Harmonic Filter Design Active
Specification of active harmonic filters, which measure the distorted current and inject a cancelling waveform in real time. They handle variable spectra and changing load in a way passive filters cannot, at higher capital cost and with their own commissioning and tuning requirements.
What this study establishes.
Compensation current sizing per harmonic order, from measured spectra across the load range.
Unit rating and quantity selection with headroom for load growth.
Placement analysis — central at the incomer versus distributed near dominant sources.
CT specification and placement, which determines whether the filter can see what it must cancel.
Expected residual distortion after compensation, stated by order rather than as a single figure.
Commissioning and verification plan with before-and-after measurement.
What the work covers.
Specification of active harmonic filters, which measure the distorted current and inject a cancelling waveform in real time. They handle variable spectra and changing load in a way passive filters cannot, at higher capital cost and with their own commissioning and tuning requirements.
Active filters are sized in compensation amperes, not in kVA of load. Sizing from load rating rather than from measured harmonic current is the usual specification error and produces a unit that saturates at the orders that matter most.
What lands in your inbox.
Compensation current sizing per harmonic order, from
Compensation current sizing per harmonic order, from measured spectra across the load range.
Unit rating and quantity selection
Unit rating and quantity selection with headroom for load growth.
Placement analysis
Placement analysis — central at the incomer versus distributed near dominant sources.
CT specification and placement, which determines whether
CT specification and placement, which determines whether the filter can see what it must cancel.
Expected residual distortion after compensation, stated by
Expected residual distortion after compensation, stated by order rather than as a single figure.
Commissioning and verification plan
Commissioning and verification plan with before-and-after measurement.
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 spectra across the full operating range, including worst-case orders; load variability profile — active filters are sized on compensation current, not load kva; available space, cooling and.
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 519-2022, IEC 61000-4-7, IEC 62477-1, 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: spectrum is broad or variable, making tuned passive filtering impractical; load changes frequently, or future load composition is uncertain; space or resonance constraints rule out passive filtering. 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 spectra across the full operating range, including worst-case orders; load variability profile — active filters are sized on compensation current, not load kva; available space, cooling and switchgear position for the unit. Where any of it is missing we can establish it on site, which changes the scope rather than blocking the work.
Primarily IEEE 519-2022, IEC 61000-4-7, IEC 62477-1, IEC 61000-3-6. 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.