Mitsubishi Electric FR-A741-5.5K Installation Manualline page 16

PRECAUTIONS FOR USE OF THE INVERTER
Instructions for overload operation
When performing operation of frequent start/stop of the inverter, increase/decrease in the temperature of the transistor
element of the inverter may 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 bound current, starting
current, etc. Decreasing current may increase the life. However, decreasing current will result in insufficient torque and
the inverter may not start. Therefore, increase the inverter capacity to have enough allowance for current.
Make sure that the specifications and rating match the system requirements.
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.)
When the motor speed is unstable, due to change in the frequency setting signal caused by electromagnetic noises
from the inverter, take the following measures when applying the motor speed by the analog signal.
– Do not run the signal cables and power cables (inverter I/O cables) in parallel with each other and do not bundle them.
– Run signal cables as far away as possible from power cables (inverter I/O cables).
– Use shield cables as signal cables.
– Install a ferrite core on the signal cable (Example: ZCAT3035-1330 TDK).
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