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Circuit Breaker Wear & Maintenance Analyser

Estimate how much of a breaker's electrical endurance each pole has used from the currents it has interrupted, check operations against the mechanical endurance and follow the opening time — to plan maintenance by condition instead of by calendar.

Operations history

Breaker data

Result

Open an operations history or load the sample.

Tool guide · know before you use

What this tool is, how it works and how far to trust it

An analyser that estimates the electrical wear of each breaker pole from the interrupted currents and checks operations and opening time.

Read this before relying on a result. Every method, formula, assumption and limit is stated here, so you can check the answer yourself instead of accepting it blindly.

What it can do

  • Read an operations history CSV: date, type, interrupted current per phase or one value, and optionally opening time.
  • Build the electrical endurance curve through two manufacturer points and sum the wear per pole.
  • Give the remaining interruptions at 25, 50 and 100 % of the rated short-circuit current, compare operations with mechanical endurance, and flag opening times outside tolerance and their trend.

Why you need it

  • A breaker wears mainly when it interrupts current: a few high fault currents use more of the contacts than thousands of load operations.
  • Summing wear per pole tells which breakers need attention first, so maintenance follows condition rather than the calendar.

Understand this first

  • The endurance curve N(I) = Nr × (Ir / I)^n is a straight line on log-log axes between the rated current point and the short-circuit point.
  • Each interruption uses 1 / N(I) of the life of that pole; the sum is the wear (1.0 = endurance reached).
  • Opening time rising over the years usually points to the mechanism (lubrication, trip coil, latch), not the contacts.

What you need before you start

  • The breaker's operations history from the relay or breaker monitor (CSV), including interrupted currents.
  • The manufacturer's endurance points (operations at rated current and at rated short-circuit current), mechanical endurance and opening time with tolerance.
  • A current browser (Chrome, Edge, Firefox or Safari). Nothing is installed and your data is never uploaded; it is processed on your own computer.

How to use it

  • Open the history (or load the sample) and enter the breaker data.
  • Read the wear per pole, the assessment and the list of fault interruptions.
  • Repeat after each fault (or each year) with the updated history to follow the trend.

What you get

  • Wear per pole in %, the curve exponent, remaining interruptions, findings on mechanical endurance and opening time, and a table of fault interruptions.

How to read the results

  • Wear above about 70 % on a pole: plan contact inspection or replacement.
  • Opening time outside tolerance with low contact wear: inspect and service the mechanism.
  • Large differences between poles: single-phase faults concentrated on one phase — normal on lines, but confirm the CT and recording.

Technical basis

  • IEC 62271-100 electrical (E1/E2) and mechanical (M1/M2) endurance classes; manufacturer's endurance curve.

Limits: when not to rely on it

  • The two-point log-log line approximates the manufacturer's curve; use the curve itself where it is available.
  • Interrupted currents from the relay are RMS values at contact separation; arcing time and DC offset are not included.

Sample files for this tool

Download, open and compare with what the guide says you should see.

All sample files and what to expect →

For preliminary engineering use. Results must be checked by a qualified engineer against the project's standards. How results are checked · Terms & disclaimer · Privacy · Build 7cfcbe2 · 2026-11-14