ABB Relion REC670 - Section 12 Secondary system supervision; 12.1 Current circuit supervision CCSSPVC

Section 12 Secondary system supervision
12.1 Current circuit supervision CCSSPVC
IP14555-1 v5
12.1.1 Identification
M14870-1 v5
Function description IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Current circuit supervision CCSSPVC - 87
12.1.2 Application
M12395-13 v8
Open or short circuited current transformer cores can cause unwanted operation of many
protection functions such as differential, earth-fault current and negative-sequence current
functions. When currents from two independent three-phase sets of CTs, or CT cores,
measuring the same primary currents are available, reliable current circuit supervision can be
arranged by comparing the currents from the two sets. If an error in any CT circuit is detected,
the protection functions concerned can be blocked and an alarm given.
In case of large currents, unequal transient saturation of CT cores with different remanence or
different saturation factor may result in differences in the secondary currents from the two CT
sets. Unwanted blocking of protection functions during the transient stage must then be
avoided.
Current circuit supervision CCSSPVC must be sensitive and have short operate time in order to
prevent unwanted tripping from fast-acting, sensitive numerical protections in case of faulty
CT secondary circuits.
Open CT circuits creates extremely high voltages in the circuits which is
extremely dangerous for the personnel. It can also damage the insulation and
cause new problems.
The application shall, thus, be done with this in consideration, especially if the
protection functions are blocked.
12.1.3 Setting guidelines
M12397-17 v7
GlobalBaseSel : Selects the global base value group used by the function to define ( IBase ),
( UBase ) and ( SBase ).
Current circuit supervision CCSSPVC compares the residual current from a three-phase set of
current transformer cores with the neutral point current on a separate input taken from
another set of cores on the same current transformer.
The minimum operate current,
IMinOp , must be set as a minimum to twice the residual current
in the supervised CT circuits under normal service conditions and rated primary current.
1MRK 511 358-UEN A Section 12
Secondary system supervision
217
Application manual