Power Quality » Power Factor Overview
Understanding Power Factor
Power factor is a term used frequently in the energy industry, but you may be looking for more details to understand exactly what it is and why it’s relevant. We’ll go through the whats, whys, whens, and hows in this article to try and clear things up for you.
What Is Power Factor?
Power Factor (PF) plays an important role in your site’s power quality. PF gives an indication of equipment on site requiring magnetic and electric fields for their operation.
PF is affected by the amount of reactive power on site, most often by inductive loads such as pumps, fans, motors, air conditioning units, and other heavy machinery. Specifically, PF is the ratio between 0 and 1 of real power (kW) to apparent power (kVA), where 1 is optimal.
In an analogy for apparent power, a glass of draught beer is made up of two parts: liquid beer and head. While a bit of head is ok, when there’s too much you’re getting less beer, in the same way that you could be paying too much for your apparent power when the site’s reactive power is too high. The greater the reactive power, the lower the power factor.
Why Is It Important?
A low power factor can have a big effect in how much you pay on your electricity bills.
Demand or capacity charges typically make up a large portion of your electricity costs already, as a result of the major impact that it has on upkeep and upgrades of the electricity grid. For more general information on demand, please read through our article on Understanding Electricity Demand.
Sites with low power factor due to high reactive power requirements place a greater strain on the electricity grid. This is because these requirements has a direct effect on the physical infrastructure, requiring a larger pipeline to deliver power to the site.
When Is It Important?
For larger customers, the network costs of maintenance and supply to customers with high reactive loads are reflected on the network portion of electricity invoices, via a $/kVA/day rate. PF is usually ignored for small customers who just pay for kWs, which is why its important to see if kVA appears on your invoices to see if it’s relevant.
If you’re paying for kVA, next it’s good to look at your site’s typical demand magnitude. On your invoice, make sure the average capacity charge is at least 150 kVA. A good payback will be achieved when a high demand is combined with an existing low power factor. The invoice may also specify the peak periods for the network tariff.
It’s important to keep in mind the time of day when looking at PF. Your particular network tariff will specify the time period when peak demand/capacity is calculated. For example, many Ausgrid tariffs take the highest demand experienced between Mon-Fri 2-8 PM for their capacity charge. Anything seen outside of these times is irrelevant for PFC savings in this network.
Use EnergyLink to Check Yours
From within EnergyLink, within the Analyse Data page, you can choose to view Power Factor from the measurement points menu for the selected meters.
While the first example shows a well-performing site, the low PF of the second example indicates that it could be a good candidate for a PFC unit. More information can be gained by looking at reactive power to quantify the reactive power loads on site.
Power Factor Correction Summary
A power factor correction (PFC) unit is used to improve your site’s energy efficiency by offsetting the reactive power loads on site. Using a bank of capacitors, the electricity network is buffered from the site’s equipment.
A PFC unit can help to reduce your electricity charges when tariff appropriate, as well as boost site energy efficiency to reduce strain on the electricity network and the site’s equipment.
For more on PFC benefits, recommendations, and troubleshooting, please stay tuned for our upcoming Power Factor Correction Article.