ABB DCS 500B - Page 45

Chapter 6 - Exchange of Thyristors for Size A6
DCS 500 / DCS 600 Service Manual
VI A 6 - 5
3. Write down the direction and location of the thyristors to be re-
moved and mark their gate leads. In case of BCT’s add the po-
sition of the gates.
4. Remove the gate leads if possible.
5. Loosen the mounting clamp at the top of the thyristor stack.
Figure 6-4 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!
6. Pull out both DC-busbar plates.
Figure 6-5 DC-busbar plates
DC-
busbar
plates
mountin
g
clam
p
indicatin
g
s
p
rin
g
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