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Fault Simulation Engine
IEC 60909 · IEC 60255 · IEEE 1584-2018
Network Configuration
TX Library
Feeder Cable
Cable Library
Leave R₂₀ blank to exclude cable impedance from study
Main MCCB Settings
Sub MCCB Settings
Arc Flash Parameters
Calculation Results
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Results for reference only — independently verify with a qualified engineer before use in any design or installation.
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Time-Current Characteristics (TCC)
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Device Registry
Device ID Type Role Rated (A) Breaking (kA) TMS ST Delay Health Status
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Calculation Audit Log
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Short-Circuit Analysis
IEC 60909:2016 · 3-Phase · L-L · Single-Phase-to-Earth
System
Network Elements (source → fault)
Add a Source element to begin
Add network elements and calculate
Arc Flash Hazard Analysis
IEEE 1584-2018 · NFPA 70E-2021 · PPE Category · Arc Flash Boundary
System & Fault Data
Equipment & Distance
Typical working distances: LV panel 455mm · MV switchgear 910mm · Open air 1800mm
Enter fault data and calculate
NEC Cable Sizing
NEC 2023 Art. 310.15 · AWG/kcmil · Temperature & Conduit Fill Correction · Voltage Drop
Circuit Parameters
Conductor
Limits & Optional SC Check
Enter circuit parameters and click Size Conductor.
Harmonic Analysis
IEEE 519-2022 / IEC 61000-3-12 · THD_I · TDD · THD_V · Per-Harmonic Limits
System Data (PCC)
Harmonic Sources
Add harmonic sources and click Analyse Harmonics.
Power Quality Assessment
IEC 61000 / EN 50160 · Voltage Sag/Swell · Flicker (Pst) · ITIC / SEMI F47 Compliance
System
Voltage Sag Event
Flicker
Enter system data and click Assess Power Quality.
Relay Coordination
IEC 60255-151 / IEEE C37.112 · IDMT & DTL · Auto-grading · TCC Curves
System
Relays (downstream → upstream)
Add relays and click Coordinate Relays.
Distance Protection
IEC 60255-13 · Zone 1/2/3 Reach · MHO / Quadrilateral · Load Blinder · SIR Check
Line & System
Adjacent Line (for Zone 3)
Zone Settings
Load Blinder & Source (optional)
Enter line parameters and click Calculate Zones.
Transformer Differential Protection
IEC 60255-111 · Biased Differential · Inrush Restraint · Slope Settings · Trip Decision
Transformer Data
Operating Currents (pu)
Relay Settings
Enter transformer and relay data, then click Analyse Differential.
Motor Starting Analysis
IEC 60034 / NEMA MG-1 · DOL · Star-Delta · Soft-Starter · VFD · Voltage Dip
Motor Nameplate
Starting Method & System
Enter motor data and click Analyse Motor Starting.
Soft Starter Sizing
IEC 60947-4-2 · IEC 60034-12 · Frame Selection · Thermal Model · Voltage Sag
Motor Nameplate
Load & Starter Settings
Options
Supply (optional — for voltage sag)
Enter motor data and click Size Soft Starter.
VFD Sizing
IEC 61800-2 · Drive Frame Selection · Harmonic Analysis · Braking Resistor · IEEE 519 TDD
Motor Nameplate
Drive & System Settings
Enter motor data and click Size VFD.
Generator Sizing
IEC 60034 / ISO 8528 · kVA Rating · Step-Load Voltage Dip · Fuel Consumption
Generator Parameters
Load Schedule
Description kW PF DF Lgst M
Add loads and click Size Generator.
Overhead Line Rating
IEEE 738-2023 · Static Thermal Rating · ACSR Conductor · Sag Estimate
Conductor
Environmental Conditions
Select conductor and conditions, then click Calculate Rating.
Power Factor Correction
IEC 60831-1 · Capacitor Bank Sizing · Detuning Reactor · Economic Payback
Load & System
Capacitor Bank Options
Economics
Enter load data and click Calculate PF Correction.
