What is Power Factor?

Power Factor (PF) is a complex measurement of electrical efficiency. For the more technically minded, a detailed discussion is provided below.   However for those new to the concept, we will now explain in simple and instructive terms what Power Factor is. 

Power Factor is a ratio of the power actually used to produce real work (kiloWatts or kW) for productive output, as opposed to the actual network capacity (kiloVoltAmps or kVA) supplied by the local electricity Distributor to support that same electrical load.   In mathematical terms this relationship can be expressed as follows :

PF = kW / kVA

For example, a customer incurs a Maximum Demand of 500kVA, at which time the real power used is 400kW. The Power Factor can therefore be calculated as follows :

PF = 400kW / 500kVA = 0.80
In other words, 20% of the total kVA demand could be eliminated without affecting production output or plant operation.   From the Distributors point of view, only 80% of the supplied Network Capacity is being utilised, despite being made available and drawn from the electricity network.

Why Correct Power Factor?

The issue of Power Factor has significant operational and financial impacts on electricity Distributors.    For this reason, some Distributors have now introduced “Power Factor” tariffs, or in other words, kVA based Demand charges.

For example, large Low Voltage and High Voltage customers in United Energy and SP Ausnet territories (south east of Melbourne, and Eastern Victoria) are now billed on kVA tariffs, and now pay for the full impact of good or poor Power Factor.    Unlike previous tariffs, the more kVA Demand used, the higher the cost.   

Correcting Power Factor simply means improving the overall efficiency of your electrical system and reducing the Maximum Demand, as supplied and billed by the local electricity Distributor.  Those with improved Power Factor therefore pay less than those with poor Power Factor.  

With improved Power Factor, the local electricity Distributor does not have to install, manage and finance a larger supply capacity to your site. Their operating efficiency is thus improved and their financial investment reduced, and for this reason you are charged less in Demand charges.  However the overall gains in operating efficiency across the entire electricity network is the real payoff for modern Distributors.

Other Benefits to the Customer

As well as reducing your energy bills, Power Factor Correction has other significant benefits:

·Reduced upfront costs levied by the local Distributor to either establish or upgrade supply capacity to the site.
·Reduced capacity of your own electrical assets (switchboards etc.) may defer or avoid all together your own capital and maintenance costs.
·A Power Factor unit can also be the first step toward a wholly integrated Energy Efficiency strategy, and can be electronically linked to an automated Energy Management system.
Our Service

Our engineering and project management capabilities will ensures a tailored seven-step solution for your Power Factor requirements. 

·Analysis of energy bills and Smart Meter data to evaluate the full seasonal Demand cycle
·On-site visit by qualified Engineer to ensure an informed design and quotation in recognition of  site specifics
·Preparation and presentation of a detailed report on current and improved Power Factor, resultant savings, costs, pay-back, warranty, maintenance and technical specifications.
·Negotiation with the local Distributor for a guaranteed Demand reduction in preparation and prior to installation.
·Upon acceptance, installation, testing, commissioning of the Power Factor Unit.
·Follow-Up report on actual Power Factor unit operation and savings.
·Management of optional Maintenance Plan and associated Extended Warranty provision.

Our designs and specifications will achieve a cost effective and quality built installation, that offers reliability, operational flexibility and upgrade capability. And whilst not taking our focus off the price, our aim will always be to ensure the end result is built to last.

More Technical Detail

The Power Factor concept can also be demonstrated by the “Power Triangle”  below:


Where the kVA capacity is the triangle hypotenuse and the kW demand is the adjacent triangle edge.  The Power Factor therefore equals the Cosine of the triangle angle.  

This “Power Triangle” brings into question the other triangle edge, labeled as 300kVAr.   This represents the inductive nature of the electrical load.   Inductance is an electrical term describing the unique impact on current (amps) that inductive loads create. The opposite of inductive load is Capacitive load, or Capacitors.  Capacitors are an essential part of a Power Factor Correction unit, and they effectively eliminate or compensate for a portion of the inductive load, thus reducing the hypotenuse of the resultant “Power Triangle”, as demonstrated below :


As shown, the resultant power triangle has been “corrected” to 412kVA, not 500kVA.  At current tariff rates, this would save over $6000 pa.  Most of our Power Factor projects achieve a 1.5 to 2.5 year payback, however depending on load and site detail, paybacks can vary above and below this tolerance.

Power Factor Correction
If you are a large energy user on a kVA Demand Tariff, or contemplating an upgrade in supply capacity, Selectricity can help you control your Demand and reduce ongoing energy costs by means of Power Factor Correction.