2-8
2.2.2 Main circuit wiring
(1) Warning on wiring
When carrying out work on the Inverter wiring make sure to wait for at least ten minutes before you
remove the cover. Making sure to check that the charge lamp is not illuminated. A final check should
always be made with a voltage meter. After removing the power supply, there is a time delay before the
capacitors will dissipate their charge.
1. Main power terminals(R, S, T)
• Connect the main power terminals (R, S, and T) to the power supply through a electromagnetic contactor
or an earth-leakage breaker.
• We recommend connecting the electromagnetic contactor to the main power terminals. Because when the
protective function of inverter operates, it isolates the powers supply and prevent the spread of damages
and accidents.
• This unit is for the three-phase power supply. It isn’t for the single-phase power supply. If you require a
single-phase power supply unit, please contact us.
• Don't operate with on/off of the switch set up in the converter side and the inverter side. Do an operation
stop by the operation order (FW/RV) terminals
• This inverter becomes the following condition at the time of open phase because open phase protection
is being made ineffective by the early data.
R phase or T phase, open phase condition: The power isn't turned on, and it doesn't operate.
S phase, open phase condition: It becomes single-phase operation condition. Trip operation such as a
deficiency voltage or over current may be done.
Don't use it under open phase condition.
• A converter module may be damaged in the case shown below. Be careful.
When an unbalance of the power supply voltage is more than 3%.
Power supply capacity, 10 times of the capacity of inverter and a case beyond 500kVA.
When a change in the rapid power supply voltage occur.
(Example) When inverter of the plural is installed with the common electric wire whose it is short by
each other.
When there is insertion of the condenser or a removal.
• On/off of the power supply isn't to do it more than three times in one minute. It has the possibility that
inverter is damaged.
2. Inverter output terminals (U, V, and W)
• Wire with thicker wire than the applicable wire to control the voltage drop. Particularly when outputting
low frequencies, the torque of the motor will reduce by the voltage drop of the wire.
• Do not install power factor correction capacitors or a surge absorber to the output. The inverter will trip or
sustain damage to the capacitors or the surge absorber.
• In the case of the cable length being more than 20 meters, it is possible that a surge voltage will be
generated and damage to the motor is caused by the floating capacity or the inductance in the wire (400V
especially). An EMC Mains Filter is available, please contact us.
• In the case of two or more motors, install a thermal relay to each motor.
• Make the RC value of the thermal relay the value of 1.1 times of motor rated electric current. Install output
ACL when a life becomes short by the length of wiring.
3. Direct current reactor (DCL) connection terminals (PD, P)
• These are the terminals to connect the current reactor DCL (Option) to help improve the power factor.
• The short bar is connected to the terminals when shipped from the factory, if you are to connect a DCL you
Chapter 2 Installation and Wiring