Transformer Sizing
IEC 60076-1 / IS 2026 · Load Schedule · Voltage Regulation · Efficiency · Inrush
System
Load Schedule
Add loads and click Size Transformer.
Load Estimation
IEC 60364-3 / NEC 220 · Demand Factors · Diversity · Feeder & Transformer Sizing
System Parameters
Load Schedule
Description kW PF Qty Category DF ovrd
Add loads and click Estimate Load.
Earthing / Ground Grid Design
IEEE 80-2013 · Mesh & Step Voltage · Grid Resistance · Conductor Sizing · GPR
Grid Geometry
Soil & Surface
Fault & Conductor
Enter grid parameters and click Design Earth Grid.
Solar PV Sizing
IEC 62446 / IEC 61730 · String Config · Inverter Match · Voltage Check · Annual Yield
Module Data (STC)
Array Configuration
Inverter & Site
Enter module and site data, then click Size Solar PV.
BESS Sizing
IEC 62933 / UL 9540 · Energy Capacity · C-Rate · DoD · Cycle Life · PCS Rating
Load & Application
Battery Chemistry & Settings
Enter load and battery parameters, then click Size BESS.
Single Line Diagram Editor
IEC 60617 · Drag & Drop · Orthogonal Wiring · SVG Export
Scroll to zoom · Drag to pan · Delete key removes selected Full Editor ↗
Scroll = zoom · Drag canvas = pan
Click an element
to inspect it
Busbar Sizing Calculator
IEC 60865-1:2011 · Thermal Withstand · Current Capacity · EM Force
Load & System
Short-Circuit Parameters
Busbar Configuration
Electromagnetic Force (optional)
Provide phase spacing to compute peak EM force per metre (IEC 60865-1 Cl. 7).
Configure load and fault data, then click Size Busbar
Cable Sizing Calculator
IEC 60364-5-52:2009 · Thermal · Voltage Drop · SC Withstand
Load Details
Installation Conditions
Cable Specification
Voltage Drop
Short-Circuit Withstand (optional)
If provided, adiabatic equation A ≥ I·√t / k (IEC 60364-4-43) is checked.
Configure load and installation, then click Size Cable
Load Flow Analysis
Newton-Raphson · Balanced 3-Phase · IEEE Std 399 / IEC 60909
Study Settings
Buses
#NameType V nom (kV)V init (pu) P (MW)Q (MVAR)
Branches
From Bus #To Bus # R (pu)X (pu) B (pu)Rating (MVA)
R, X, B in per-unit on system base MVA. Bus # is 0-indexed (matches row order above).
Configure buses and branches, then Run Load Flow
Equipment Library
IEC 60228 · IEC 60076 · Org Custom Items
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Cable Type Size (mm²) R₂₀ (Ω/km) R₉₀ (Ω/km) X (Ω/km) Imax (A) Source
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Knowledge Base — Engineering Reference
Standards · Formulas · Guides
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Calculation Methodology
Standards · Clauses · Assumptions · Limitations
This page documents the exact standard, clause, voltage factor, method, and assumptions applied for each GridSense calculation module. It is intended to be used as a reference when reviewing results with a qualified engineer.
⚠ All results must be independently verified before use in any design, installation, or construction document.
