What is Harmonics?
Harmonics are multiples of the fundamental frequency of an electrical power system.
- For example, the fundamental frequency is 50 Hz, and then the 5th harmonic is five times that frequency, or 250 Hz.
- The substantial increase of electronic devices in an electrical distribution system causes Harmonics in Electrical System.
Harmonics are a growing concern in the management of electrical systems today. Designers are requested to pay more and more attention to energy savings and improved availability of electricity. But there is still a need for more explanation, in order to dissipate confusion and misinterpretation. Power electronic devices have become abundant nowadays due to their capabilities for precise process control and energy savings benefits. However, they also bring drawbacks to electrical distribution systems. The presence of harmonics in electrical systems means that current and voltage are distorted and deviate from sinusoidal waveforms.
Major Equipments that creates Harmonics
- Variable Frequency Drives (VFD) AC & DC Drives
- Variable Speed Drives (VSD)
- Soft Starters
- AC - DC Converter Equipments
- HVAC Systems
- Induction Furnace and Arc Furnace
- Welding machines
- CNC Machines
- Electronic equipment such as Computers, Printers, Scanners, etc
- Switching Equipments and Electronic circuits
- SMPS, Battery chargers
- UPS and Power Conditioning Equipments
- Large Nos. of CFL, Fluorescent lights with electronic ballast
- Thyristors, and many more non-linear equipments
Effects of Harmonics in Electrical Systems
- Indirect Higher Electricity Bills (Due to Poor Efficiency of Equipments)
- In-efficient performance of Electrical Equipments
- Premature Transformer Failures
- Neutral Conductor and Terminal Failures
- Circuit Breakers Tripp Frequently (MCB's, RCCB's, MCCB's, etc)
- Capacitor Bank Failures which leads to P.F penalty
- Malfunctioning of Motors or Failures
- Frequent Maintenance of Equipments
- Over Heating caused in Transformers , DG's, Cables, Bus Bars, Switches, Lugs, etc
- Conductor Failures
- Fuses Blowing
- Electronic Equipments Failures
- Flickering or Blinking of Lighting System
- Over Heating of Metal Parts of the Equipments, etc
- Losses in Distribution System
- Poor Power Quality in Distribution,
- Increases I^2 R Losses,
- Reduces life of equipments,
- Communication Equipments Failures, etc