ABB RELION REX640 Technical Manual page 1319

1MRS759142 F
6.3 Current transformer supervision for high-
impedance protection scheme HZCCxSPVC (ANSI
CCM_A, CCM_B, CCM_C)
6.3.1 Identification
Function description
Current transformer supervision for
high-impedance protection scheme
for phase A
Current transformer supervision for
high-impedance protection scheme
for phase B
Current transformer supervision for
high-impedance protection scheme
for phase C
6.3.2 Function block
Figure 751: Function block
6.3.3 Functionality
The current transformer supervision for high-impedance protection scheme
function HZCCxSPVC is a dedicated phase-segregated supervision function to be
used along with the high-impedance differential protection for detecting the broken
CT secondary wires. The differential current is taken as an input for the protection
relay. During normal CT condition, the value of the differential current is zero.
However, when the CT is broken, the secondary differential current starts flowing
and it is used for generating alarms.
To avoid maloperation, HZCCxSPVC should have a sensitive setting, compared to
the high-impedance differential protection. The function is likely to start under
through-fault conditions. However, by incorporating a high time delay (3 s or more),
the downstream protection clears the fault before an alarm is generated.
HZCCxSPVC generates an alarm when the differential current exceeds the set limit.
The function operates within the DT characteristic.
HZCCxSPVC contains a blocking functionality. It is possible to block the function
output, Timer or the whole function.
REX640
Technical Manual
IEC 61850 IEC 60617
identification identification
HZCCASPVC MCS I_A
HZCCBSPVC MCS I_B
HZCCCSPVC MCS I_C
Supervision functions
ANSI/IEEE C37.2
device number
CCM_A
CCM_B
CCM_C
1319