The reactance rate refers to the percentage of the rated capacity of a series reactor to the rated capacity of a capacitor, or the percentage of the inductive reactance Xln of a series reactor to the capacitive reactance Xcn of a capacitor.

The selection of reactance rate also depends on the harmonic background:

1. The background harmonic at the connection point of the capacitor device is 3rd order

1) The third harmonic content is relatively small, and a series reactor with a range of 0.1% to 1% can be selected. However, it should be verified whether the amplification of the third harmonic exceeds or approaches the national standard limit after the capacitor device is put into operation, and there should be a certain margin.

2) The third harmonic content is relatively high and has exceeded or approached the national standard limit. Therefore, a mixed installation of 12% or 13% and 4.5% to 6% series reactors is selected.

2. The background harmonics at the connection point of the capacitor device are 3rd and 5th order

1) The content of the 3rd harmonic is very small, and the content of the 5th harmonic is relatively high (including those that have exceeded or are close to the national standard limit). Choose a series reactor with 4.5% to 6%, and avoid using a series reactor with 0.1% to 1%.

2) The third harmonic content is slightly higher, and the fifth harmonic content is smaller. Therefore, a series reactor with a range of 0.1% to 1% should be selected. However, it should be verified whether the amplification of the third harmonic exceeds or approaches the national standard limit after the capacitor device is put into operation, and there should be a certain margin.

3) The third harmonic content is relatively high and has exceeded or approached the national standard limit. Therefore, a series reactor with 12% or a combination of 12% and 4.5% to 6% is selected for installation.

3. The background harmonic at the connection point of the capacitor device is 5th order or above

1) The 5th harmonic content is relatively small, and a series reactor with 4.5% to 6% should be selected.

2) The 5th harmonic content is relatively high, and a 4.5% series reactor should be selected.

4. For series reactors with a range of 0.1% to 1%, it is necessary to prevent severe amplification or resonance of the 5th and 7th harmonics; For the use of 4.5% to 6% series reactors, it is necessary to prevent severe amplification or resonance of the 3rd harmonic.