Secondary System Supervision; Current Circuit Supervision (87); Identification; Application - Hitachi Relion 670 Series Applications Manual

1MRK511407-UUS Rev. N
Section 13
13.1

Current circuit supervision (87)

13.1.1

Identification

Function description
Current circuit supervision
13.1.2

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.
13.1.3

Setting guidelines

GlobalBaseSel: Selects the global base value group used by the function to define IBase, VBase and
SBase. Note that this function will only use IBase .
Current circuit supervision CCSSPVC (87) 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.
IMinOp: It must be set as a minimum to twice the residual current in the supervised CT circuits under
normal service conditions and rated primary current.
Pickup_Block: It is normally set at 150% to block the function during transient conditions.
The FAIL output is connected to the blocking input of the protection function to be blocked at faulty CT
secondary circuits.
Phasor measurement unit RES670
Application manual

Secondary system supervision

IEC 61850
identification
CCSSPVC
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.
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IEC 60617 ANSI/IEEE C37.2
identification device number
- 87
Section 13
Secondary system supervision
IP14555-1 v5
M14870-1 v5
M12395-13 v9
M12397-17 v9
187