From the Admiralty tables, he knew copper’s resistivity at 20°C: (or 0.0175 Ω·mm²/m). The manual demanded voltage drop not exceed 3% for power circuits.
What I can do is provide an based on the type of electrical calculation examples typically found in such Admiralty or naval engineering manuals. This will illustrate the principles, context, and practical application. Story: The Chief Electrician’s Logbook HM Destroyer Vigilant , North Atlantic, 1943 examples in electrical calculations by admiralty pdf
Required correction: (Q_c = Q_1 - Q_2 \approx 3.56\ \text{kVAR}) (capacitive). From the Admiralty tables, he knew copper’s resistivity
Gibbs calculated required capacitive reactive power to raise PF to 0.90. This will illustrate the principles, context, and practical
Load current: (I = P/V = 3000/110 \approx 27.3\ \text{A}). The fuse was rated 40 A — fine for overload. But for short-circuit, the prospective fault current matters.
Then cable cross-section area (A): [ A = \frac{\rho \times L}{R} = \frac{0.0175 \times 45}{0.0194} \approx 40.6\ \text{mm}^2 ]
Initial reactive power (Q_1 = \sqrt{S^2 - P^2} = \sqrt{8^2 - 5.2^2} \approx 6.08\ \text{kVAR})