ABB Relion 670 Series Applications Manual page 233

1MRK 511 401-UEN Rev. K
Section 10
10.1 Shunt capacitor cascading failure protection
SCCFPVOC
10.1.1 Identification
Function description
Shunt capacitor cascading failure
protection
10.1.2 Application
High voltage shunt capacitor banks (SCB) are normally constructed using individual capacitor
units connected in series and/or parallel to obtain the required voltage and MVAr ratings as
shown in
must be insulated from each other by insulators because the capacitor casing within the rack
is seated at a certain potential.
Capacitor unit (can)
One phase
of the SCB
IEC19000105 V1 EN-US
Figure 105: Capacitor bank arrangement
A cascading failure is a type of series fault as shown in
protection will be insensitive to these types of series faults. The fault current drawn from the
system for the faults is also limited by the impedance of the remaining healthy parts of the
SCB, thus the standard SCB over-current protection will not detect it either. The unbalance
voltage/current protection which is typically available within the SCB protection scheme is
designed to detect an element failure within a capacitor unit. Thus, with a proper design it
Bay control REC670
Application manual
Unbalance protection
Figure 105. Typically, the neighboring capacitor units are installed in racks. Each rack
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IEC 61850 IEC 60617
identification identification
SCCFPVOC 2(I > /U <)
Figure
Unbalance protection
GUID-08928884-88E3-4A40-9B50-BDA5F1A451D9 v1
GUID-86BB3D32-8E40-48FB-8619-8D0B28B60AFA v1
ANSI/IEEE C37.2 device
number
51 V
GUID-CFD57EFD-6F79-4C9F-BAB7-C110EECD06D4 v1
IEC19000105-1-en.vsdx
106. Any SCB differential
Section 10
Capacitor rack
227