丹佛斯变频器FC51应用说明.pdf

Contents Contents Introduction 3 Normal Situation where the Three Phases are Balanced 3 One Phase Missing 4 Voltage on one Phase 3% Higher 4 Voltage on one Phase 3% Lower 5 Voltage on one Phase 3% Higher and 3% Lower on one of the Other Phases 5 One Diode Interrupted 6 Normal Situation but a very Stiff Main 6 1 1 Harmonic Measurements 1 2 1 Harmonic Measurements 1.1.1 Introduction The following pages describe current harmonics under different conditions. 1 The aim of this application note is to improve users background knowledge to evaluate harmonic measurements. All harmonics shown are for a 6-pulse rectifier (three phase supply). The conditions, which are covered in this application note, are: 1. Normal situation where the three phases are balanced. 2. One phase missing 3. Voltage on one phase 3% higher 4. Voltage on one phase 3% lower 5. Voltage on one phase 3% higher and 3% lower on one of the other phases 6. One diode interrupted 7. Normal situation but a very stiff main 1.1.2 Nor