Chapter 5 - Exchange of Thyristors for Size A5
VI A
5 - 2
DCS 500 / DCS 600 Service Manual
Find faulty thyristor
1.
Find the defective branches by performing an OHM test (both
polarities) between U1, V1, W1 and C1, D1 (see
figure 5-1
)
C1 (+)
D1 (-)
U1
V1
W1
branching fuse
branch
F11
F13
F15
F14
F16
F12
V11
V13
V15
V24
V26
V22
V14
V16
V12
V21
V23
V25
principle_B6_a.dsf
Figure 5-1
Anti-parallel B6-bridges 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.
3ADW000093R0701_DCS500B/DCS600_Service manual_e_g