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Exchange thyristors size H7
3ADW000488R0101 DCS880 Service manual e a
Find faulty thyristor modules
1. Check the branch fuses by performing an OHM test.
2. Find the defective branches by performing an OHM test (both polarities) between U1, V1, W1 and C1, D1.
Bridge configuration H5 … H8
3. Disconnect the branching fuses of the defective branches.
4. Find the defective thyristors by performing an OHM test (both polarities) over their heat sinks.
5. In a 4-quadrant converter with BCTs change the BCT.
6. In a 4-quadrant converter with 2 single thyristors exchange both thyristors clamped between the same
heatsinks.
Note:
Because “Disc Type” semiconductors need a certain compression force to operate properly, a measurement
outside the clamped heat sinks might be wrong.
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