Find Faulty Thyristor - ABB DCS 500 Series Service Manual

Chapter 5 - Exchange of Thyristors for Size A5

Find faulty thyristor

VI A 5 - 2
1. Find the defective branches by performing an OHM test (both
polarities) between U1, V1, W1 and C1, D1 (see figure 5-1 )
U1
V1
W1
Figure 5-1 Basic B6-bridge with branching fuses
2. Disconnect the branch fuses of the defective branches.
3. Find the defective thyristors by performing an OHM test (both
polarities) over their heat sinks.
4. In a 4 - quadrant converter change both thyristors clamped be-
tween the same heatsinks at once.
Note: Because "Disc Type" semiconductors need a certain
compression force to operate properly a measurement outside
the clamped heat sinks might be wrong. To be sure change only
one thyristor, clamp the heat sinks again and repeat step three.
3ADW000093R0601_DCS500B/DCS600_Service Manual_e_f
C1 (+)
branching fuse
branch
D1 (-)
DCS 500 / DCS 600 Service Manual