Siemens · SINAMICS G120
Significant voltage ripple has been detected on the DC link of the inverter. This can be caused by issues with the input power supply, damaged DC link capacitors, or an internal power circuit problem. Large ripples lead to unstable operation and potential damage to the inverter's power components, risking system failure.
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Measure the incoming three-phase AC voltage (e.g., L1-L2, L2-L3, L3-L1) at the drive's input terminals and verify phase balance (e.g., within 2% of nominal).
Inspect the DC-link capacitors visually for signs of bulging, leakage, or overheating.
Check the sizing and condition of any installed line reactors (e.g., L1, L2, L3 reactors) upstream of the drive.
With the drive powered, observe the DC-link voltage (e.g., via drive display or test points) to quantify the ripple using an oscilloscope if available.
Ensure the drive's input power source is adequately sized and stable, checking for voltage sags or swells on the supply line.