Chart
ITIC-style voltage sag and swell tolerance envelope
Use an ITIC-style curve to understand voltage sag, swell, dropout, and equipment ride-through discussions.
Chart boundary
Does not diagnose a site event, prove equipment tolerance, set utility obligations, or replace power-quality monitoring.
itic envelope
Duration and voltage magnitude zones
A short deep sag and a long shallow sag can have different equipment effects; the two axes must be read together.
Scopepower qualityX-axisevent durationY-axisvoltage percent of nominalReviewAnnualNextVoltage imbalance percent calculator
Interruptiondeep low-voltage event
Can reset controls or electronics.
Sagbelow nominal
Duration and magnitude must be read together.
No-interruption bandreference envelope
Not proof of equipment tolerance.
Swellabove nominal
Overvoltage stress depends on duration.
Decision reference
Show how event duration and voltage magnitude combine to create power-quality risk zones for Canadian users reviewing sag and swell records.
| Curve band | What it shows | Risk cue | Handoff |
|---|---|---|---|
| Interruption zone | Very low voltage event | Dropout or reset | Power-quality monitor data |
| Sag zone | Reduced voltage for a duration | Motor contactor or drive trip | Equipment ride-through review |
| No-interruption band | Typically tolerated area | Equipment-specific exceptions | Manufacturer data |
| Swell zone | Elevated voltage event | Overvoltage stress | Utility/power-quality review |
Use notes
- Use this chart as a planning and conversation aid only.
- Confirm current utility requirements, product markings, manufacturer instructions, and local authority requirements before field work.
- Use the linked calculator or table when the task needs project-specific arithmetic.
Reference sources
Open the underlying public references before treating the chart as project guidance.