Power factor is the measure of how efficiently you use the electrical equipment on your premises. Running your electrical equipment at the best power factor ratio can help keep your energy costs down. Here we will explain further how power factor affects your energy bills and what you can do to correct it.

What is the difference between Working Power and Reactive Power?

Power is split between Working Power and Reactive Power. Working Power is used in all electrical appliances to create such things as heat, light and motion. This power is measured as kW or kilowatts.

Reactive Power (kVArh) is the difference between Working or Active Power and the Total Power consumed. Some electrical equipment used in industrial and commercial buildings requires an amount of ‘reactive power’ in addition to ‘active power’ in order to work effectively.

Reactive Power generates the magnetic fields which are essential for inductive electrical equipment to operate, especially transformers and motors. This load is measured via the reactive register on your half hourly meter.

The Working power and Reactive Power of your equipment makes up your Apparent Power, measured in kVA. Power Factor is the ratio of Working Power to Apparent Power.

What is Power Factor and how is it caused?electricity surge

Power Factor is the relationship between ‘Active’ and ‘Reactive’ Power and indicates how effectively electrical power is being used:

Bad power factor – is low (less than 0.95) so more Reactive Power is required.

Good power factor – is high (greater than 0.95) so power is used more effectively.

‘Perfect’ power factor – (1.0) this is known as unity and does not use any Reactive Power.

Most electrical equipment, such as motors, compressors, welding sets and even fluorescent lighting, create an inductive load on the supply. An inductive load requires a magnetic field to operate, which then causes the electrical current to “lag” the voltage – i.e. the current is not in phase with the voltage.

How is Reactive Power charged on my energy bills?

Reactive power is charged according to the accumulated volume on your reactive register.

These charges will also vary depending on two elements:
1. Contract type
2. Local Network Operator charging methodology

Contract type

If you have a fully inclusive contract, you will pay the rate which you agreed to on your contract. If you have an energy only (supply only) contract, you will pay the rate which has been passed through from your Local Network Operator; which may change if they alter their charging methodology.

Local Network Operator charging methodology

Local Network Operator charging steps differ depending on the location of your site in Great Britain and who serves your network. See the table below.

Where the first step excludes a percentage figure, the Local Network Operator does not currently charge for reactive power.

Where the first step is 33%, the Local Network Operator does not charge for reactive power for the first 33% of units (kWh). Charges therefore apply when the difference between the total units recorded on the reactive register (kVArh) is less than 33% of the total units consumed (kWh).

Where the first step is 50%, the Local Network Operator does not charge for reactive power for the first 50% of units (kWh).

Charges therefore apply when the difference between the total units recorded on the reactive register (kVArh) is less than 50% of the total units consumed (kWh).

For example:

Where a meter consumes 2,500 kWh and 2,000 kVArh, reactive charges would be applied on 1,175 units if the charging step was 33% or 750 units if the charging step was 50%:

33% charging step

2,500 kWh x 33% = 825 units 2,000 kVArh – 825 = 1,175 chargeable units

50% charging step

2,500 kWh x 50% = 1,250 units 2,000 kVArh – 1,250 = 750 chargeable units

If reactive power charges are applicable for your site, they will appear within the ‘Consumption charges’ section of your bill. The table above shows the specific charges for different Local Network Operators.

What can I do to avoid reactive power charges?

To avoid reactive power charges, you can install Power Factor Correction equipment. We use a wide variety of products, some of which operate automatically, that compensate for varying electrical loads. This situation is common in today’s manufacturing plants and offices and we are ideally placed to help you improve the way you utilise your electricity supply. Our experienced engineers will assess the demands placed on your supply and identify and correct areas where power has been lost. Power Factor Correction equipment improves efficiency so that less electrical current is needed to achieve the same result.

With our reputation for integrity and our high levels of customer care we can help you make your power supply as efficient as possible.

If you are interested in a quotation to install this equipment, please Contact Us