POWER FACTOR

WHAT IS POWER FACTOR

Power factor (PF) is simply the relationship between the active and reactive power on an electricity distribution network and a measure of whether the system’s voltage and current are ‘in phase’. Take, for example, a frothy latte. The coffee body is the ‘active power’ that you can use to do work. The froth on the top is ‘reactive power’; some is useful, but too much is simply a waste the same as the foam you leave behind in your glass.

• If a network is 100% efficient (i-e if no reactive power is present) its power factor (PF) is 1 or unity. This is the ideal for power transmission, but is practically impossible to attain. Variation in power factor is caused by different types of electrical devices connected to the grid that consume or generate reactive power. Unless this variation is corrected, higher currents are drawn from the grid, leading to grid instability, higher costs and reduced transmission capacity
• A poor PF results in additional costs for the electricity supplier
• These costs are passed on to the customer as a ‘reactive power charge’ or ‘exceeded capacity charge’

THE CAUSES OF POOR POWER FACTOR

The causes of poor PF include inductive loads on equipment such as AC motors, arc welders, furnaces, fluorescent lighting and air conditioning. The more inductive loads there are on the network, the greater the possibility there is of a poor PF.

THE BENEFITS OF POWER FACTOR CORRECTION

The following are the main benefits of PFC

• Eliminating expensive utility penalties for a poor power factor
• Improved energy efficiency: reduced system currents and kW losses
• Security of supply: reduction in peak currents prevents fuse failure and loss of supply
• Release additional capacity: to take advantage of the full current capacity available in existing transformers, switch-gear and supply cables
• Increase system load without the need to invest in additional infrastructure
• Environmentally friendly: reduced kWh losses mean that less power needs to be generated, so less CO₂ is produced
• Increased infrastructure service life: since the amount of heat generated within cables, switch-gear, transformers and other equipment is reduced.

Power factor correction equipment is not only fast and cost-effective to install but it starts paying back on your investment immediately, with typical payback times from 12 to 24 months.