Section 9 Secondary system supervision
9.1 Current circuit supervision CCSRDIF (87)
9.1.1 Identification
Function description IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Current circuit supervision CCSRDIF - 87
9.1.2 Functionality
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.
It must be remembered that a blocking of protection functions at an occurrence of open CT
circuit will mean that the situation will remain and extremely high voltages will stress the
secondary circuit.
Current circuit supervision (CCSRDIF, 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 current transformer.
A detection of a difference indicates a fault in the circuit and is used as alarm or to block
protection functions expected to give inadvertent tripping.
9.1.3 Function block
ANSI08000055-1-en.vsd
CCSRDIF (87)
I3P*
BLOCK
IREF
FAIL
ALARM
ANSI08000055 V1 EN
Figure 86: CCSRDIF (87) function block
1MRK 511 287-UUS A Section 9
Secondary system supervision
203
Technical manual
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