Study settings
Fault current is calculated from a radial multi-source sequence network with transformer voltage-base referral and per-device fault current. TCC coordination uses min/max curve bands; custom manufacturer curves can be pasted into each protective device. Optional KT uses the transparent IEC 60909-0:2016 equation set
0.95·cmax/(1+0.6·xT). For maximum 3φ faults, breaking-current screening uses the published 2016 μ/q equation set at 0.02/0.05/0.10/0.25 s. The displayed idc is deliberately labelled as a conservative source-branch R/X envelope, not a full meshed-network IEC Method-C result. For maximum faults, peak ip uses a Method-C network equivalent evaluated at 0.4f. For maximum 3φ faults, steady-state Ik can also be screened from explicit user/vendor generator IkP data; motors are excluded from 3φ steady state and UPS/converter steady current remains unresolved without vendor control data. The current IEC 60909-0 edition is 2026, so these equation-set features remain explicit pending equation-level delta verification. Legacy CCM / Parise is shown separately as a historical half-cycle branch-summation X/R diagnostic and is not IEC Method C.Case library
Select a standard case.
Current project is not linked to a library case.
Add downstream element
New element is attached to the selected item. Drag nodes on the SLD to reposition them.
Selected element
Device library
No library data loaded.
Manufacturer coordination pairs
No coordination-pair data loaded.
Selectivity and back-up/cascading are separate claims. Pair data are used only when exact assigned device-library references and system voltage match.
Interactive one-line diagram
Linked time-current characteristic (TCC)
Trip sequence at selected fault
Selected fault
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initial Ik″
—
peak ip · Method C
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breaking Ib
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idc envelope @ tb
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steady Ik screen
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legacy CCM equivalent X/R
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first trip
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clearing time
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path selectivity
Legacy CCM / Parise diagnostic
Available for maximum three-phase faults.
Historical comparison only. This branch-summation X/R method is distinct from IEC Method C; EasyPower removed Characteristic Current Method in its 2025 release.
Why did it trip?
Protection QA
Coordination pairs
Full fault study
Not run.
Export / project
Model self-test
Not run.
Standards register
- IEC 60909-0:2026 — current short-circuit standard. Breaking-current μ/q screening in this prototype is explicitly based on the published 2016 equation set pending equation-level 2026 delta verification.
- IEC 60255-151:2009 — over/under-current protection functions.
- IEEE C37.112-2018 — inverse-time relay equations.
- IEEE C37.110-2023 — CT application for relaying.
- IEC 61869-2:2012 — current transformers.
- IEC TR 61869-100:2017 — CT application in power-system protection.
- IEC 60947-2:2024 — circuit-breakers.
- IEC 60269-1:2024 — low-voltage fuses.
- IEC 60364-4-43:2023 — overcurrent protection.
- Characteristic Current Method (legacy) — half-cycle branch DC summation / equivalent X/R diagnostic; retained here only for comparison. EasyPower 2025 removed this method.