ABB Relion REC670, Applications Manual

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Capacitor Unit
(Can)
Rack
IEC09000753_1_en.vsd
IEC09000753 V1 EN-US
Figure 92: Replacement of a faulty capacitor unit within SCB
There are four types of the capacitor unit fusing designs which are used for
construction of SCBs:
Externally
fused
where an individual fuse, externally mounted, protects each capacitor unit.
Internally
fused
where each capacitor element is fused inside the capacitor unit
Fuseless where SCB is built from series connections of the individual capacitor units (that is,
strings) and without any fuses
Unfused where, in contrary to the fuseless configuration, a series or parallel connection of the
capacitor units is used to form SCB, still without any fuses
1MRK 511 401-UUS A
Section 8
Current protection
Bay control REC670 2.2 ANSI 229
Application manual