POWER FACTOR CORRECTION TECHNICAL


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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


A typical farming application for a PFC 37.5kVAR installation


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.


Reduced emissions


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


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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 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.


Combining technologies 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.


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