Power Systems
Per-unit base, feeder voltage drop, transformer sizing, LV cable sizing and transformer-bus fault level — ported from PowerSys Pro + psextract.
◈System Base
Per-unit reference shared by fault calculations below.
〜Feeder Voltage Drop
3-phase feeder drop from R/X per km, length, load and PF.
▣Transformer Sizing + Fault Level
Recommended standard size, utilisation and symmetrical/asymmetrical fault current.
🔌LV Cable Sizing IEC 60364
Copper XLPE, derated for installation + ambient, with VD check.
⚠Short-Circuit at Bus
Fault current at transformer LV bus including feeder impedance.
📏Design Standards
Switches formulas, limits and references across the calculators.
📈Live Load Study 0–150%
Drag the slider — feeder VD, transformer loading and cable VD recalculate live from your inputs above. Same slider drives SLD loading colours.
Power Flow (Load Flow)
Newton–Raphson AC load flow on a user-editable network. Edit bus loads/generation and branch impedances, then solve — bus voltages, angles, branch flows and losses are computed, not mocked. Bus type: slack (1, reference), PV (generator, holds V), PQ (load).
Buses — edit V (kV), Type, P (kW), Q (kVar); Vm/angle are solved
| # | Name | V kV | Type | P kW | Q kVar | Vm p.u. | Va ° |
|---|
Branches — R, X in Ω, rating kVA
| From | To | R Ω | X Ω | Rate kVA | P→ kW | Q→ kVar | Load % | Loss kW |
|---|
Motor Starting — Voltage Dip
Locked-rotor inrush and the voltage dip it imposes at the point of common coupling (PCC). Impedance-divider method per IEC 60034-12 / AS-NZS 3000 §3.5. Checks against typical start-dip limits.
ⓂMotor + Supply
Motor nameplate + upstream fault level at the PCC.
📉Start Method Comparison
Same motor started four ways — effective inrush and resulting PCC dip.
| Method | I_start A | Dip % | Status |
|---|
Cable Short-Circuit Withstand
Adiabatic thermal check (IEC 60364-4-43 / BS 7671): a conductor must survive fault energy I²t without exceeding its insulation temperature. Computes minimum area and maximum permissible clearing time.
🔥Adiabatic Check k²S² ≥ I²t
k from material + insulation (BS 7671 Table 43.1).
📋k Factors
Typical conductor k (BS 7671 Table 43.1), for ≤5 s faults.
| Insulation | Cu | Al |
|---|---|---|
| XLPE / EPR (90°C) | 143 | 94 |
| PVC (70°C) | 115 | 76 |
| PVC (90°C) | 100 | 66 |
| Bare conductor | 176 | 116 |
Power Factor Correction
Size a capacitor bank to raise power factor to a target: Q_c = P·(tan φ₁ − tan φ₂). Includes detuning note for harmonic-rich systems.
⚙Capacitor Sizing
Existing load + present/target power factor.
📊What changes
Before vs after correction.
| Quantity | Before | After |
|---|
Arc Flash Hazard IEEE 1584-2018
Incident energy and arc-flash boundary per the IEEE 1584-2018 empirical model (1,800+ tests): arcing current (with reduced-current case), enclosure size correction, and PPE category per NFPA 70E. Safety-critical — verify against your protection study before use.
⚡Arc Flash Calculation
Equipment + fault data. Voltage 208 V–15 kV; G per equipment class.
🦺PPE Category NFPA 70E
PPE category from the highest (reduced-current) incident energy.
| Case | I_arc kA | E cal/cm² | AFB mm | PPE |
|---|
| PPE Cat | Incident energy |
|---|---|
| 0 / none | ≤ 1.2 cal/cm² |
| 1 | ≤ 4 |
| 2 | ≤ 8 |
| 3 | ≤ 25 |
| 4 | ≤ 40 |
Network Analysis Report
psextract-style system report. Edit bus voltages live — compliance re-evaluates instantly. Sample 5-bus demo case preloaded.
Bus Results — click Vm / load cells to edit
| Bus | Name | V (kV) | Vm (p.u.) | Va (°) | P (kW) | Q (kVar) | Status |
|---|
Branch Power Flows
| From | To | Pf (kW) | Qf (kVar) | Loading % | Status |
|---|
Short-Circuit Analysis (Z-bus method, sample)
| Bus | I_sc (kA) | S_sc (MVA) | Z_sc (Ω) | Breaker ≥ |
|---|
NERC Compliance
| Check | Result | Status |
|---|
Generator Dispatch
| Unit | P (kW) | Q (kVar) | Vset (p.u.) | Profile |
|---|
Single-Line Diagram Builder
Click a component on the left to drop it on the canvas — there are no modes to learn. The new symbol is placed for you and, if something is already selected, wired to it automatically, so you can build a feeder by simply clicking Generator → Breaker → Busbar → Transformer → Motor. To connect two things by hand, drag a ● dot onto another symbol — it snaps for you, so you don't need to aim precisely. The canvas is unlimited: pan with Space-drag or middle-drag and zoom out freely, and the grid follows you. Drag a symbol to move it (it snaps to the grid and shows alignment guides against its neighbours), click a breaker to open or close it, double-click a load to change its loading.
Components
Click to add · or drag onto the canvas
Start from a template
Start over
🗺 Draw your single-line diagram
Click a component on the left to drop it here — or start from a ready-made template.
Properties
Engineering Report
Collects your latest results from every module above into one professional report. Print or save as PDF.