Harmonics in Power Systems:
What are the sources of harmonics?
- Electronic equipment such as personal computers
- Battery chargers
- Lighting dimmer controls
- Fluorescent lights
- Electronic ballasts
- Printers
- Photocopiers
- Fax machines
- SCR or thyristor devices used in various applications for the control or regulation of drives
- Frequency conversion (variable-speed drives)
- Arc furnaces and arc welding equipment
- In transformers, Harmonics cause Iron Losses and Overheating.
- Capacitor Banks deteriorate and reduces life expectancy.
- Voltage distortions
- Excessive currents on neutral wires
- Overheating of motors
- Microprocessor control problems
- Unexplained computer crashes There may be interference with communication and auto tone control equipment.
- Metering may not register properly.
- Harmonic currents circulating in the power system increase copper losses and the heating of equipment, such as transformers and generators.
- Generators can have additional problems with excessive harmonic voltage distortion, causing multiple zero crossings of the current waveform. This can cause interference and operation instability.
- Breaker and fuse operations may occur for no apparent reason
Benefits of Harmonic Filtering:
- Reduces neutral currents
- Reduces transformer loading
- Protects electrical systems
- Reduces fire hazard
- Protects the neutral conductor
- Enhances system protection
- Minimizes impact on distribution transformers
- Reduces local neutral to ground voltage
- Lowers peak phase current/average phase current
- Increases system capacity
- Decreases system losses
- Improves power factor on non-linear loads
- Reduces total harmonic distortion
- Improves phase current balance
- Augments phase voltage balance
