Chapter 7 - Exchange of Thyristors for Size A7
DCS 500 / DCS 600 Service Manual
VI A
7 - 3
Remove faulty thyris-
tor
1. Remove the screws of all DC / AC - busbars preventing the
stack to be prized open. Remove the branch fuses, if the defec-
tive thyristors are covered by them.
Note:
It depends on the location of the defective thyristors,
which DC / AC - busbars have to be disconnected.
2.
Loosen the screws holding the backplate and make sure the
backplate can move up.
Figure 7-2
Backplate
3. Write down the direction and location of the defective thyristors
to be removed and mark their gate leads.
4. Remove the gate leads if possible.
5. Loosen the mounting clamp at the top of the thyristor stack.
Figure 7-3
Handling of indicating spring and mounting clamp
Attention:
While loosen the mounting clamp the indicating spring
must be pulled out a little, otherwise the spring will be damaged!
Do not remove the nuts totally, otherwise the treaded rods will fall
down!
screws
backplate
mounting clamp
indicating spring
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