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
• IEC 60364-5-52: 3% lighting, 5% other

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 / IEC 60909.

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