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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-3
V)( voltageMin.V)( voltageMax.
=%)(unbalancevoltageInterphase u
■ 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%.
x 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.
x If a DCR is not going to be used, do not remove the jumper bar.
㩷
For three-phase 230 V/460 V or single-phase 230 V
Figure 6.9 External View of a DC Reactor (DCR) and Connection Example
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