Power factor correction to help lessen load

15th April 2016 By: Simon Sonnekus - writer

The rise in electricity costs and the drop in commodity prices have led businesses across the industrial and commercial spectrum to look at how their electrical equipment converts electric current into useful power output in order to save on power by making use of power factor correction (PFC), says harmonic filtration solutions supplier Alpha Power Solutions.

“Companies such as sawmills, flour mills and plastic extrusion and recycling industries, along with industries that use machine tools, stamping machines, welders and compressors, foundries and mining units, fast-moving consumer goods industries, bottling plants, agricultural customers, large industrial and commercial customers can benefit from the use of PFC and maximum demand equipment,” says Alpha Power Solutions MD Eric Solot.

He explains that PFC refers to the process of improving the low power factor of a power system by means of installing PFC capacitors and, in so doing, increasing the ratio of active power to apparent power.

Solot adds that, when the apparent power is greater than active power, then the utility provider must supply the excess reactive power and working power. Power capacitors act as reactive power generators and reduce the total amount of current a system draws from the grid.

“The reactive power consumed by an opera-tion can be generated through capacitors rather than from the grid. “The on-site generation of reactive power to reach maximum demand will subsequently lower the amount of electricity that is required from the power utility,” Solot says.

He notes that, while lower energy costs remain the short-term benefit of power correction, in the long run, companies can free up capacity on their electricity supply, which allows companies to add more equipment and, in so doing, increase production or avoid relocation to different premises with a larger power supply.

“By reducing the total current drawn from an electrical distribution network, as well as ensuring electrical equipment effectively converts electrical currents supplied by the power utility, PFC improves useful power output while saving on electricity costs.”

Solot notes that the rise in tariffs has allowed an increase in return on investment for companies looking into the use of PFC for production. He explains that, while accurate measurements of the electrical load profile of a potential customer are required to determine the most cost-effective power factor correction solution, payback periods can vary between 3 and 18 months.

“Electricity has until recently been a cheap commodity in Southern Africa, in general. “The payback period of an investment in power factor correction has therefore been fairly unattractive. “Recent tariff hikes have significantly reduced the payback periods and will continue to do so in the short to medium term. PFC equipment of good quality has a life expectancy of at least ten years,” he states.

With the help of a comprehensive energy audit, companies will be able to establish the extent to which they can use PFC to their benefit. Solot notes that the collation of information gathered from sophisticated test equipment, which is installed on-site, along with the review of historical billing information and custom designs, which take space, ventilation and other logistical factors influencing the effective installation into account, results in the most efficient and lowest life cycle costs of PFC interventions.

Private Use and Fines

Solot states that power utilities in industrialised nations charge industrial users a penalty when their power systems’ power factor drops below the level of 0.90. This power factor surcharge covers the electric utility’s cost of supplying the power system with additional reactive power.

In South Africa, no fines are imposed as yet, although Solot emphasises that Eskom intends to introduce fines in the near future, albeit under an alias of the power factor surcharge, which was implemented by Zambian State-owned power utility Zesco in 2014.

“Some South African municipalities like City Power do charge for excessive reactive power consumed. “City Power charges for all reactive power consumed below a power factor of 0.96.”

While more companies are looking into PFC solutions to lower electricity costs, Solot emphasises that PFC for private use does not yield any savings.

“The addition of PFC may reduce the current drawn by a residence, but this will not result in a reduction of electricity costs. “This is because consumers are only being billed for active power consumption and not for maximum demand, nor for reactive power consumption,” Solot explains.

He adds that PFC in a residential application is primarily only used to prevent the main incomer circuit breaker from tripping by reducing the total current drawn. The power factor correction panel supplies most of the reactive current drawn by the inductive components in the residence and, in so doing, reduces the total current flowing through the incomer circuit breaker.

“There is no financial benefit in doing so – there is only a comfort benefit. “Installing a PFC system in a residential area would be paying for a product that is already pro- vided at no extra cost,” concludes Solot.