The object of overcurrent protection in the frequency converter mainly refers to the case where the peak value of current exceeds the allowable value of the frequency converter with abrupt nature.
Due to the poor overload capacity of the inverter, the overcurrent protection of the inverter is a crucial part. So far, it has developed very well. (1)
Cause of overcurrent 1. Overcurrent occurs during operation, I . e. dragging the system during operation.
The reasons come from the following aspects: 1 The Motor encounters an impact load, or the transmission mechanism is 'stuck', causing a sudden increase in the motor current.
(2) the output side of the frequency converter is short-circuited, such as the connecting line between the output end and the motor is short-circuited to each other, or the motor is short-circuited inside, etc.
(3) the inverter itself is not working properly, such as the two inverter parts of the same bridge arm in the inverter bridge are abnormal during the continuous alternating working process.
For example, due to excessive ambient temperature or aging of the inverter itself, the parameters of the inverter are changed, resulting in the alternation process, one device has been turned on while the other device has not yet been turned off, causing 'straight-through' of the upper and lower devices of the same bridge arm, leaving the positive and negative poles of the DC voltage in a short circuit state.