Set and check protection: IDMT overcurrent and earth-fault relays to IEC 60255 and IEEE C37.112, grading across the full fault-current range, transformer differential slopes, breaker and fuse sizing, and the full protection coordination workbench with time-current curves.
Supporting tools cover generator synchronising checks, AFCI and GFCI requirements and surge protective device ratings.
The complete protection coordination workbench: time-current curves for IDMT, definite-time, LSIG breakers, MCB, fuses and motors, grading checks, damage curves, 87T/87B/87L, distance, 24/32/46/49/51V, 81/27/59, CT/VT sizing and LV board coordination.
IEC 60255 & IEEE C37.112 inverse-time curves. Add any number of relays to a chain and check full-range grading margin at every step.
Earth-fault IDMT trip time and optional instantaneous stage, reusing the verified IEC 60255-151 / IEEE C37.112 curve engine.
Percentage-bias dual-slope restraint characteristic trip/no-trip check, IEEE C37.91-consistent.
General continuous/non-continuous load OCPD sizing (NEC 210.19/215.2 + 240.4, or IEC 60364-4-43) and motor starting-current withstand sizing (NEC 430.52).
Voltage, frequency and phase-angle synchronization check (ANSI device 25 style) before closing a generator paralleling breaker.
Location-based lookup of NEC 210.12(A) AFCI and 210.8(A) GFCI dwelling-unit protection requirements, with citations.
SPD Type recommendation by location, minimum MCOV from system voltage/grounding, and SCCR check against available fault current.
How overcurrent, differential and arc-flash protection actually fit together — the core theory, the standards behind it, and a sensible order to work through this category's calculators.