Frequency conversion motor frequency conversion motor, these experiences as a job. Overcurrent protection object of primary current with a nature of change of peak value exceeds the permissible value of frequency converter. As a result of the inverter equipment overload ability is poor, so frequency converter overcurrent protection is a vital link, so far, has been very perfect. The cause of the over current 1 homework over current in the drag system presents the over current in the process of operation. The reason for this is roughly from the following aspects: (1) motor impact load, or drive organization present & other; Stuck & throughout; Phenomenon, cause the motor current of the increase. (2) the inverter output short-circuit, such as output to the motor wire attack each other between short circuit, or motor internal short circuit, etc. (3) the inverter itself, is not normal operation, such as two of the same bridge arm in inverter bridge inverter equipment present in the process of replacement work from time to time. For example due to environment temperature is too high, or the inverter equipment itself aging, change the parameters of the inverter device attacks, cause in the process of replacement, is now conducting a equipment, and the other equipment before but could shut off, causing the same bridge arms of the upper and lower two equipment direct & throughout; The dc voltage between the positive and negative in the short circuit conditions. 2 litres of speed over current when the load of the large inertia, and set up time and too short, means in the process of acc, converter efficiency to rise too fast, the synchronous speed of the motor agile rise, and the motor rotor speed because of the large inertia load and couldn't keep up with, the result is acc current is too big. 3 speed down the over current when the load of the large inertia, and slow down set too short time, can also cause overcurrent. Due to slow down time is too short, synchronous speed agility, due to the load and the motor rotor inertia is big, still maintain a high speed, the same can be so the speed of the rotor winding cut lines over current too big to attack. 2 disposal method 1 when starting a liter of tripping speed, this is a very serious phenomenon over current, first look at (1) mechanical have stuck (2) the load side have short circuit, with a megger view to have a short circuit (3) inverter power module have damage (4) the starting torque of the motor is too small, drag system turns up 2 starting without tripping immediately, and in the process of running trip, first look at (1) set up time is too short, longer acceleration time (2) the deceleration point set is too short, longer deceleration time (3) torque compensation (U/F ratio)Set too big, cause the low frequency load current is too large of time and space (4) electronic thermal relay setting wrong, current action set is too small, misoperation caused by frequency converter
