Sources of Harmonics:
Several sources of harmonic currents that may be found on electrical power distribution networks are listed below:
- Variable speed motor drives
- Rectifiers
- Arc furnaces
- Wielding equipment
- Uninterrupted power supplies
- Switching mode power supplies
- Compact fluorescent lamps
- Electronic ballasts
Disadvantages of Harmonics:
Harmonics degrades the performance of power system. Some of the disadvantages of harmonics in the power distributed network are listed below:
- The harmonics flowing in the distribution network downgrade the quality of the electrical power supply. There can have several negative effects on the operation of the power system
- Increased losses on the distribution system due to increase in the effective rms current
- Over-load in neutral conductors due to cumulative increase in the third harmonics created by the single phase loads
- Overloads, vibration and premature ageing of the generators, transformers and motors as well as increase in the noise level
- Overloads and premature ageing of the power factor correction capacitors
- Distortion of the supply voltage that can disturb the operation of the sensitive loads
- Disturbances in the communication networks and telephone lines
- Resonance between the supply inductance and capacitance of the power factor correction capacitors
