In daily work, we may encounter situations where the frequency converter does not respond after being powered on. Generally speaking, if a frequency converter malfunctions, it will display the corresponding fault code. So, what could be the reason for no response? Then how should it be investigated?

1.Investigation method

(1). Check the power switch: First, confirm the power-on status of the power switch. A problem with the power switch can cause the frequency converter to fail to start normally. Just replace the switch.

(2). Static test: Use a multimeter to measure the resistance value of the frequency converter. Set the multimeter to the X10 resistance range, connect the red probe to the P terminal of the frequency converter, and connect the black probes to R, S, and T in sequence. The measurement result is approximately a resistance value of several tens of ohms and is basically balanced. Next, they are swapped. Connect the black test lead to the P terminal and the red test lead to R, S, and T in sequence. The measurement result will be a resistance value close to infinity. Then connect the red test lead to the N terminal and repeat the above process. If the results are the same, the static test is normal.

(3) Dynamic test: Start the frequency converter under no-load conditions and observe the output voltages of U, V, and W phases. Check for issues such as phase loss or three-phase imbalance, which might be due to faults in components like modules or driver boards. If the output voltage is normal, further load testing is required.

2.Solution

(1). Power failure: Check if the power supply is normal and ensure it can be connected properly.

(2). Incorrect parameter settings: Verify that the parameter settings of the frequency converter match the motor.

(3). Issues with external control signals: Confirm that the external control signals, such as from a PLC or other control devices, are normal.

(4). Module or driver board failure: Problems like phase loss or three-phase imbalance during dynamic testing are typically due to module or driver board failures.