ABB DCS 500B - Install New Thyristor

Chapter 9 - Exchange of Thyristors for Size C4
DCS 500 / DCS 600 Service Manual
VI A 9 - 3
mountcl_c4.dsf
Mounting clamp
Disassembly tool
Front view
View from
the right
View from
the left
Figure 9-1 How to use the disassembly tool (at a left thyristor
stack of a converter)
Install new thyristor
- Ensure that the new thyristor is of the correct type (see Appen-
dix A). Keep the semiconductor and its surroundings clean. If
necessary clean them with a piece of tissue paper moistened
with solvent.
Note: Do not touch the polished surfaces of the thyristor.
- Clean the polished surfaces of the semiconductor with a piece of
tissue paper moistened with solvent. Dry all surfaces. Spread a
thin layer of heat conducting paste on both sides of the thyristor,
if necessary use a rubber spatula.
- Connect the gate leads if possible.
- Clean all parts with tissue paper moistened with solvent, witch
have had or will have contact with the thyristor or each other
(lower / upper heat sink). Do not clean the surfaces of grease too
thoroughly, because the aluminium surfaces will oxidise in a few
seconds. Dry all surfaces.
- Push the thyristor until it snaps into its mounting clamp.
Note: Be sure that the thyristor is installed in the right direction.
Do not pinch or cut the gate leads or any other cable.
- Turn the thyristor so that the gate leads point in the right direc-
tion.
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