Power Factor Correction

Installation

Maintenance

Remote Monitoring

What Is Power Factor Correction?

Power Factor (Cos φ) is the ratio of True Power (kW) to Apparent Power (kVA) and is used as an indication of how efficiently an industrial or commercial site is operating. The closer the Power Factor is to unity (1), the more efficiently a site is said to be operating. Generally, anything higher than 0.95 is said to be a healthy Power Factor and will usually be sufficient to avoid penalty charges on the electricity bill. However, there are times where it’s essential to operate as close to unity as practically possible in order to keep the current levels to a minimum to avoid tripping breakers on overload.

The presence of Reactive Power (kVAr) on the system leads to a lower Power Factor. Equipment that requires a magnetic field in order to operate (traditional motors, chillers, induction heaters, fluorescent tubes etc) will all draw current that is said to “lag” behind the Voltage; thus producing a “lagging” Power Factor – also known as an inductive Power Factor. The more inductive Reactive Power there will be on the system, the higher the Apparent Power will be and in turn the higher the total current drawn from the network will be.

Reactive Power (kVAr) is the element that Power Factor Correction works to eliminate. The capacitors within draw current that is said to “lead” the Voltage, naturally producing a “leading” Power Factor – also known as a capacitive Power Factor. By having capacitors automatically switched into circuit in equal measure to the nominally inductive site load, the two effectively cancel each other out.

The end result is that the overall Reactive Power levels are decreased and the Power Factor is improved accordingly.

Benefits Of Power Factor Correction

Save Money

Reactive Power Charges and Excess Availability Charges are direct savings you can benefit from with Power Factor Correction equipment. Send us copies of your bills for us to verify them.

Free Up Capacity

Want to expand, but can’t because of limitations on the network supply? Improving your power factor could free up enough capacity to facilitate this without costly upgrades.

Improve Efficiency

Reduced electrical burden on cables, breakers and transformers will extend equipment life and limit the associated downtime to a minimum.

How To Correct The Power Factor

“Surely it’s just a case of checking the kVAr levels on the main meter and finding a suitably rated box of capacitors to install?”

Unfortunately, NO!

That may well have been the way to approach things in the 70’s & 80’s when the only thing network companies cared about was the average lagging power factor over the course of a month. Now, it’s not just lagging, but also a leading power factor that they penalise on. And it’s not over the course of a month either, it’s every half hour period! So not only do we need to be considering automatically switched capacitors to avoid a leading power factor, but we also need to be aware of what the power factor is at at all times to fully eliminate penalty charges – no more monthly average calculations.

“Ok, so it’s a little more complicated now, but can’t we just have a box of capacitors with different ratings to cater for load variations?”

Getting closer, but NO!

That may well have been the way to approach things in the 90’s & 00’s when motors were just motors and when lighting largely consisted of fluorescent tubes. Now, it’s not as simple as just correcting the power factor (that’d be too easy); you’ve also got to consider Power Quality & Harmonics. With the dramatic increase in non-linear loads over the past decade or so, harmonic levels have never been higher. And whether we like it or not, PFC capacitors if not correctly specified, can magnify harmonics and cause underlying power quality issues to be worse.

The Solution: We Can Help

PFC Engineering has been solving power factor correction and power quality issues since 1976. We have the expertise to identify what your PFC requirements are and whether we need to make allowances for high levels of harmonics – in most cases this is done free-of-charge. Whether your sole aim is to make financial savings or if you need to reduce load, here’s how we can help:

  1. Make initial contact with us in whichever way suits you best – we can discuss any problems you’re having, what you’d like to achieve and at this point we can go over any questions you might have.
  2. Send us copies of electricity bills and your half-hourly consumption data for us to carry out an appraisal; both of which are freely available from your electricity supplier. Note: If you’re struggling with this in any way, we can request them on your behalf with signed permission.
  3. We’ll crunch the numbers and let you know how healthy your power factor is at present and what can be done to improve it.
  4. We’ll discuss likely savings with you and then look to arrange a site survey so that we can carry out those all important harmonic checks and look at the logistics of installing new or replacement equipment.
  5. We collate all of the information; costs, savings, recommendations and details of any installation work and put them into a formal quotation for you to consider with no obligation.
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Power Factor Correction Servicing

Already Have Power Factor Correction?

