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Protection coordination

Compare upstream and downstream clearing times. A timing margin does not establish full selectivity.

Entered/static or sampled timing margins only. Passing does not establish full selective coordination or manufacturer discrimination.

min 0.0001 · max 100

min 0.0001 · max 100

min 0 · max 10

Select upstream device (library).

Select downstream device (library).

This tool needs an internet connection. Results are calculated on our servers.

Results

Enter inputs above, then tap Calculate.

Method and assumptions

Time grading plus optional I–t curve screening at stated fault currents (log-log interpolate). Not a full ELEK/ETAP coordination study.

Related calculators

Check the stated method and limits against your installation. Results are calculation aids, not certification.

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Calculation model 2026-11-02.1