Hitachi Relion 670 Series Applications Manual page 199

1MRK506375-UEN Rev. N
Section 11
11.1 Current circuit supervision CCSSPVC
11.1.1 Identification
Function description
Current circuit supervision
11.1.2 Application
Open or short circuited current transformer cores can cause unwanted operation of many protection
functions such as differential and earth-fault current functions. When currents from two independent
two-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 will be
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.
11.1.3 Setting guidelines
The parameters for Current circuit supervision CCSSPVC are set via local HMI or Protection and
Control Manager PCM600.
Common base IED values for primary current (IBase), primary voltage (UBase) and primary power
(SBase) are set in the global base values for settings function GBASVAL.
GlobalBaseSel: To select GBASVAL function for reference of base values.
Operation: For current circuit supervision function Off/On.
Current circuit supervision CCSSPVC compares the residual current from a two-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.
Ip>Block: It is normally set at 150% to block the function during transient conditions.
Railway application RER670
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
INd/I
IEC15000306 V1 EN-US
Section 11
Secondary system supervision
IP14555-1 v5
M14870-1 v5
M12395-13 v9
M12397-17 v9
193