Reactive power - in plain English
Some equipment in a company - motors, transformers, welding machines, old lighting, power supplies - in addition to the energy that does work (active), "pumps" reactive energy through the grid: needed to generate magnetic fields, but doing no work. It circulates between the plant and the grid, overloading it - which is why the distribution operator monitors the ratio (power factor) and adds charges when reactive energy consumption exceeds the agreed level or when the plant feeds capacitive reactive energy back into the grid.
Where to find it on the invoice
On the invoice for distribution (not for energy sales), look for items like "exceeded inductive reactive energy" or "capacitive reactive energy". For some companies this is several dozen zł a month, for others - thousands. Characteristically: the amount can grow after changes in the plant, e.g. after replacing lighting with LEDs or installing inverters, because modern electronics more often "feed back" capacitive reactive energy - and charges are also billed for this.
How it is fixed
- Invoice analysis - 12 months back shows the scale of the problem and seasonality; often already at this stage it is clear whether the topic is profitable;
- Measurement at the facility - we record grid parameters during the normal operating cycle of the plant (day-week); this determines what generates reactive energy and of what type;
- Selection of compensation - most often a capacitor bank with automatic regulation, in facilities with a predominance of electronics - reactors or mixed compensation; choosing "blindly", without measurements, is a straight 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 companies. The principle is the same as in all our work: first measurement, then selection.
When is it worth taking care of this
- the "reactive energy" item appears on the invoice every month - this is a fixed cost that can simply be turned off; quite often the investment pays off in the first year;
- the plant is planning an expansion or increasing connection capacity - sorting out reactive power is often cheaper than ordering more capacity;
- machines reset or inverters report errors - this is a broader topic, power quality, but it often comes up during the same analysis.
5-minute test: take your last distribution invoice and look for the word "reactive". Is it there and has a non-zero amount? Send us the invoice - we do the initial analysis based on documents before we propose anything.
