Voltage sag and swell terms
How to record sag, swell, dip and interruption wording around Australian power-quality calculator records.
Term-record purpose
Sag, swell, dip and interruption words are easy to mix with other power-quality calculations. A voltage-unbalance value or THD value does not describe event duration by itself.
This guide keeps event language attached to the measurement record.
Workflow
- Identify whether the record is a steady measurement, start event or logged power-quality event.
- Record the term used by the analyser or report.
- Keep event duration and timestamp with the source record.
- Use voltage-unbalance or THD calculators only when their input type matches.
- Carry event records into DNSP, equipment or project review separately.
Term table
| Term | Record need | Do not confuse with |
|---|---|---|
| Sag or dip | Event magnitude and duration | Voltage unbalance percentage |
| Swell | Event over-voltage record | Nominal voltage setting |
| Interruption | Supply-loss event record | Harmonic distortion |
| Unbalance | Three comparable voltage readings | Sag duration |
| THD | Fundamental and harmonic RMS magnitudes | Voltage swell event |
Boundaries
- Do not calculate sag duration from spot voltages.
- Do not use THD as a voltage-event label.
- Do not remove analyser context from the term.
- Do not treat terminology as a network-performance decision.