Harmonics in electrical systems can be considered as pollution of the electrical grids and can have negative effects on plant equipment.Harmonic frequencies in the power grid are a frequent cause of power quality problems including increased heating in equipment and conductors, misfiring in variable speed drives, and torque pulsations in motors.The results can be unpredictable legal and financial ramifications.
Why do harmonics occur? Harmonics are created by electronic equipment with nonlinear loads drawing in current in abrupt short pulses. The short pulses cause distorted current waveforms, which in turn cause harmonic currents to flow back into other parts of the power system.
What are the effects of harmonics? When waveforms deviate from a sinewave shape they contain harmonics. These current harmonics distort the voltage waveform and create distortion in the power system which can cause many problems. A power system can contain one or two different kinds of loads, a non-linear load or a linear load. Ultimately voltage distortions can lead to overheating of equipment, electronic equipment failure, expensive downtime, and maintenance difficulties.
Systems like ABB’s HVAC ultra-low harmonic drives are designed with built-in harmonic avoidance systems and meet low harmonic limit recommendations from IEEE519 and G5/5. Often by utilising ultra-low harmonic drives will avoid any problem caused by harmonics in the first place. ABB’s ACH580 ultra-low harmonic drive in particular help keep the current harmonics in undistorted networks below 3% under all load conditions.
How do I know if I have a harmonics issue? Look for symptoms of harmonics listed in the graph below. If one or more of these symptoms occurs with regularity, then further action will need to be taken.
Not sure if you have a harmonics issue? Contact the team for a complimentary consultation or simply advice on options available to you. Contact Control Logic on 1800 557 705 or email [email protected].