IEC 60909 Short-Circuit Analysis
StandardIEC 60909-0:2016
Applicable ClauseSection 4 — Calculation of short-circuit currents
Voltage Factor cTable 1 — cmax = 1.1 (LV ≤1 kV), cmax = 1.1 (MV 1–35 kV), cmax = 1.1 (HV >35 kV)
MethodEquivalent voltage source at fault location (complete method, not simplified)
Fault TypesThree-phase (I"k3), Line-to-line (I"k2), Line-to-earth (I"k1), Line-to-line-to-earth (I"k2E)
Motor ContributionIncluded per Section 4.3.4 (IEC 60909-0:2016) — motors >1 kW contribute to initial symmetrical short-circuit current I"k
Impedance Correction FactorsKT for transformers (Eq. 12), KG for generators (Eq. 15), ZQ for network feeders from Eq. 1
Peak Currentip = κ × √2 × I"k — κ from Table 3 (characteristic frequency ratio R/X)
Assumptions & LimitationsBalanced three-phase supply assumed. Shunt admittances (capacitances, non-rotating loads) neglected per Cl. 5.1. Pre-fault voltage = rated voltage × cmax. Results represent worst-case maximum initial short-circuit current — not steady-state. Network is modelled as a single equivalent source unless multi-infeed topology is explicitly defined.
IEEE 1584 Arc Flash Hazard Analysis
StandardIEEE 1584-2018 (2nd edition)
Applicable ClauseSection 4 — Empirical model, arc flash boundary & incident energy
Model TypeEmpirical (laboratory-derived regression model) — replaces simplified 2002 model
Voltage Range208 V – 15,000 V (LV and MV systems)
Enclosure TypesOpen air, VCB (vertical conductors in a box), HCB (horizontal conductors in a box), VOA, HOA
PPE CategoriesNFPA 70E Table 130.5(G) — Cal/cm² thresholds: Cat 1 = 1.2, Cat 2 = 12, Cat 3 = 40, Cat 4 = 100 cal/cm²
Incident EnergyE = 12.552/D² × t × 10^(K1 + K2 + 0.0011×G) — normalised to 610 mm working distance, then scaled
Arcing CurrentCalculated per IEEE 1584-2018 Eq. C.1–C.3; both maximum and minimum arcing currents evaluated
Assumptions & LimitationsAssumes bolted fault current from IEC 60909 calculation. Arc duration = upstream protective device clearing time. Model validated for 208 V–15 kV; extrapolation outside this range is not recommended. Thermal incident energy only — blast pressure and shrapnel hazards are outside model scope. Working distance must be specified correctly for the equipment type per NFPA 70E Table 130.5(C).
IEC 60255 Relay Coordination (TCC Curves)
StandardIEC 60255-151:2009 (overcurrent relay measurement functions)
Curve FamiliesStandard Inverse (SI), Very Inverse (VI), Extremely Inverse (EI), Long-Time Inverse (LTI), Definite Time (DT)
Operating Formulat = TMS × [α / ((I/Is)^β − 1) + L] — IEC 60255-151 Table 1 coefficients
Curve Coefficients SI: α=0.14, β=0.02, L=0 | VI: α=13.5, β=1, L=0 | EI: α=80, β=2, L=0 | LTI: α=120, β=1, L=0
Coordination MarginMinimum grading margin Δt ≥ 0.25 s (electromechanical), ≥ 0.20 s (numerical) — per IEC 60255 guidance
Also SupportedIEEE C37.112-1996 curves (US style): Moderately Inverse, Inverse, Very Inverse, Extremely Inverse, Short-Time Inverse
Assumptions & LimitationsFault current at each bus is sourced from the IEC 60909 short-circuit module. CT saturation, relay reset time, and breaker interrupt time are not modelled. TCC curves are plotted assuming relay operates at rated frequency. Actual relay settings must be confirmed against manufacturer datasheets before programming.
Newton-Raphson Load Flow Analysis
MethodNewton-Raphson iterative power flow — industry standard for meshed networks
Convergence Criterion|ΔP|, |ΔQ| < 10−6 pu per iteration
Bus TypesSlack (swing) bus — V & δ fixed; PV bus — P & |V| specified; PQ bus — P & Q specified
Per-Unit System100 MVA base. Voltage base = rated kV at each bus. All branch impedances converted to pu before solution.
OutputsBus voltages (pu & kV), branch power flows (MW, Mvar), line losses, voltage deviations from nominal
Voltage LimitsFlagged per IEC 60038 — ±10% for LV, ±5% for MV/HV steady-state tolerance
Assumptions & LimitationsAssumes balanced three-phase steady-state conditions. Transformer tap positions assumed at nominal unless specified. Shunt capacitors and reactors modelled as fixed susceptances. Dynamic stability and transient effects are out of scope.
