THD Compliance Assessment
A focused compliance verification against a stated distortion limit — a utility connection condition, a lease clause, a specification or an internal standard. Narrower than a full harmonic study: the question is pass or fail against a defined limit at defined points.
What this study establishes.
Measurement at the defined compliance points using Class A instrumentation.
Voltage THD and current TDD reported using the statistical basis the limit specifies.
Individual harmonic order assessment where the limit set includes per-order caps.
Compliance statement per point, with measurement uncertainty declared.
Non-compliance root cause where a point fails, and the shortest route to compliance.
Evidence pack in the format the utility or specifier requires.
What the work covers.
A focused compliance verification against a stated distortion limit — a utility connection condition, a lease clause, a specification or an internal standard. Narrower than a full harmonic study: the question is pass or fail against a defined limit at defined points.
Distortion limits are almost always statistical — a 95th-percentile of short-window values over a week, not an instantaneous reading. Reporting a peak instantaneous THD against a 95th-percentile limit will fail a site that actually complies.
What lands in your inbox.
Measurement at the defined compliance points using
Measurement at the defined compliance points using Class A instrumentation.
Voltage THD and current TDD reported using
Voltage THD and current TDD reported using the statistical basis the limit specifies.
Individual harmonic order assessment where the limit
Individual harmonic order assessment where the limit set includes per-order caps.
Compliance statement per point,
Compliance statement per point, with measurement uncertainty declared.
Non-compliance root cause where a point fails,
Non-compliance root cause where a point fails, and the shortest route to compliance.
Evidence pack in the format the utility
Evidence pack in the format the utility or specifier requires.
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: the exact limit document being tested against — connection agreement, lease or specification; agreed measurement points and the duration required; operating conditions that must be represented in the.
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 61000-4-30, IEC 61000-4-7, 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: utility has requested compliance evidence before or after connection; contractual handover requires a distortion compliance certificate; verification after mitigation has been installed. 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 the exact limit document being tested against — connection agreement, lease or specification; agreed measurement points and the duration required; operating conditions that must be represented in the measurement window. 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 61000-4-30, IEC 61000-4-7, EN 50160. 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.