Output measured frequency doesn´t match with showed frequency on VSD atv320u07n4b

[remlik]

Hello,
In 5 months, I have twice replaced an atv320u07n4b that controls the motor of a conveyor belt (1HP, 460V, 1.38A, 1730rpm), due to the “SAFF” failure. The new drive has a discrepancy between the measured frequency at the output of the drive and that shown by the drive on the screen. This discrepancy was found on the replaced drive too. This drive uses CANBus for communication.

The frequency displayed on the display is 39 Hz and the measurement shows 3.6 Hz, this does not happen with the other drives where the frequencies agree.

We performed a test starting the motor directly with an AB Powerflex 525 drive and no discrepancy was found between the measured and displayed frequency of the drive.

Any suggestions?