Motor Insulation Resistance (IR) Trend Tracker
Log insulation resistance readings, see the wear trend and get a projected date when the 5 MΩ limit will be reached.
Readings stay in your browser (localStorage) — nothing is uploaded.
Straight-line (least-squares) extrapolation of your logged readings to the 5 MΩ alarm threshold (warning at 20 MΩ). A low R² means the trend is noisy — log more readings before trusting the projection.
Field notes from maintenance practice
Temperature correction is the whole game: IR roughly halves per 10 °C rise, so an uncorrected winter reading vs a summer reading fabricates a trend. IEEE 43's rule — double the measured IR for every 10 °C the winding is above 40 °C (halve below) — must be applied before you log here. The polarization index (10-min/1-min ratio) is the companion check; a PI under 2 with falling IR means moisture. The default action limit of 5 MΩ comes from IEEE 43, whose minimum for most random-wound motors is IR₁min = 5 MΩ (corrected to 40 °C); the warning level gives you a season of lead time; adjust it if your OEM or procedure specifies otherwise.
Linear extrapolation is honest only when the R² is decent (≥ 0.7) and degradation is steady. IR drifts down slowly with contamination and moisture, then collapses quickly once cracking or tracking starts — and it swings hugely with temperature, so always correct to 40 °C before logging. If the last reading jumps far off the line, re-measure before believing it — measurement technique drifts too.
Sources & references
- IEEE 43 — recommended practice for testing insulation resistance of electric machinery
- IEEE 95 — high direct-voltage testing guidance
Trend screening only — confirm with a proper inspection before running equipment to a projected limit.
Motor Insulation Resistance (IR) Trend Tracker for maintenance and reliability teams: Log insulation resistance readings, see the wear trend and get a projected date when the 5 MΩ limit will be reached. Free, private (everything runs in your browser) and ready for daily plant use.
About Motor Insulation Resistance (IR) Trend Tracker
This tracker is a remaining-useful-life (RUL) estimator for insulation resistance. Log a dated reading whenever you measure; the tool fits a least-squares straight line through your history and projects when it will cross the 5 MΩ action limit (warning at 20 MΩ) — turning scattered measurements into a forecast date you can plan parts and downtime around.
How to use Motor Insulation Resistance (IR) Trend Tracker
- 1Enter each dated measurement as you take it — readings persist in your browser between visits.
- 2Adjust the alarm (and warning) threshold to your OEM or procedure limit if it differs from the default.
- 3Read the fitted trend, R², days-to-alarm and the projected date — then plan parts and downtime around that date.
Why use Motor Insulation Resistance (IR) Trend Tracker?
- ✓Log insulation resistance readings, see the wear trend and get a projected date when the 5 MΩ limit will be reached — computed instantly with the standard formula
- ✓100% free and unlimited, with no sign-up, login or paywall
- ✓Runs entirely in your browser — readings and asset data never leave your device
- ✓Niche-specific defaults and thresholds for insulation resistance, traceable to the cited standards
Frequently asked questions
What limit should trigger action for insulation resistance?+
The widely used limit is 5 MΩ (IEEE 43, whose minimum for most random-wound motors is IR₁min = 5 MΩ (corrected to 40 °C); the warning level gives you a season of lead time). Set a warning at 20 MΩ so parts and labour are ready before the alarm. Your OEM manual or internal procedure overrides the generic figure.
My megger reading dropped 80% after the motor sat through monsoon — rewind time?+
Dry it first. Moisture absorption collapses IR reversibly: bake the winding (space heaters, gentle external heat or controlled current) to 60–70 °C for 12–24 h and re-test. If IR recovers above the minimum and PI ≥ 2, return it to service with heaters left energised during idle periods. Rewind only if IR stays low after a proper dry-out — that points to cracked, contaminated insulation.
How many readings before the projection is trustworthy?+
At least 4–6 spread over a meaningful fraction of the asset's life, with a fit R² of about 0.7 or better. Two points always make a perfect line — that is curve fitting, not condition monitoring. Keep measurement conditions (load, temperature, location) consistent.
Is straight-line extrapolation valid for wear?+
It is the standard first approximation for steady-state degradation, and it is deliberately conservative to act on. Many failure modes accelerate near the end (bathtub curve), so treat the projected date as the latest acceptable intervention date, not a promise.
Where is my logged data stored?+
Entirely in your browser's localStorage on this device — nothing is uploaded to any server. Export or note critical values elsewhere if you need a permanent maintenance record shared across a team.
Embed Motor Insulation Resistance (IR) Trend Tracker on your website
Want Motor Insulation Resistance (IR) Trend Trackeron your own site? Paste this snippet into any HTML page — it's free, with no API key or sign-up. The tool loads in an iframe and keeps working exactly as it does here.
<iframe src="https://tooljolt.com/tools/insulation-resistance-trend-tracker" width="100%" height="640" style="border:1px solid #e5e7eb;border-radius:12px;max-width:680px" title="Motor Insulation Resistance (IR) Trend Tracker — ToolJolt" loading="lazy"></iframe>Related Industrial tools
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