2-17
2-2 Wiring
2
Design
Installing a Magnetic Contactor (MC)
•If the power supply of the main circuit is shut off due to sequencing, a magnetic contactor (MC) can
be used. (When forcibly stopping the load with an MC on the primary side of the main circuit,
however, the regenerative braking does not work and the load coasts to a stop (free run).)
•Frequently opening and closing the magnetic contactor (MC) to start and stop a load may cause
the Inverter to break down. To extend the life of the Inverter's internal electrolytic capacitor, limit
the frequency to no more than once every 30 minutes.
Connection Sequence to the Terminal Block
•Input power supply can be connected to any terminal because the phase sequence of the input
power supply is irrelevant to that of the terminal block (R/L1, S/L2, and T/L3).
Installing an AC Reactor
•If the Inverter is connected to a large-capacity power transformer (660 kVA or more) or the phase
advance capacitor is in use, a large peak current may flow through the input power circuit, causing
the converter unit to break down.
•Install an optional AC reactor on the input side of the Inverter. An AC reactor will also improve the
power factor of the power input side.
Installing a Surge Absorber
•Always use a surge absorber or diode when magnetic contactors (MC), electromagnetic relays,
solenoid valves, solenoid, and magnetic brakes are used.
Connecting a Regenerative Braking Unit
When running a load with a large inertia or a vertical axis, regenerative energy will return to the
Inverter.
If overvoltage in the main circuit is generated during deceleration, this indicates that the
regenerative energy exceeds the capacity of the Inverter. In this case, use a regenerative braking
unit.
Select a regenerative braking unit referring to the allowable operation cycle of the regenerative
braking unit specifications regardless of the Inverter capacity.
When using a braking resistor with the resistor of a regenerative braking unit removed, refer to the
connectable resistance of the regenerative braking unit and the allowable braking frequency of the
braking resistor in making a selection.
Refer to “ 7-5 Options” (page 7-14 to 16) for further information when making a selection.
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