Design
Chapter 3
Determining the Wire Size
Determine the wire size for the main circuit so that line voltage drop is within 2% of the
rated voltage.
Line voltage drop VD is calculated as follows:
VD (V) = p3 x wire resistance (Ω/km) x wire length (m) x amperage (A) x 10–3
H Wiring on the Input Side of Main Circuit
D Installing a Molded-case Circuit Breaker
Always connect the power input terminals (R, S, and T) and power supply via a molded-
case circuit breaker. Power must be supplied instantaneously. Unstable power startup
will not start the Inverter.
D Installing a Ground Fault Interrupter
If a ground fault interrupter is to be connected to the wire on the primary side (R, S, and
T) of the main circuit, use either of the following interrupters to prevent malfunctions:
• Ground fault interrupter with a sensitivity amperage of 200 mA or more and with an
operating time of 0.1 second or more
• Ground fault interrupter with high-frequency countermeasures (for Inverter)
D Installing a Magnetic Contactor
This Inverter can be used without a magnetic contactor (MC) on the power supply side.
If the power supply for the main circuit is to be shut off because of the sequence, a mag-
netic contactor can be used instead of a molded-case circuit breaker.
However, when a magnetic contactor is installed on the primary side of the main circuit
to forcibly stop a load, note that regenerative braking does not work and the load coasts
to a stop.
• A load can be started and stopped by opening and closing the magnetic contactor on
the primary side. Note, however, that frequently opening and closing the magnetic
contactor may cause the Inverter to break down.
• When the Inverter is operated with a Digital Operator, automatic operation cannot be
performed after recovery from a power interruption.
D Connecting Input Power Supply to the Terminal Block
Because the phase sequence of input power supply is irrelevant to the phase sequence
(R, S, T) of the terminal block, input power supply can be connected to any terminal on
the terminal block.
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