Your switchboard carries your brand. The module inside doesn't.

The Polish panel market competes on delivery, documentation and service — not on sheet metal. The problem appears at one point in the project: choosing the active filter. That is when the brand, the sizing and the responsibility for how the system behaves move to a foreign supplier, and an unfamiliar module ends up inside your cabinet.

1. The invoice says tgφ, not the cosφ from the brochure

Polish DSOs charge for reactive energy above the tgφ limit set in the tariff. For the end user that is a permanent line item; for the panel builder it is a question — what do we compensate it with? A capacitor bank lowers tgφ but does not remove harmonics. On a network with drives, capacitors can resonate with the supply, and the savings turn into blown fuses and overheated reactors.

An active filter does both: smooth reactive compensation and harmonic filtering across the spectrum.

2. New harmonic sources in installations designed a decade ago

PV, heat pumps, EV chargers and LED lighting changed the load profile. The 5th and 7th from six-pulse drives are still there, but higher orders from chargers, even harmonics from asymmetric loads and clear phase imbalance have joined them. Sizing on connected load alone no longer holds — the starting point is a measurement at real load.

3. Three things that change when the module is neutral

Brand. Your name on the door, not the logo of a supplier who sells its own units into the same segment.

Documentation. Type test reports, declaration of conformity, losses and the data needed for thermal verification under PN-EN 61439-1/-2. Without them, the design verification stays on your side — and so does the risk.

Service. Module replacement in days, not weeks. Remote diagnostics instead of a site visit and a flight across Europe.

4. Four questions before the first order

1. At what ambient does the module still deliver full rated current? A closed IP54 enclosure in summer runs 10–15 K above the hall. A module rated at 40 °C is then outside its operating point.
2. Does it filter even harmonics, or only odd?
3. Is EMC tested on the complete unit, or only on the PCB?
4. Who supplies the data for the switchboard's thermal verification?

Sizing starts with a measurement

Send your typical specification — voltage, current, ambient, harmonic profile — and we will return the module datasheet, the derating curve at your ambient and the test documentation. If the numbers do not fit, we will say so.

FAQ

Does fitting an active filter module take thermal verification off my hands?

No. Module losses and the temperature rise inside the enclosure sit within the design verification under PN-EN 61439-1/-2, and that stays with the panel builder. What we can do is supply the input: module losses, the derating curve at your ambient, clearance and airflow requirements, mounting distances. With the data, verification is a calculation. Without it, it is a guess.

The module is rated at 40 °C. Can it still deliver full current when the enclosure reaches 55 °C in summer?

No — it runs on the derating curve. Size against the temperature inside the cabinet, not the temperature in the hall: a closed IP54 enclosure typically runs 10–15 K above the hall in summer. Fix the internal temperature first, then read the available current at that temperature, instead of matching nameplate current to load current.

Does it filter even harmonics, or only odd?

Conventional active filters are designed around odd orders; that is the norm across the industry, not a weakness of one supplier. Even harmonics come from half-controlled and asymmetric loads, and phase imbalance is a separate issue again. Whether a given model handles them depends on its control algorithm and capacity allocation and should not be assumed. If your site shows a visible even-order component, send us the spectrum at sizing stage.

When is an active filter the only option, and when is a capacitor bank enough?

Four situations normally settle it: heavy drive, rectifier or UPS load with harmonics already over the limit; a capacitor bank that has started blowing fuses, overheating reactors or swelling capacitors — the classic resonance signature; load that fluctuates enough to need stepless compensation rather than switched steps; and a cabinet that has to do reactive power and harmonics at once. Where the load is stable and the network is clean, a capacitor bank is still the cheaper answer, and we will say so.