IEC 60364 Cable Sizing (IEC)
StandardIEC 60364-5-52:2009 — Wiring systems selection & erection
Current Capacity MethodTable B.52.2–B.52.21 — tabulated current-carrying capacity Iz for each installation method
Derating FactorsCa — ambient temperature (Table B.52.14); Cg — grouping (Table B.52.17); Ci — thermal insulation
Voltage DropΔU = √3 × I × L × (R cosφ + X sinφ) — IEC 60364-5-52 Annex G. Limit: 3% LV final circuit, 5% total
Short-Circuit Rating CheckS ≥ Ik × √t / k — adiabatic equation per IEC 60364-5-54 Cl. 543.1 (k from Table 43A)
Conductor MaterialCopper (k=143) and Aluminium (k=95) — IEC 60364 Table 43A values used for adiabatic check
Assumptions & LimitationsTabulated values assume XLPE or PVC insulation as selected. Direct buried cables use soil thermal resistivity ρ = 1.0 K·m/W unless specified. Cable armour contribution to earth fault current not included. Harmonic loading derating (IEC 60364-5-52 Annex F) applied only when harmonic analysis module is run in the same study.
IEC 60865 Busbar Sizing
StandardIEC 60865-1:2011 — Short-circuit currents, calculation of effects
Thermal RatingContinuous current rating from cross-sectional area & surface cooling — Neher-McGrath method adapted for busbars
Short-Circuit WithstandAdiabatic temperature rise check: S ≥ Ik × √t / k — same as cable (IEC 60865-1 Cl. 4)
Electromagnetic ForcePeak force between parallel busbars: F/L = μ₀/(2π) × ip² / a — IEC 60865-1 Eq. 2 (a = centreline spacing)
Skin EffectAC resistance correction applied for conductors >50 mm² using skin-effect factor from IEC 60287-1-1
Materials SupportedElectrolytic copper (E-Cu), Aluminium alloy (Al 99.5), Aluminium-copper composite
Assumptions & LimitationsAssumes rectangular section busbars mounted on edge. Enclosure derating not automatically applied — if in enclosed switchboard, apply additional derating factor manually. Vibration resonance effects and dynamic mechanical stress on supports are outside model scope and must be checked by mechanical design.
IEC 60076 Transformer Sizing
StandardIEC 60076-1:2011 — Power transformers, general requirements
Sizing BasiskVA demand = (connected load × demand factor) / power factor. Rating selected from IEC 60076 preferred kVA series.
Impedance Referenceuk % from IEC 60076-1 Table 9 preferred values (e.g. 4% for ≤630 kVA, 6% for 630–2500 kVA)
LossesNo-load loss (P0) and load loss (Pk) from IEC 60076-1 Table 1 — efficiency & annual cost computed
Inrush CurrentEstimated at 8–12× In (peak) for 0.1 s — used as reference for upstream relay setting, per IEC 60076-1 Cl. 8
Temperature RiseONAN (Oil Natural Air Natural): ΔTtop oil ≤ 60 K, winding hotspot ≤ 78 K above ambient — per IEC 60076-2
Assumptions & LimitationsDemand factor must be user-specified — GridSense does not auto-calculate diversity unless load schedule is entered in the project. Actual impedance of a specific transformer must be taken from its test certificate. Inrush current multiplier is an engineering estimate — actual value varies significantly by core material and switching angle.
