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[ 2 ] DC reactors (DCRs)
A DCR is mainly used for power supply normalization and for supplied power factor improvement
(for reducing harmonic components).
For power supply normalization
- Use a DCR when the capacity of a power supply transformer exceeds 500 kVA and is 10 times or
more the rated inverter capacity. In this case, the percentage-reactance of the power source
decreases, and harmonic components and their peak levels increase. These factors may break
rectifiers or capacitors in the converter section of inverter, or decrease the capacitance of the
capacitor (which can shorten the inverter's service life).
- Also use a DCR when there are thyristor-driven loads or when phase-advancing capacitors are
being turned ON/OFF.
- Use a DCR when the interphase voltage unbalance ratio of the inverter power source exceeds 2%.
67
V)(voltageaveragephase-Three
V)( voltageMin.V)( voltageMax.
=%)(unbalance voltageInterphase ×
−
For supplied power factor improvement (for suppressing harmonics)
Generally a capacitor is used to improve the power factor of the load, however, it cannot be used in a
system that includes an inverter. Using a DCR increases the reactance of inverter's power source so as
to decrease harmonic components on the power source lines and improve the power factor of inverter.
Using a DCR improves the input power factor to approximately 95%.
• At the time of shipping, a short bar is connected across terminals P1 and P (+) on the
terminal block. Remove the jumper bar when connecting a DCR.
• If a DCR is not going to be used, do not remove the jumper bar.
For three-phase 200 V/400 V or single-phase 200 V
For single-phase 100V
Figure 6.9 External View of a DC Reactor (DCR) and Connection Example
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