Mitsubishi Electric FR-A802-P Instruction Manual page 39

Main circuit terminals
Total wiring length
The total wiring length between the inverters in parallel connection and a motor must be 500 m or less. It is determined by
calculating the sum of length of "a" (a cable from the master inverter to the node point), "a' " (a cable from each slave inverter
to the node point), and "b" (a cable from the node point to the motor) in the figure. (It must be 100 m or less under Vector
control.)
Furthermore, the cable length must be 10 to 30 m between each inverter and the node point (a/a').
When driving a 400 V class motor by the inverter, surge voltages attributable to the wiring constants may occur at the motor
terminals, deteriorating the insulation of the motor. In this case, use a 400 V class inverter-driven insulation-enhanced motor.
NOTE
• Especially for long-distance wiring, the inverter may be affected by a charging current caused by the stray capacitances of the
wiring, leading to a malfunction of the overcurrent protective function or a malfunction or fault of the equipment connected on
the inverter output side.
• Refer to page 79
38
INSTALLATION AND WIRING
Example for connecting two inverters in parallel
Inverter (master)
U
V
W
Inverter (slave)
U
V
W
Total wiring length = a + a' + b
to drive a 400 V class motor by an inverter.
a
b
M
a'
500 m (100 m under vector control)