In order to continue to make savings on reactive power and availability charges, we recommend servicing power factor correction equipment at least once every year, sometimes more depending on your reliability on it.

Capacitors can deteriorate over time. The dielectric inside breaks down the more they are switched, the longer they are in operation, and the more external events they’re subjected to. Therefore, keeping on top of the health of your PFC equipment is important to continue to operate at an efficient power factor (>0.95), the level at which charges will start appearing on electricity bills.

It’s even more important if your PFC equipment is detuned. Capacitor deterioration will change the tuning frequency, which can result in harmonic magnification and/or absorption, and subsequently the loss of multiple capacitors in the same bank. The knock-on effect could be power quality issues that can mean other electrical equipment on site is affected.

Find out how we can help take care of the annual servicing of your power factor correction equipment. As part of the service, we offer free reminders for scheduling maintenance visits so that they’re never missed. Contact us to see if we’ve been to your site before and when your service is next due.

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Latest News – Power Factor Correction

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PFC Replacement – Gym, Newcastle upon Tyne

Initial Findings During a maintenance visit, the site’s existing power factor correction (PFC) equipment was found to be in a failed state. The following issues were identified: 4 x 125 A DIN fuses had blown, leaving the system unprotected. …
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PFC Upgrade at Community College, Crawley

During a planned maintenance visit to the college’s LV distribution system, engineers discovered a complete failure of the existing power factor correction (PFC) equipment. All six 25 kVAr capacitor units had failed, and four 100 A DIN fuses…
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Panel Built Detuning Trays for Fresh Food Factory

Following a review of the load at this large UK food manufacturer, it was found that the standard Power Factor Correction equipment was beginning to elevate low levels of background harmonics above 3% VTHD, causing premature failure of the capacitor…
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FS300 Power Factor Unit Install at Brick Factory

We were asked to carry out a service of a Power Factor Correction unit at a Brick Factory near Huntingdon, UK, that had no previous service history since its installation in 2011. During our investigation, we found multiple failures of the…
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PFC Unit upgrade at the supermarket

An end-of-life replacement was required for an old Power Factor Correction unit at a supermarket in central London. A new wall-mountable FS100 PFC unit was to be installed using the existing power and C.T connections. The unit would incorporate…
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PFC Tray Assembly Replacement at Meat Factory.

This 350kVAr Power Factor Correction unit installed in 1998 was found to have multiple capacitor failures following a long period of not being annually maintained. It was decided that an end-of-life replacement for all the tray assemblies…
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PFC Replacement at UK Rubber Manufacturing Plant

We were asked to carry out a full maintenance of a panel built Power Factor Correction unit at a UK rubber fabrication plant. The existing PFC on site had not had a full service before despite being installed in 1997. The unit has a multitude…
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PFC Detuning for a Large Fizzy Drink Manufacturer

After a callout to a significant capacitor failure inside one of the Power Factor correction units, it was noted that the background harmonics had increased since our last annual service visit. A week-long Power Quality Analysis was carried…
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Power Factor Unit Replacement

A recommendation for an end-of-life replacement for a 100 kVAr ABB PFC unit was made following site's annual maintenance due to the age of the existing equipment as well as multiple capacitor failures. We also recommended adjusting the capacitor…

Power Factor Correction FAQs

Power Factor (Cos φ) is the ratio of True Power (kW) to Apparent Power (kVA) and is used as an indication of how efficiently an industrial or commercial site is operating. The closer the Power Factor is to unity (1), the more efficiently a site is said to be operating.

Yes! Reducing your sites Power Factor will in turn reduce the amount of Reactive Charge you maybe being billed for on your monthly electricity statement.

During a annual service of your Power Factor Equipment some of the main tests we carry out are:

  • Microfarad test of the capacitors to check kVAr output
  • Insulation resistance of power cables
  • Manual function tests of contactors
  • Fuse checks
  • Full physical tightness check of all terminals
  • Full clean out of equipment cubicle and vents
  • Full function tests of control relay
  • Check the operation of Fans and quality of filter elements
  • Site Load survey

Other additional tests may be carried out depending on the type of PFC installed on site

The cost to carry out a full Power Factor maintenance will vairy from site to site depending on the total number of PFC units on site as well as the total amount of kVAr. We can provide quotations for individual customers based upon theses factors and our office team are happy to assist with any further questions regarding pricing.

Any questions? Please get in contact, we would love to hear from you.
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