Reactive power

Some Distribution Network Operators (who own and manage the electricity distribution cables) have introduced charges for Reactive Power consumption.

These Reactive Power charges can be reduced or eliminated by installing Power Factor Correction equipment at your site. If you’d like an advisor to arrange an assessment through our provider, please call 0845 070 9494 (view call charges).

What is Reactive Power?

Not all power used by electrical equipment is 'useful', i.e. it is not used by the equipment to create outputs. Reactive Power is a measure of this 'unproductive power'.

In most electrical circuits, Reactive Power comes from the creation of an electro-magnetic field necessary in motors and transformers. This impedes the electrical current, causing Reactive Power to be required. For a full explanation please see our Guide to Reactive Power (PDF, 0.12MB), or the following analogy helps explain reactive power in simple terms:

Imagine a horse pulling a barge along a canal. The horse is pulling the barge from the towpath, as he cannot stand directly in front of the barge. Some of the force on the towrope is 'useful', i.e. it is pulling the barge forwards along the canal. However, some of the force is pulling the barge in towards the canal bank and not in the direction the barge is travelling. This sideways force is unproductive. Reactive Power can also be thought of as ‘unproductive’ or ‘useless’ power.

Why is Reactive Power consumption charged?

If a site has high Reactive Power, more current has to flow to provide the same output. This means more capacity has to be provided, potentially increasing costs for the Distribution Network Operator.

Will my Reactive Power charges ever be estimated?

Some Distribution Companies charge for Reactive Power on a estimated basis where no data is received from the customer's meter - their calculation is based on an assumed Power Factor taking consumption for the period into consideration. The lack of actual data could be due to the configuration of the meter, or even because the type of meter installed at your property does not register Reactive Power. Where npower receive an estimated invoice we will be obliged to use that information to recover the costs incurred at your site.

npower are looking into ways to reduce the number of estimated Reactive Power charges in the future including arranging for a meter exchange or reprogramming the meter, at no cost to you.

How can these charges be reduced?

Given Reactive Power arises from the electrical properties of equipment on site, further equipment can be added to amend the electrical properties and reduce or eliminate Reactive Power charges. This is known as Power Factor Correction equipment. The cost of the equipment, including installation, will typically fall within the range of £1200 - £16,000 depending on specific site requirements plus an initial site survey, costing £400.

If you feel it may be commercially viable, npower business can provide the expertise to assess the need for Power Factor Correction equipment and arrange the smooth installation of equipment. Just call 0845 070 9494 (view call charges).