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Cut Bills with Power Factor Correction

POW009 - Power line (1)

How would you react if a bartender gave you a pint of beer that was 50 per cent head? Most beer drinkers want five per cent or less, says Ged Hebdige, technical director at voltage optimisation specialist, Powerdown220, and the same can be said for power factor.

The “apparent power” supplied through the mains by your provider is made up of “active power” plus “reactive power”. Active power is usually referred to as “real power” and is expressed as Watts (W) or Kilowatts (kW). This is the electrical energy that’s converted into work, turning the shaft of a motor, for example, and it’s what the supplier bills you for in kWh.

Reactive power, on the other hand, is used to generate and maintain the magnetic fields surrounding equipment such as motors and transformers. The equipment needs the reactive power to function, but it doesn’t directly go to doing useful work.

Power factor

Power factor is the ratio of active power to reactive power. The more reactive power a facility needs, the lower its power factor. The benchmark is a power factor of 95 per cent, with most users above 80 per cent. However, power factor can be as low as 50 per cent — this means that only half of the power you are supplied goes into active work.

Facilities employing many inductive loads that rely on magnetic fields to operate are most likely to have a reduced power factor. Inductive loads tend to draw current that’s out of sync with the voltage, resulting in a lagging power factor. This is most common with industrial and commercial consumers, where motors and transformers draw heavy loads in a range of applications, such as fans and conveyors.

Suppliers bill consumers for active power, not reactive power. However, they must still supply enough reactive power to meet a user’s demand. A power factor of 50 per cent means the supplier must provide twice as much power as they charge for. Just like a beer drinker wouldn’t expect to pay full price for a pint of beer that was 50 per cent foam, electricity suppliers charge users penalties if their power factor is poor.

Low power factor can also make it harder for a business to expand operations, because the existing supply might not be able to cope with current demand plus the extra to make up for the low power factor. It’s also an important part of power quality, which can affect the lifespan of electrical equipment.

Power Factor Correction (PFC) minimises the amount of apparent power the transmission system must generate. It achieves this by supplying the required amount of reactive power locally, avoiding unnecessary and wasteful power generation and distribution losses.

PFC can cut electricity bills, improve equipment lifespan and might negate the necessity to increase the supply availability or save the costs of uprating or installing a new supply.

Power quality survey

The way to find out if power factor is an issue at your facility is to have an expert conduct a power quality survey. It’s usually possible to predict potential savings to within a few per cent, so a simple calculation tells you if you’d benefit from PFC and how long the payback would take — normally one to three years.

Once power factor is improved, or if your power factor is already within the pint of beer target range of 95 per cent, a power quality survey will also show whether further savings can be made with voltage optimisation (VO) technology. VO may even be a more suitable solution, depending on your business goals around sustainability and energy use.

VO reduces the incoming mains supply voltage to what your equipment is designed to work with. This extends its lifespan, cuts electricity bills by around eight per cent and reduces your carbon footprint.

If a bartender kept pulling pints with too much foam, they’d check their taps. By checking your power quality, you can reduce costs and make sure your facility runs smoothly.

To calculate how you might save with voltage optimisation technology, use our online savings calculator at

Manufacturing & Engineering Magazine | The Home of Manufacturing Industry News

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