The techs factor
With rising energy costs and the drive towards net-zero greenhouse gases by 2050 influencing tax policy, there’s never been a greater need for energy efficiency. Gary Vizard, Managing Director of industry experts EnergyAce, explains why technology like power factor correction could be one answer
Power factor correction (PFC) has been around since the turn of the 20th century and improves the overall efficiency of an electrical supply by the controlled introduction of capacitors on to an electrical system.
Power factor is basically a degree of electrical efficiency. In an AC circuit, it’s the ratio between the useful power kW (true power needed to perform a task) and apparent power kVA (a combination of true power and reactive power, i.e. power drawn in addition to useful power but does not contribute to the task).
Power factor is displayed as a figure between 0.01pf to 1.00pf, with a poor power factor generally understood to be less than 0.95pf and a perfect power factor as 1.00pf, known as unity. In layman’s terms, you could describe power factor as a % degree of electrical efficiency and a good power factor in excess of 95% is normally deemed as electrically efficient. Power factor can also be termed as lagging or leading.
A lagging power factor signifies that the load is inductive and in need of correction through the introduction of capacitors, while a leading power factor signifies that there is too much capacitance in circuit.
A general methodology exists between the network operators (DNO) to apply penalties to users whose power factor falls below 0.95pf either lag or lead, which appear on a user’s electricity bill in the form of a reactive power charge.
Poor power factor can create a number of negative effects in both billing and infrastructure. In fact, a European survey in 2007 discovered that poor power quality is seriously affecting business results in the industrial and service sectors, with an annual total loss of €150 billion across Europe. To counter this, installing PFC can offer significant benefits as follows:
Removal of reactive power charges
Targeting unity power factor and ensuring 0.95pf or better will, in most cases, remove the reactive power penalties on electricity bills completely.
Reduction in authorised supply capacity
Authorised supply capacity charges (availability charges) are normally charged in kVA at a typical rate of £1/kVA/month. The charge relates to the maximum demand or maximum power drawn from the network on a user’s site and is generally in place to pay for the supply network infrastructure required to deliver the declared (or drawn) degree of energy at any time, night or day. A penalty charge for energy drawn over and above this declared or agreed supply capacity is typically twice the cost. Power factor in an AC power circuit is directly related to kVA and associated circuit currents, therefore an improvement in power factor would normally allow the user to target the correct/lower capacity level to avoid exaggerated charges on monthly energy bills and allow for additional loads to be introduced on an otherwise overloaded system.
Reduced kw/h consumption
Reduced kw/h losses in power cables, switchgear and supply transformers deliver benefits to the whole electrical system.
Higher, inefficient energy consumption inevitably results in an increase in CO2 emissions and associated penalties – something that can be reduced with PFC.
Reduced investment in infrastructure and costly network upgrades
A site operating on a power factor close to unity would require less investment in associated power plant, e.g. transformers, switchgear and cables, as the reduction in kVA will allow for the investment in associated plant to be minimised. Investments into costly network upgrades due to an overloaded electrical supply can be avoided by improving power factor at a fraction of the cost of an upgrade.
Improvement in power quality
The reliability and consistency of an electricity supply is critical to many energy users. Poor power factor can create undesirable issues and poor reliability on a user’s power network – things that PFC can help to resolve.
Installation of PFC is carried out in parallel with the main supply to offer ‘bulk correction’ and is connected just like any other machine via a suitably rated form of protective device like a molded case circuit breaker (MCCB) or fused switch. Individual ‘local’ power factor correction capacitors can also be installed on individual motor loads.
When installing on individual motor loads, it is important to ensure over-compensation cannot occur and that any associated controls will allow for the capacitor to discharge between energisation periods.
PFC can be combined with other technologies like voltage optimisation and/or remote metering and monitoring to offer additional befits. Voltage optimisation is a complementary technology and works very well in synergy as a powerful energy saver that is extremely visible on energy bills.
A combined approach introduces the best of both technologies to reduce energy consumption, carbon emissions, capacity and availability charges, remove reactive power penalties, improve supply utility and protect electrical equipment from high voltage levels.
The first stage of any energy reduction scheme is to gather accurate information and data on existing energy consumption and efficiency. Combining this with remote metering and monitoring enables users to monitor energy consumption and target reductions – a fundamental step when targeting energy reduction, irrespective of business size or sector.
Saving energy and money
EnergyAce has been manufacturing energy savings solutions since 2002 and works mainly with partners to deliver PFC, voltage management and remote metering systems in the UK.
One such partner is Dave Purves of SELECT Member business WP Purves Electrical Ltd, based in Coldstream, Berwickshire.
Dave has been delivering Energy Ace to agricultural, commercial and industrial clients to save energy, reduce demand and reduce CO2 liability.
He told CABLEtalk: “I first got involved with PFC about four years ago through an agricultural customer who wanted to do something about his huge energy bills. He’d read about PFC and contacted Energy Ace, who then approached us to carry out the installation.
“It was fairly straightforward project – the only thing you have to be aware of at first is sizing the correct protective device, but after that it’s just a case of choosing a mains switch fuse or an MCCB, and then connecting it in parallel into the system. It really is that simple.
“Since that first job, we’ve gone on to do about 25 similar installations, so it’s given us a steady amount of work.
“We work in the commercial, agricultural and industrial sector, so there are lots of people who have an issue with using a lot of power and want to do everything they can to counteract it. In most places, PFC can provide a significant reduction, although you do need to be using quite a bit of load in the first place to see a difference. But for those who are, it’s very effective.
“For example, on that first job we put an amp meter on the incoming tails when it was switched off and when we switched it on the difference was incredible – the customer went on to cut his bills by a third.
“It also seems to work well with renewables, because you’re able to feed more back into the grid by maximising what you’re producing. And if you combine it with voltage optimisation, it makes an even bigger difference.
“It’s definitely something that’s worth investigating if your customers are heavy users – I’ve been very impressed.”
EnergyAce can advise on every aspect of PFC, helping organisations identify energy wastage and make better, more informed decisions. For more information, contact EnergyAce on 01695 559 785, email firstname.lastname@example.org or visit www.energyace.co.uk