ABB ret650, Applications Manual

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Section 10 Secondary system supervision
10.1 Current circuit supervision CCSSPVC
IP14555-1 v5
10.1.1 Identification
M14870-1 v5
Function description IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Current circuit supervision CCSSPVC - 87
10.1.2 Application
M12395-13 v9
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.
10.1.3 Setting guidelines
M12397-17 v8
GlobalBaseSel : Selects the global base value group used by the function to define
IBase , UBase and SBase as applicable.
1MRK 504 169-UEN A
Section 10
Secondary system supervision
Transformer protection RET650 2.2 IEC 169
Application manual