ABB SDCS-AMC-CLAS2｜Control Module for Industrial｜

SDCS-AMC-CLAS2

Ripple monitoring fault Ripple monitor
Fault meaning: The ripple amplitude of the DC current far exceeds the normal value, and the vast majority of reasons are that the single thyristor stops working.
The failed thyristor no longer outputs current, resulting in a significant drop in DC current.
The current loop controller will drive the remaining thyristors to output overcurrent, compensate for current drop, and maintain the average current unchanged:
Electric mode (trigger angle α ≤ 90 °): Compensation action directly reports ripple monitoring fault.
Braking/inverter feedback mode: Most of them directly cause the fuse to burn out.
Four types of causes of no output current in thyristors
The branch fuse is blown, and one of the six thyristors is disconnected.
Only applicable to high-power models 900-5200A (equipped with 6 internal branch fuses); The model is equipped with three external AC fuses, and if any one phase fuse is blown, the entire machine will be completely shut down.
The thyristor did not receive the trigger pulse.
The parameters of the current controller are severely mismatched with the DC load.
AC power grid side issues: phase offset asymmetry, three-phase voltage imbalance; Insufficient design margin for power factor compensation and harmonic control equipment.
🔧 Suggested troubleshooting sequence (available for business/maintenance)
Check all fuses, parallel fuses must be replaced as a whole, not just damaged parts
Check each thyristor to confirm if there is breakdown or open circuit
Confirm the triggering pulse output of the thyristor (check the SDCS-AMC-DC-CLAS2 control board and pulse circuit)
Check if there is a short circuit on the DC side and if the load matches the controller parameters
Measure the three-phase voltage and phase of the AC power grid, investigate the effects of reactive power compensation and harmonic equipment