IEEE 80 Earthing Grid Design
StandardIEEE Std 80-2013 — Guide for safety in AC substation grounding
Tolerable VoltagesTouch voltage Etouch = (1000 + 6Csρs) × 0.116/√tf — IEEE 80 Eq. 32 (for 50 kg body weight, 70 kg available)
Mesh & Step VoltageEm = ρ × IG × Km × Ki / Lc and Es = ρ × IG × Ks × Ki / Ls — IEEE 80 Eq. 80 & 92
Ground ResistanceRg = ρ × [1/LT + (1/√(20A)) × (1 + 1/(1+h√(20/A)))] — Schwarz/Laurent-Niemann simplified formula
Surface LayerCrushed rock derating factor Cs from IEEE 80 Figure 11 (function of ρs/ρ and depth hs)
Fault Current SplitDecrement factor Df from IEEE 80 Table 13 — accounts for DC offset during fault clearing
Assumptions & LimitationsAssumes uniform soil resistivity — two-layer soil models are not currently implemented (use Wenner 4-pin test data for site-specific ρ). Fault current split factor between grid and overhead ground wires is set to 1.0 (conservative — 100% through grid) unless user specifies cable/OHL configuration. Grid must be entered as rectangular mesh; irregular shapes are approximated.
IEC 60034 Motor Starting Analysis
StandardIEC 60034-1:2010 — Rotating electrical machines, rating & performance
Starting CurrentIstart = In × LRC — Locked Rotor Current ratio (typically 5–8× In per IEC 60034-12)
Voltage Drop at StartΔV = Zsource × Istart / Vn — check bus voltage remains >80% Vn during start (IEC 60038)
Starter Types ModelledDOL, Star-Delta (Istart ÷ 3), Autotransformer (tap 65%/80%), Soft Starter, VFD (near zero inrush)
Thermal CheckMotor thermal withstand: I²t during start vs. thermal limit curve from IEC 60034-1 Cl. 8.2.5
Source ImpedanceZsource at motor terminals from IEC 60909 short-circuit module (Thevenin equivalent)
Assumptions & LimitationsAssumes squirrel-cage induction motor (SCIM). Wound-rotor and synchronous motor starting are not modelled. Speed-torque curve is not simulated — only peak starting current and voltage dip are evaluated. Multiple simultaneous motor starts can be manually superimposed by running separate cases.
IEC 61000 Harmonic Analysis
StandardIEC 61000-3-6:2008 — Harmonic emission assessment (MV, HV, EHV)
THD Limit (Voltage)THDV ≤ 8% LV (IEC 61000-2-2), ≤ 5% MV (IEC 61000-3-6 Table 1)
Harmonic Orders3rd, 5th, 7th, 11th, 13th, 23rd, 25th — characteristic harmonics from 6-pulse and 12-pulse drives
Frequency ScanImpedance vs. frequency plotted from fundamental to 50th harmonic — identifies resonance peaks (X/R = minimum)
Cable DeratingTHD-adjusted derating per IEC 60364-5-52 Annex F — neutral conductor oversized when THD > 15%
Filter DesignPassive single-tuned filter: C tuned to hn = 1/(2π√(LC)) — quality factor Q recommended 30–60
Assumptions & LimitationsHarmonic sources are entered as ideal current injections (Norton model). Background distortion from the utility is not automatically imported — enter as separate harmonic voltage source if known. Interharmonics and sub-harmonics are not modelled. Results are steady-state — transient harmonic events during motor starting require dedicated power quality monitoring.
IEC 60831 Power Factor Correction
StandardIEC 60831-1:2014 — Shunt power capacitors for AC systems up to 1 kV
Required CapacitanceQc = P × (tan φ1 − tan φ2) kvar — where φ1 = existing PF angle, φ2 = target PF angle
Anti-Resonance CheckResonant harmonic order hr = √(Ssc/Qc) — check hr does not coincide with characteristic harmonic (5, 7, 11, 13)
Detuning Reactorp = 5.67% or 7% reactor tuned to h = 4.3 or 3.78 — per IEC 60831 to avoid 5th harmonic resonance
Capacitor RatingIEC 60831 preferred kvar series: 12.5, 25, 37.5, 50, 75, 100, 150, 200, 300, 400, 500 kvar per unit
Overcurrent at PCCCapacitor bank inrush current Ipeak estimated — check against upstream OCR setting (relay shall not trip on energisation)
Assumptions & LimitationsFixed capacitor bank assumed (not APFC/automatic). Harmonic content at the bus must be checked separately using the Harmonic Analysis module before finalising capacitor sizing — unchecked resonance can cause capacitor failure and amplify voltage distortion. Temperature derating of capacitor kvar rating (IEC 60831-1 Cl. 5.2) not applied unless ambient temperature >40°C is specified.
