Harmonic Filter Design Passive
Design of tuned passive filters — a reactor and capacitor branch resonant near a target harmonic — sized to absorb distortion at specific orders. Passive filtering is economical and robust, but it interacts with the supply impedance and must be designed against the measured system, not a generic assumption.
What this study establishes.
Filter branch design per target order, with reactor and capacitor ratings and detuning factor.
Frequency scan of the system with the filter connected, confirming no new resonance is created.
Filter loading check under existing background distortion, including utility-side harmonics.
Reactive power contribution of the filter and its effect on site power factor and voltage.
Protection and switching arrangement for the filter branch.
Performance prediction against the applicable limit, with the operating regime stated.
What the work covers.
Design of tuned passive filters — a reactor and capacitor branch resonant near a target harmonic — sized to absorb distortion at specific orders. Passive filtering is economical and robust, but it interacts with the supply impedance and must be designed against the measured system, not a generic assumption.
A passive filter is a low-impedance path at its tuned frequency for the whole network, not just for the site's own load. Where background utility distortion is significant, the filter absorbs that too and can overload on harmonics the site never produced.
What lands in your inbox.
Filter branch design per target order,
Filter branch design per target order, with reactor and capacitor ratings and detuning factor.
Frequency scan of the system
Frequency scan of the system with the filter connected, confirming no new resonance is created.
Filter loading check under existing background distortion
Filter loading check under existing background distortion, including utility-side harmonics.
Reactive power contribution of the filter and
Reactive power contribution of the filter and its effect on site power factor and voltage.
Protection and switching arrangement for the filter
Protection and switching arrangement for the filter branch.
Performance prediction against the applicable limit,
Performance prediction against the applicable limit, with the operating regime stated.
How we run it.
Scope & data capture
We confirm the question the study must answer, agree the measurement or modelling points, and collect what the work depends on: measured harmonic spectra and the system impedance at the connection point; background distortion from the utility, measured with site load off where possible; existing power factor correction.
Measurement & modelling
Engineers carry out the measurement and modelling on site and in software, under operating conditions representative of the problem rather than a single convenient snapshot.
Analysis against standard
Results are assessed against IEEE 1531, IEEE 519-2022, IEC 61642, with the assessment basis and any measurement uncertainty stated rather than implied.
Report & recommendations
You receive a signed engineering report with findings ranked by consequence, the reasoning behind each conclusion, and mitigation options costed so they can be acted on or deferred deliberately.
Assessed against the published limits.
Common questions.
Typically in one of these situations: distortion is dominated by one or two specific orders, typically 5th and 7th; existing capacitor banks are failing and need detuning rather than replacement; a cost-effective fixed solution is preferred over an active one. If none of these apply, the study is unlikely to be the right next step and we will say so.
To scope and run the work we need measured harmonic spectra and the system impedance at the connection point; background distortion from the utility, measured with site load off where possible; existing power factor correction equipment details. Where any of it is missing we can establish it on site, which changes the scope rather than blocking the work.
Primarily IEEE 1531, IEEE 519-2022, IEC 61642, IEC 60871-1. The applicable framework depends on your connection agreement and jurisdiction, so we confirm which applies before measurement rather than after.
Ready to start the engagement?
Tell us about your site and the problem you are seeing. We come back with a fixed scope, a fixed fee, and a named lead engineer.