Reason one: motor load is too heavy
1 the motor load is too heavy, so that the frequency converter over a long period of its rated current. Need to choose the motor power to match the frequency converter.
2 motor shaft mechanical clamping, motor block, frequency converter current limiting action, the current limit amplitude is less than 120%.
Reason two: inverter use ambient temperature is too high
When the ambient temperature exceeds the allowable value of the converter, the rated operating temperature may exceed the maximum permissible temperature.