Engineering Disclaimer: This methodology documentation describes the theoretical basis of GridSense calculations. All results generated by this software are for engineering reference only and must be independently verified by a qualified professional engineer (PE/CEng) before use in any design, installation, commissioning, or construction document. GridSense and JDSAN Controls accept no liability for decisions made solely on the basis of software output.
Calculator Hub
22 calculation engines · 7 functional groups · IEC / IEEE / NEC
Status: Full UI — wizard available in top tabs API Ready — backend live, wizard coming soon
GROUP A Fault Analysis 3 engines
Short Circuit Full UI
IEC 60909-0:2016
3-phase, L-L, L-E, L-L-E fault currents · peak / breaking
Arc Flash Full UI
IEEE 1584-2018
Incident energy · PPE category · arc flash boundary
Harmonic Analysis Full UI
IEC 61000-3-6 / IEEE 519
THD · individual harmonic limits · filter sizing
GROUP B Protection Engineering 4 engines
Relay Coordination Full UI
IEC 60255-151
IDMT curves · TCC coordination · grading margin
Motor Starting Full UI
IEC 60034-12
Voltage dip · starting time · protection grading
Distance Protection Full UI
IEC 60255-13
Zone 1/2/3 impedance reach · MHO / quadrilateral
Transformer Differential Full UI
IEC 60255-111
Biased differential · inrush restraint · slope settings
GROUP C Motor & Drive Systems 3 engines
VFD Sizing Full UI
IEC 61800-2
Drive frame sizing · overload · input filter · braking
Soft Starter Sizing Full UI
IEC 60947-4-2
Frame sizing · ramp settings · starts/hr · thyristor loss
Generator Sizing Full UI
IEC 60034 / ISO 8528
kVA rating · derating · fuel consumption · paralleling
GROUP D Cable, Busbar & Earthing 4 engines
Cable Sizing (IEC) Full UI
IEC 60364-5-52
Current capacity · volt drop · derating factors · CCC
Cable Sizing (NEC) Full UI
NEC 310 / NFPA 70
AWG / kcmil · ampacity · conduit fill · voltage drop
Busbar Sizing Full UI
IEC 60865-1
Thermal · mechanical · short-circuit withstand · eddy loss
Earthing Grid Full UI
IEEE 80-2013
Touch & step voltage · grid resistance · conductor sizing
GROUP E Power System Analysis 4 engines
Load Flow Full UI
Newton-Raphson / IEC
Bus voltages · branch flows · losses · power balance
Power Factor Correction Full UI
IEC 60831 / 61921
kVAr bank sizing · capacitor selection · harmonic risk
Transformer Sizing Full UI
IEC 60076
kVA rating · impedance · losses · vector group
Load Estimation Full UI
IEC 60364-3 / NEC 220
Demand factors · diversity · transformer recommendation
GROUP F Renewable Energy & Storage 3 engines
Solar PV Sizing Full UI
IEC 62446 / IEC 61730
Array sizing · string config · inverter matching · yield
BESS Sizing Full UI
IEC 62933 / UL 9540
Energy capacity · C-rate · DoD · cycle life · BMS settings
Power Quality Full UI
IEC 61000 / EN 50160
Voltage sag/swell · flicker · ITIC/SEMI F47 compliance
GROUP G Overhead Lines 1 engine
Overhead Line Rating Full UI
IEEE 738-2023
Static & dynamic thermal rating · ACSR conductor types

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