Chapter 2 - Checking IGCTs and Diodes ABB
2-4 (6) 3BHS202077 ZAB E01 Rev. C ACS 6000 Maintenance Manual
4 Switch on the auxiliary power to the gate unit.
5 Switch on the power supply of the INT board to apply a constant light
to the IGCT.
6 Measure the voltage between gate and cathode.
Expected result of the measurement: approx. +0.7 VDC (see also
Figure 2-2
).
Note: It is important that the following steps 5 and 6 are carried out in the
stated sequence to prevent damage of the gate unit.
7 Disconnect the auxiliary power.
8 Disconnect the temporary fiber optic cable.
9 Reconnect the original fiber optic cable.
10 Switch on the auxiliary power supply.
11 Wait approx. 20 sec until both LEDs on the gate unit have lighted up.
To test a diode the phase module needs to be disconnected from the
busbar connectors. Water hoses, optical fibers and gate unit power supply
leads can stay in place. The diodes can be accessed from the front of the
phase module.
1 Deenergize and ground the ACS 6000.
2 Switch off the auxiliary power supply.
3 Remove the two fastening bolts at the bottom on each side of the
phase module.
4 Disconnect the phase module from the rear busbar connectors. Pull
it towards the front of the cabinet until the lower water hose just
touches the support frame (see circle in
Figure 2-4
).
5 Check that the phase module is completely disconnected from the
busbar connectors.
Note: When pulling out the phase module take care that fiber optic cables
and gate unit supply leads are not damaged.
2.3 Checking Diodes in 7/ 9 MVA Phase Modules
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