ABB REB670 Series, Applications Manual

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Capacitor Unit
(Can)
Rack
IEC09000753_1_en.vsd
IEC09000753 V1 EN-US
Figure 113: 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
Which type of fusing is used may depend on can manufacturer or utility preference and
previous experience.
Because the SCBs are built from the individual capacitor units the overall connections may
vary. Typically used SCB configurations are:
1. Delta-connected banks (generally used only at distribution voltages)
2. Single wye-connected banks
3. Double wye-connected banks
4. H-configuration, where each phase is connected in a bridge
Section 7 1MRK 505 370-UEN D
Current protection
202 Busbar protection REB670
Application manual