Chapter 2 Installation and Wiring
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15
2.4.2 Main Circuit Wiring
operation
Be sure that the motor is running forward when the running direction command of ac
drive is forward. If the motor is running reverse, interchange any two-output terminals
(U, V, W) can change the rotate direction of the motor, and you can change function code
P2.25 to change phase-sequence of the motor.
Never connect input power supply cables to output terminals, or else parts of the ac drive
would be damaged. Do not connect output terminals to earth, be sure output cables not
touch to the shell or be shorted, or else the ac drive would be damaged.
Be sure Earth terminal “PE” is connected to earth. The earthling resistance of 380V-class
should be below 10Ω. Be sure the earthling not be shared with an electric welding
machines or other high-current electrical equipments. Use ground wiring as mentioned
in “Appendix 3 Main Circuit Output Cable Selection” and keep the length as short as
possible.
When two or more ac drives are used at the same time,
do not loop the wires. The right
and wrong earthling connection methods are shown as Figure 2-9.
Inverter
InverterRight
Inverter
InverterInverter
Wrong
Inverter
Fig 2-9 Earthling Connection Method
Attention: The neutral point of motor using Y connection can’t be connected to
earth.
Since the
ac drive output PWM wave, if a capacitance for improving power factor or a
lightning varistor is installed on the output side, which would case tripping or damage to
parts, be sure to remove it.
If a contactor or other on-off part is needed to be installed between the output and the
motor, be sure the on-off operation is done when the ac drive has no output, otherwise the
ac drive would be damaged.
Countermeasures to conduction interference: To inhibit conduction interference of the
output, besides installing noise filter and using shielded motor cables, leading all the
output cables to earthling metal tube is also a method. Make the distance between the
output cables and the control signal cables greater than 30 cm, the effect of conduction
interference will obviously decrease too.
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