ABB DCS880 - Setup Procedures; Pre-Power On Checks; Power On and Initial Verification

21
Fault Tracing Thyristors
3ADW000488R0101 DCS880 Service manual e a
Ripple monitor
If the ripple monitor fault occurred, a fault tracing as described above must be carried out:
− Check the fuses and the thyristors, according to the statements before.
− If the power section seems to be ok, but still one or more thyristors don’t take current, something went
wrong in between the firing pulse generation and the thyristor’s gate; in this case check:
− Is a firing pulse present on the primary side of the firing pulse transformer?
− Is a firing pulse present on the secondary side of the firing pulse transformer?
− Is the firing pulse transferred to the gate of the thyristor (loose gate connector)? Are all electrical
connections still healthy?
− Can the thyristor be fired with the applied firing pulse? Is the pulse form of the firing pulse identical at
all measuring positions?
− Check the settings of the current controller.
− Check the AC mains network by taking recordings of the line voltage and current at all 3 phases at the same
time.