11.10 DC Reactors (DCRs)
11-47
SELECTING PERIPHERAL EQUIPMENT
Chap 11
11.10 DC Reactors (DCRs)
A DCR is mainly used for power supply matching and for input power factor correction (for reducing harmonic
components).
■ For power supply matching
• 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 percent reactance of the power supply decreases, and harmonic
components and their peak value 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 supply exceeds 2%.
67
(V)voltageaveragephase-Three
(V)voltage Min.-(V)voltage Max.
=(%)unbalance voltageInterphase ×
■ For input power factor correction (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 supply so as to decrease harmonic
components on the power supply lines and improve the power factor of inverter. Using a DCR improves the input
power factor to approximately 86% to 95%.
• At the time of shipping, a jumper 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.
• Please select in the capacity of the applicable motor selection of DC reactor.
Figure 11.10-1 External View of a DC Reactor (DCR) and Connection Example
Power supply
Motor
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