66
Exchange of Thyristors for Size D7
3ADW000195R0501 DCS800 Service Manual e e
Find faulty thyristor
1. Find the defective branches by performing an OHM test (both polarities)
between U1, V1, W1 and C1, D1 (see picture Anti-parallel B6-bridges with
branching fuses on page 45).
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.
Location of busbars
4. Put a small piece of isolator (e.g. paper) between the DC - busbar 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
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