There are three kinds of fault signals of frequency converter:

(1) Mechanical overload: the main feature of overload is motor heating, and can be found by reading the running current from the display screen. The main reasons are that the load of frequency converter is too large, the acceleration and deceleration time and the operation cycle time are too short; the voltage of V / F characteristic is too high; the power of frequency converter is too small.

(2) Three phase voltage imbalance: it causes excessive operating current of a certain phase, resulting in overload trip. Its characteristic is unbalanced heating of motor, which may not be found when reading the running current from the display screen (because only one phase current is displayed on the display screen).

(3) Misoperation: the current detection part inside the frequency converter breaks down, and the detected current signal is too large, resulting in tripping.

The fault signal processing method of frequency converter is as follows:

(1) Check whether the motor is hot.

If the temperature rise of the motor is not high, first check whether the load size, acceleration and deceleration time, and operation cycle time are reasonable, and correct the V / F characteristics, check whether the electronic thermal protection function of the frequency converter is preset reasonably. If the inverter has a margin, the preset value of the electronic thermal protection function should be relaxed; if the allowable current of the frequency converter has no margin, it can not be relaxed And according to the production process, the overload is normal overload, which indicates that the selection of frequency converter is improper, the capacity of frequency converter should be increased and the frequency converter should be replaced. This is because when the motor is dragging variable load or intermittent load, as long as the temperature rise is too high, and the overload is normal overload, it means that the load of the motor is too heavy. At this time, it is necessary to consider whether the transmission ratio can be properly increased to reduce the load on the motor shaft. If it can be increased, the rotation ratio shall be increased; if the transmission ratio cannot be increased, the motor capacity shall be increased.

(2) Check whether the three-phase voltage on the motor side is balanced.

If the three-phase voltage on the motor side is unbalanced, then check whether the three-phase voltage at the output end of the inverter is balanced. If the problem is in the inverter, the inverter module and its driving circuit of the inverter should be checked. If the voltage at the output end of the frequency converter is balanced, the problem occurs in the circuit from the inverter to the motor. Check whether the screws at all terminals have been installed Fastening, and whether the contact state of the contact is good.