Danfoss Active Power Filter

Inverter Danfoss Active Power Filter

What are harmonics?
Why are harmonics a challenge?
An electrical AC supply is ideally a pure sine wave of either 50 or 60 Hz fundamental frequency and all electrical equipment is designed for optimal performance on this supply.

Harmonics are voltages and currents which have frequency components that are integers multiple of the fundamental frequency – polluting the pure sinusoidal waveform.

Power electronics such as those used in rectiers, variable speed drives, UPS, lighting dimmer switches, televisions, and other equipment, draw a nonsinusoidal current from the grid.

This non-sinusoidal current interacts with the mains supply and distorts the voltage to a greater or lesser degree depending upon the strength or weakness (fault level) of the supply.

Generally, the greater the amount of installed electronic power-switching equipment on-site, the greater the
degree of harmonic distortion.

Excessive harmonic distortion of the mains supply implies that the source not only carries 50 or 60 Hz frequencies but also higher frequency components.

These components can not be utilized by electrical equipment and adverse eects can be severe and include:

Limitations on supply and network utilization
Increased transformer, motor and cable heating
Reduced equipment lifespan
Unexpected costly production stops
Control system malfunctions
Circuit breaker trips without cause
Pulsating and reduced motor torque
Abnormal and excessive noise from transformers, bus bars, motors, etc.
Frequent reactive compensation capacitor faults: Failure to work properly, even overheating, deforming, exploding