Reactive power — in plain language
Some devices in a company — motors, transformers, welders, old lighting, power supplies — in addition to the energy that performs work (active), "pump" reactive energy through the network: needed to generate magnetic fields, but not performing work. It circulates between the facility and the network, burdening it — which is why the distribution operator monitors the proportion (power factor) and adds charges when reactive power consumption exceeds the agreed level or when the facility returns capacitive reactive power to the network.
Where to find it on the invoice
On the distribution invoice (not the energy sales invoice), look for items such as "excess inductive reactive energy" or "capacitive reactive energy". For some companies, this is a few dozen zł per month, for others — thousands. Characteristically: the amount can increase after changes in the facility, e.g., after replacing lighting with LED or installing inverters, because modern electronics more often "return" capacitive reactive energy — and charges are also calculated for this.
How it is fixed
- Invoice analysis — 12 months back shows the scale of the problem and seasonality; often at this stage, it is clear whether the topic is worthwhile;
- On-site measurement — we record network parameters during the normal operating cycle of the facility (day-week); this determines what generates reactive energy and what type;
- Compensation selection — most often a capacitor bank with automatic regulation, in facilities with a predominance of electronics — chokes or mixed compensation; "blind" selection, without measurements, is a straightforward path to oversizing or resonances;
- Control measurement after installation — confirmation of the effect on the meter and on the invoice.
We describe the entire process on the page reactive power compensation for businesses. The principle is the same as in all our work: first measurement, then selection.
When is it worth addressing?
- The item "reactive power" appears on your invoice every month — this is a fixed cost that can simply be switched off; it is not uncommon for the investment to pay for itself in the first year;
- The plant plans an expansion or power increase — managing reactive power is often cheaper than ordering more power;
- Machines reset or inverters report errors — this is a broader topic, power quality, but it often comes up in the same analysis.
5-minute test: take your last distribution invoice and look for the word "reactive". Is it there and does it have a non-zero amount? Send us the invoice — we perform an initial analysis based on documents before proposing anything.
