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Can an ATV680 Active Front End drive run with unbalanced input voltage?

Issue:
ATV680 running with unbalanced input voltage

Product Line:
Altivar 680 Process Drives

Environment:
All

Cause:
Site line voltage is unbalanced

Resolution:
It is NOT recommended to operate an ATV680 AFE on a 480V power system with a voltage unbalance of 4% to 7.5%. This is far outside the specification of the drive.
The mains voltage must comply with the requirements according to IEC 60038 and EN 50160:
- Unbalance between phases: < 2 %
- Total harmonic factor THD(v): < 10 %
- Maximum single harmonic: < 5 %
With this supply voltage the drive complies with the specified THDi value.

If the voltage unbalance is 2 … 4% the drive will work but the THDi value will be higher than specified. A voltage unbalance of more than 4% will harm the drive. The input IGBT might overheat and/or the fuses might blow due to unsymmetrical input current. There is also a risk of oscillations if the voltage controller is not able to keep DC bus voltage constant.