are in sync.

Switching power supplies or other capacitive or inductive loads cause a shift between current and voltage. As a result, a device with a power factor lower than one needs more current to provide a certain amount of power. This causes trouble to electricity providers, so for a number of years most countries have established rules demanding that devices with high power consumption (like computer power supplies) must also have a high power factor.

The same applies to lighting. Bulbs with very low power consumption (<5W) are usually exempted, but for all other bulbs and luminaires a high power factor is recommended. To do our share in improving the stability of the electricity grid, Yuehsin Electronics is striving to exceed the required power factor in all relevant products, and you as a consumer can do your share too, by checking the specifications the next time you buy a bulb or luminaire, and reject one with a low (for example PF<0.65) power factor.