APF Principle
Delta’s PQC Series APF is connected in parallel with non-linear loads, and uses one set of current transformers (CT) to detect the load current. It calculates each order harmonic current by FFT algorithms in its DSP microchips, and then generates a compensating current with the same amplitude but opposite phase angles to the detected harmonic current, which cancels out the original load harmonics.
The PQC series APF not only eliminates harmonic current from the load side, but it also mitigates harmonic voltage caused by harmonic currents. The APF system can also improve power factor (PF) and correct load imbalances in the power system.
Modular APF
APF modules and an LCM panel can be embedded in Delta’s standard APF cabinet or a customized cabinet. There are breakers, cable terminals and Surge Protection Device (SPD) in the APF cabinet.
According to cable terminal type, a modular APF can be divided into two types:
- Draw type modular APF (hot-swappable)
- Fixed type modular APF (not hot-swappable)
APF Compensation Performance
Delta’s PQC Series APF can perfectly mitigate harmonic current, and suppress harmonic voltage caused by the harmonic current. When the APF capacity is sufficient and background harmonic voltage is low, the APF ensures excellent compensation performance at full load condition, as below:
- THDu (Total Harmonic Distortion of Voltage) < 3%
- THDi (Total Harmonic Distortion of Current) < 5%
- PF (Power Factor) = 0.99 (improves both leading and lagging PF)
- Neutral Current Attenuation Ratio ( [IN(Before) - IN(After)] / IN(Before) ) >95%