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close this bookCircuits, Formulas and Tables Electrical Engineering - Basic vocational knowledge (Institut für Berufliche Entwicklung, 201 p.)
close this folder11. Basic symbols and formulas of electrical engineering
View the document(introduction...)
View the document11.1. General direct current engineering
View the document11.2. Magnetic field
View the document11.3. Law of induction
View the document11.4. Electric field
View the document11.5. Alternating current engineering
View the document11.6. 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