UPS Harmonic Impact Assessment
Assessment of the harmonic behaviour of UPS installations on both input and output. Input distortion depends heavily on rectifier topology and on whether the UPS is running on mains, on battery or on bypass; output distortion matters for the critical load and is often overlooked entirely.
What this study establishes.
Input current spectrum by operating mode — normal, battery, bypass and recharge.
Assessment of recharge-phase distortion, which is typically the worst case and the shortest measured.
Output voltage distortion under linear and non-linear load, against IEC 62040-3 declarations.
Interaction assessment with generator supply, where source impedance is much higher than mains.
Input filter or rectifier upgrade options where distortion exceeds the allowance.
Transformer and neutral loading consequence upstream of the UPS.
What the work covers.
Assessment of the harmonic behaviour of UPS installations on both input and output. Input distortion depends heavily on rectifier topology and on whether the UPS is running on mains, on battery or on bypass; output distortion matters for the critical load and is often overlooked entirely.
The recharge phase is where UPS input distortion and demand peak simultaneously, and it coincides with the generator being the source. A study that measures only the steady normal-mode condition will miss the case that actually causes trouble.
What lands in your inbox.
Input current spectrum by operating mode
Input current spectrum by operating mode — normal, battery, bypass and recharge.
Assessment of recharge-phase distortion, which is typically
Assessment of recharge-phase distortion, which is typically the worst case and the shortest measured.
Output voltage distortion under linear and non-linear
Output voltage distortion under linear and non-linear load, against IEC 62040-3 declarations.
Interaction assessment
Interaction assessment with generator supply, where source impedance is much higher than mains.
Input filter or rectifier upgrade options where
Input filter or rectifier upgrade options where distortion exceeds the allowance.
Transformer and neutral loading consequence upstream of
Transformer and neutral loading consequence upstream of the UPS.
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: ups rating, rectifier topology and input filter arrangement; load profile and the proportion of non-linear critical load; generator data where the ups is backed by standby generation.
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 IEC 62040-3, IEEE 519-2022, IEC 61000-3-12, 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: generator struggles or trips when the ups recharges after a mains failure; distortion measured upstream of a ups exceeds expectation; adding ups capacity to an existing installation. 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 ups rating, rectifier topology and input filter arrangement; load profile and the proportion of non-linear critical load; generator data where the ups is backed by standby generation. Where any of it is missing we can establish it on site, which changes the scope rather than blocking the work.
Primarily IEC 62040-3, IEEE 519-2022, IEC 61000-3-12, IEC 61000-4-7. 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.