Circuits, Formulas and Tables Electrical Engineering - Basic vocational knowledge (Institut für Berufliche Entwicklung, 201 p.)
 11. Basic symbols and formulas of electrical engineering
 (introduction...) 11.1. General direct current engineering 11.2. Magnetic field 11.3. Law of induction 11.4. Electric field 11.5. Alternating current engineering 11.6. Calculation of power

### 11.6. Calculation of power

calculation of power losses

PV = power loss in per cent

direct current

 [%]

single-phase alternating current

 [%]

three-phase alternating current

 [%] [V]; [V] [V]; [V] [V]; [V]

Determination of a conductor cross-section

- Calculation of the rated current from current, voltage and power factor.

- Division by all suitable current-carrying capacity factors of the Tables 9 to 12.

- Determination of the conductor cross-section according to the given current-carrying capacity factors after the calculated fictive current.

- Calculation of the conductor cross-sections according to the given power and voltage loss.

- Comparison of the cross-sections found out under the third and fourth point. The greatest is chosen as the cross-section to be installed.

Conversion of the measuring units of work and power

Work

 J erg kpm kWh PSh kcal 1 1 107 0.102 0.278 · 10-6 0.378 · 10-6 0.239 · 10-3 107 1 0.102 · 10-7 0.278 · 10-13 0.378 · 10-13 0.239 · 10-10 9.81 9.81 · 107 1 2.72 · 10-6 3.70 · 10-6 2.34 · 10-3 3.60 · 106 3.60 · 1013 3.67 · 105 1 1.36 860 2.65 · 106 2.65 · 1013 2.70 · 105 0.7355 1 632 4187 4.19 · 1010 427 1.16 · 10-3 1.58 · 10-3 1

Power

 W kW kpm s-1 PS kcal s-1 kcal h-1 1 10-3 0.102 1.36 · 10-3 2.39 · 10-4 0.86 103 1 102 1.36 0.239 860 9.81 9.81 · 10-3 1 0.0133 2.34 · 10-3 8.43 735.5 0.7355 75 1 0.1757 632 4187 4.19 427 5.69 1 3600 1.16 1.16 · 10-3 0.119 1.58 · 10-3 2.78 · 10-4 1