Mitsubishi Electric FR-F740 EC Instruction Manual page 237

Parameter
NOTES
Protective function by electronic thermal relay function is reset by inverter power reset and
reset signal input. Avoid unnecessary reset and power-off.
When using multiple motors with one inverter, or using a multi-pole motor or a specialized
motor, provide an external thermal relay (OCR) between the inverter and motor. And for the
setting of the thermal relay, add the line-to line leakage current to the current value on the
motor rating plate. For low-speed operation where the cooling capability of the motor redu-
ces, it is recommended to use a thermal protector or thermistor-incorporated motor.
When the difference between the inverter and motor capacities is large and the setting is
small, the protective characteristics of the electronic thermal relay function will be deterio-
rated. In this case, use an external thermal relay.
FR-F700 EC
Selection and protection of a motor
6 - 87