Non-linear load current
Drives, rectifiers, UPS systems and other converters can draw non-sinusoidal current whose spectrum changes with operating state and loading.
Engineering problem / industrial-harmonics
Industrial harmonics need a measurement boundary before a solution
Industrial harmonics need a measurement boundary and a system model: waveform distortion, loading, source impedance, operating states and the point of common coupling affect what the readings mean and what response is appropriate.
ObserveMeasureModelVerify
Observed signals
Symptoms frame the question. They do not prove the cause.
Record time, location and operating state before assigning a product or corrective action.
- 01
Power-quality measurements show current or voltage waveform distortion during particular equipment or production operating states.
- 02
Capacitors, transformers, conductors or protective devices experience unexpected stress that requires a wider system assessment rather than a component assumption.
- 03
Non-linear loads and correction equipment interact differently across operating combinations, making representative time-based measurement necessary.
Possible factors
Several conditions can produce a similar observation.
Network impedance
Source, transformer and feeder impedance influence voltage distortion and can create different readings at internal buses and the external point of evaluation.
Capacitor interaction
Capacitor banks and network inductance can shift impedance around harmonic frequencies, so correction equipment must be included in the system context.
Measurement interpretation
THD, TDD, individual orders, aggregation and the selected point of common coupling answer different questions and should not be interchanged.
Measurement set
Evidence needed before selection.
Define the measurement location and point of evaluation before interpreting voltage or current harmonic values.
Capture harmonic spectra, total distortion indicators, fundamental loading and relevant operating states with a documented measurement method.
Record the source, transformer, feeder, correction equipment and major non-linear loads needed to understand possible resonance or propagation paths.
Conceptual engineering diagramAIE / TECHNICAL PLATE
Connect the harmonic spectrum to its electrical boundary
The diagram organizes measurement and decision boundaries; it does not prescribe project ratings or settings.
Concept only
Final ratings, protection, earthing, settings and interlocks follow approved project engineering.
Open full-size SVGDecision sequence
Move from condition to verified action.
- 01
Define the question
State whether the concern is equipment stress, internal waveform quality, PCC evaluation, resonance risk or a proposed mitigation design.
- 02
Map the system
Mark the source, transformer, buses, feeders, non-linear loads, capacitor banks and intended measurement locations on the single-line diagram.
- 03
Measure operating states
Capture spectra, fundamental loading, voltage and current at comparable times and connect them to the equipment operating log.
- 04
Model and verify
Use the supported condition and system impedance context to select a response and define how its outcome will be checked at the agreed boundary.
Engineering boundary
A guide supports the next question, not a final design.
A harmonic spectrum alone does not select an active filter, detuned bank or SVG; system impedance and operating duty remain project inputs.
Compatibility limits, emission planning and equipment ratings must be established for the actual installation and applicable contractual boundary.
Direct answers
Common questions about the condition.
Is current THD enough to select a harmonic filter?
No. Individual orders, fundamental current, TDD context, measurement location, source impedance, load states and the accepted objective can all affect the selection.
Can a capacitor bank make harmonics worse?
Capacitance interacts with network inductance and can change impedance near harmonic frequencies, which is why resonance and harmonic context belong in the correction review.
Is an SVG the same as an active harmonic filter?
No. Both may use power electronics, but reactive-current control and harmonic-current compensation are distinct functions that must be specified and verified for the selected equipment.