Mitsubishi Electric FR-A700 Installation Manuallines page 11

PRECAUTIONS FOR USE OF THE
INVERTER
(13) Provide electrical and mechanical interlocks for MC1 and
MC2 which are used for bypass operation.
When the wiring is incorrect or if there is an electronic
bypass circuit as shown on the right, the inverter will be
damaged by leakage current from the power supply due to
arcs generated at the time of switch-over or chattering
caused by a sequence error.
(Commercial operation can not be performed with the
vector dedicated motor (SF-V5RU, SF-THY).)
(14) If the machine must not be restarted when power is restored after a power failure, provide a magnetic contactor in the
inverter's input side and also make up a sequence which will not switch on the start signal.
If the start signal (start switch) remains on after a power failure, the inverter will automatically restart as soon as the
power is restored.
(15) Instructions for overload operation
When performing an operation of frequent start/stop with the inverter, rise/fall in the temperature of the transistor element
of the inverter will repeat due to a continuous flow of large current, shortening the life from thermal fatigue. Since thermal
fatigue is related to the amount of current, the life can be increased by reducing current at locked condition, starting
current, etc. Decreasing current may increase the life. However, decreasing current will result in insufficient torque and
the inverter may not start. Therefore, choose the inverter which has enough allowance for current (up to 2 rank larger in
capacity).
(16) Make sure that the specifications and rating match the system requirements.
(17) A motor with encoder is necessary for vector control. In addition, connect the encoder directly to the backlash-free motor
shaft. An encoder is not necessary for real sensorless vector control.
9
Power supply
R/L1 U
S/L2 V
T/L3 W
Inverter
MC1
Interlock
IM
MC2
Undesirable current