Necessary Knowledge When Frequency Converter Failure(II)

Dynamic test: after stating the test result is normal, can carry on the dynamic test, namely on the electric test machine. Before and after power up, we must pay attention to the following points: before power up, we must confirm whether the input voltage is incorrect or not, and the 380V power supply will appear in 220V inverter (exploding capacitance, varistor, module, etc.). Check whether the frequency converter is connected correctly or not, whether the connection is loose, the abnormal connection may sometimes lead to the frequency converter malfunction, serious explosion machine and so on. After the power on, the fault display content is detected, and the fault and its cause are preliminarily determined. If there is no fault, first check whether the parameters are abnormal or not, and after the parameters are reverted, start the inverter under the condition of no load (not connected with the motor), and test the three phase output voltage of U, V, W. If there is a lack of phase, three-phase imbalance and so on, the module or drive board has trouble. In the case of normal output voltage (no phase, three-phase balance), load testing, as far as possible full load test. .

Fault determination: rectifier module damage. It is usually caused by a grid voltage or an internal short circuit. Replace the rectifier bridge when the internal short circuit is eliminated. When dealing with the fault on the spot, we should focus on checking the situation of the user power network, such as the voltage of the power network, whether there are electric welding machines and other equipment that pollute the power network, and so on. .

Inverter module damage is usually caused by motor or cable damage and drive circuit failure. After repairing the drive circuit, replace the module when the driving waveform is in good condition. After replacing the drive board in the field service, pay attention to check the motor and connection cable. The frequency converter can be operated only if there is no fault. .

When your inverter power up is usually due to switching power loss or soft charge circuit damage to the DC circuit without direct current caused, such as starting resistance damage, operation panel damage will also cause this situation. Display overvoltage or undervoltage is usually due to input phase deficiency, circuit aging and circuit board moisture. The solution is to find out the voltage detection circuit and the detection point, and replace the damaged device. Display overcurrent or grounding short circuit is usually due to current detection circuit damage. Such as Hall components, operational amplifier circuit, etc.