What are the causes of input current unbalance on ATV71 drive.
(1) Example: input current R=190, Y=215, B=216 at the input side of drive.
To know, if the problem comes from the ATV61 or from the main supply; this can be done if you inverse R and Y and perform the measurement of current. If the current in R becomes equal to 215 and the current in Y is 190, it means that the problem comes from the main supply.
(2) The balance of the current depends on the supply characteristics:
An unbalanced input current may be caused by an unbalanced main supply voltage. We say that the unbalance voltage do not exceed 1.8% of the nominal voltage. Please check it.
(3) Perhaps other devices are unbalanced or connected between two phases or phases and neutral.
(4) The input phase unbalance may be caused by a too small power for the main transformer. The transformer must be 2 times minimum the power of the drive.
(5) Make confirm cable size is same for all 3 phases, as impedance network can cause unbalance of phase input current.