Chapter 7 - Exchange of Thyristors for Size A7
VI A 7 - 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
).
2. Remove the AC busbars, of the defective branches.
4-quadrant converter:
3. Remove all screws of the DC - busbars either above or below
the fuses of the defective branches.
Note: The connection is made with a screw socket, which may
fall down, when all screws are removed.
Figure 7-1 Location of busbars
4. Put a small piece of isolator (e.g. paper) between the DC - bus-
bar and the heat sink to insulate the anti parallel thyristors from
each other.
5. Find the defective thyristors by performing an OHM test (both
polarities) over their heat sinks.
2 - quadrant converter:
3. Find the defective thyristors by performing an OHM test (both
polarities) over their heat sinks.
DC busbars
removed
screws
loose AC busbar
Isolator
3ADW000093R0701_DCS500B/DCS600_Service manual_e_g
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