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Electrical Calculations

GorkyCAD performs all mandatory electrical calculations automatically as you design. Results update in real time — no manual recalculation needed.

Load Calculation

The Connected Load is calculated by summing the rated power of all consumers on a circuit. GorkyCAD applies demand factors according to the selected standard.

Per-circuit calculation:

  • Installed power: sum of all consumer ratings (kW)
  • Demand factor: configurable per circuit (0.5–1.0)
  • Design current: P / (√3 × U × cos φ) for three-phase

Per-phase balancing: GorkyCAD distributes single-phase loads across phases and shows the imbalance percentage. A warning appears if imbalance exceeds 15%.

Voltage Drop

Voltage drop is calculated for every circuit using the formula:

ΔU% = (ρ × L × I × 100) / (S × U)

Where:

  • ρ — conductor resistivity (copper: 0.0175 Ω·mm²/m, aluminum: 0.028 Ω·mm²/m)
  • L — one-way cable length (m)
  • I — design current (A)
  • S — conductor cross-section (mm²)
  • U — nominal voltage (230V phase, 400V line)

Limits per standard:

  • IEC 60364-5-52: 3% for lighting, 5% for other loads
  • IS 732 (India): 3% lighting, 5% power
  • ГОСТ Р 50571.5.52: 3% освещение, 5% прочие

If voltage drop exceeds the limit, GorkyCAD highlights the circuit in red and suggests a larger cross-section.

Short-Circuit Current

GorkyCAD calculates:

  • Ik” max — maximum short-circuit current at the busbar (for breaker breaking capacity)
  • Ik min — minimum short-circuit current at the end of the line (for tripping time verification)

Calculation follows IEC 60909 / ГОСТ 28249.

Required inputs:

  • Transformer power (kVA) and impedance voltage Uk%
  • Cable length, cross-section, and material
  • Busbar length and configuration (for 3D cabinets)

Protection Device Selectivity

For series-connected circuit breakers, GorkyCAD checks:

  • Overload selectivity — upstream breaker must not trip before downstream
  • Short-circuit selectivity — based on let-through energy I²t
  • Time-current curves — plotted for visual verification

The selectivity report shows PASS/FAIL for each pair with detailed reasoning.

Thermal Check

For distribution boards modeled in 3D:

  • Total heat dissipation of all devices (W)
  • Cabinet volume and ventilation type
  • Temperature rise °C

GorkyCAD warns if the internal temperature exceeds 40°C (IP54 enclosure) or 35°C (IP65).

Reports

All calculations are included in the Full Project PDF export:

  1. Load schedule — per-circuit and total
  2. Voltage drop table — every circuit
  3. Short-circuit currents — at busbar and endpoints
  4. Selectivity matrix
  5. Thermal report for 3D cabinets

Tips

  • Set the supply transformer parameters in Project Settings before starting
  • Verify demand factors — defaults are conservative
  • For industrial projects, enable motor starting current analysis
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