Current Circuit Supervision (87) - ABB REC670 Applications Manual

1MRK 511 401-UUS A
Section 13
13.1
13.1.1
13.1.2
Bay control REC670 2.2 ANSI
Application manual
Secondary system supervision

Current circuit supervision (87)

Identification
Function description
Current circuit supervision
Application
Open or short circuited current transformer cores can cause unwanted operation of
many protection functions such as differential, ground-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 (87) 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.
Secondary system supervision
IEC 61850 IEC 60617
identification identification
CCSSPVC -
Section 13
IP14555-1 v5
M14870-1 v5
ANSI/IEEE C37.2
device number
87
M12395-13 v9
293