Selection and use of Harmonic Line Reactors for PFC Capacitors installations

Main points to know: 

-If you have THD above 4% then you need to consider using a line Reactor 

- Reactors need to be selected based on the peak Harmonic Frequencies. the intention is to shift the fundamental harmonic caused by the capacitors, so as to not increase the nominal harmonics on site 

- Reactors must be placed in line with the capacitors if you wish to reduce THD

How to determine if Filter Reactor is required?

This question has no one exact suggestion. Depends on a few factor decision can be different. Modern networks are dirty of some harmonics and other influences. My recommendation is to use detuned harmonics capacitor banks even where harmonics levels are not so high.

How to select type of bank - This is not strict and 100% correct rule. This is only for information.
If part of nonlinear loads is <15% of total load, classic capacitor bank can be used
If part of nonlinear loads is >15% and <25% of total loads, classic bank can be a problematical due to amplifying of THD (total harmonics distortion). Better to be used filter capacitor bank
If part of nonlinear loads is >25% of total load, filter capacitor bank should be used.   How to define detuning factor (or resonant frequency of filter step) depends on harmonics levels:
P	THD U		THD I
5,67% (fr=210Hz)	<2%		>25%
7% (fr=189Hz)	All other conditions
14% fr=134Hz)	>4%		<15%

 

Previous recommendations are only for orientation. They are not rules for all cases.

- If Harmonics remain an issue then we suggest to consider Automatic  Harmonic Filters (AHF) Rather than a capacitor based system.

 

Selection of Filter Reactors

 

Most Common Detuning factor is 7%, then 14% then 11% which suit almost all applications. The reactor can also be custom made to suit your requirements.

Electronicon Reactor Selection Guide

For further clarification feel free to contact Fastron technical team.