Chapter A General rules of electrical installation design

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Chapter L
Power factor correction and
harmonic filtering
Contents
Reactive energy and power factor L2
1.1 The nature of reactive energy L2
1.2 Equipment and appliances requiring reactive energy L2
1.3 The power factor L3
1.4 Practical values of power factor L4
Why to improve the power factor? L5
2.1 Reduction in the cost of electricity L5
2.2 Technical/economic optimization L5
How to improve the power factor? L7
3.1 Theoretical principles L7
3.2 By using what equipment? L7
3.3 The choice between a fixed or automatically-regulated bank L9
of capacitors
Where to install power factor correction capacitors? L 0
4.1 Global compensation L10
4.2 Compensation by sector L10
4.3 Individual compensation L11
How to decide the optimum level of compensation? L 2
5.1 General method L12
5.2 Simplified method L12
5.3 Method based on the avoidance of tariff penalties L14
5.4 Method based on reduction of declared maximum apparent
power (kVA) L14
Compensation at the terminals of a transformer L 5
6.1 Compensation to increase the available active power output L15
6.2 Compensation of reactive energy absorbed by the transformer L16
Power factor correction of induction motors L 8
7.1 Connection of a capacitor bank and protection settings L18
7.2 How self-excitation of an induction motor can be avoided L19
Example of an installation before and L20
after power-factor correction
The effects of harmonics L2
9.1 Problems arising from power-system harmonics L21
9.2 Possible solutions L21
9.3 Choosing the optimum solution L23
Implementation of capacitor banks L24
10.1 Capacitor elements L24
10.2 Choice of protection, control devices and connecting cables L25
Schneider Electric - Electrical installation guide 2008
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