Formulas of Related Harmonics

The following calculator computes the total harmonic current distortion (THDc or THDi), Peak Current, RMS Current, and Crest Factor based on individual harmonic current distortion values between the 1st and the 50th harmonic. Input the fundamental current and individual harmonic currents to compute THDc(THDi) also to view a waveform plot based on the input values. The waveform plot assumes all phase angles for individual current distortion values to be zero degrees (in phase with the fundamental current).

Total Harmonic Current Distortion (THDi) of a current signal is a measurement of the harmonic distortion present and is defined as the ratio of the sum of the power of all harmonic current components to the power of the fundamental frequency current. THDi is used to characterize the power quality of electric power load and the current flowing in your system's conductors. Distortion factor is a closely related term and is sometimes used as a substitute term.

For user equipment and public power distribution network, the power quality index directly affects the efficacy, service life and efficiency of equipment, and even may directly damage the electric equipment.

In accordance with Quality of Electric Energy Supply – Harmonics in Public Supply Network (GB/T 14549-1993,IEC60001), the public supply network standard is as follows:

• Improve the power factor, and save electric energy by 10%~25%;
• Reduce the inputs in capacity expansion of transformer, and extend the service life of equipment;
• Increase the operational reliability of equipment, and reduce the inputs in equipment maintenance and replacement;
• Maintain continuity and stability of production and power supply, and improve production efficiency;
• Meet national standard, and avoid the power supply management department to urge rectification and give punishment.

ZDDQ Active Harmonic Filter

• 220V Active Harmonic Filter
• 400V Active Harmonic Filter
• 480V Active Harmonic Filter
• 690V Active Harmonic Filter

Active Power Filter is a perfect comprehensive solution to power quality problems with power grid such as harmonic wave, reactive power, and three-phase load unbalance. ZD-APF active power filter is connected in parallel in 220V~480V power grid, to detect the harmonic wave in power grid in real time, generate the reverse-phase compensation current through the converter, and dynamically filter the harmonic wave in power grid. The operation of APF is unaffected by power grid structure and load type, and it will not produce harmonic oscillation with the system, thus perfectly realizing harmonic wave control of various loads. APF can also realize dynamic reactive compensation, and control the capacitor switching, to improve the power factor of power grid. Meanwhile, APF has the function of controlling the three-phase load current unbalance, thus comprehensively solving various power quality problems with power grid.