Chapter 8 - Changing Diodes and IGCTs in 7/9 MVA Phase Modules ABB
8-12 (18) 3BHS202077 ZAB E01 Rev. C ACS 6000 Maintenance Manual
3 Continue with section
Removing Lower NP Diode
if the lower diode
has to be replaced.
If not, continue with section
Assembling the Stack
.
Removing Lower NP
Diode
After the steps of section
8.4.1 Preparatory Steps
and section
Removing
Upper NP Diode
(up to step
3
) have been carried out do the following:
4 Lift the cooler and the busbar above the NP diode with one hand and
extract the diode from the stack with the other hand.
Figure 8-17 Extracting Lower NP Diode
Assembling the Stack
1 Check the contact surfaces of the new diode(s) and the coolers for
any dirt.
If necessary, clean the contact surfaces with an appropriate solvent
(e. g. alcohol). Using a fluff-free cloth wipe the surfaces paying
attention not to scratch the surfaces.
Note: Do not use any grease or any electrical joint compound.
2 Place the diode(s) in the stack and center it (them).
Pay attention to the correct polarity particularly when exchanging
diodes from different suppliers. Always verify the polarity with the
corresponding wiring diagram.
3 Turn the u-shaped busbar back into place and connect it to the top
perforated busbar.
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