secondary circuit. In the "Non-latched" mode, the ALARM output functions normally,
that is, it resets as soon as the fault is cleared.
6.4.5 Measuring modes
The function operates on two alternative measurement modes, DFT and Peak-to-
Peak. The measurement mode is selected using the
Measurement mode
setting.
6.4.6 Application
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 operation principle of HZCCxSPVC is similar to the high-
impedance differential protection function HIxPDIF. However, the current setting of
HZCCxSPVC is set to be much more sensitive than HIxPDIF and it operates with a
higher time delay. A typical example of the HZCCxSPVC
Start value
setting is 0.1 pu
with an
Alarm delay time
of 3 s or more.
As the current setting of HZCCxSPVC is more sensitive than the actual differential
stage, it can start internally under the through-fault conditions; however, a
sufficient time delay prevents false alarm. If the bus wire is broken, differential
current arises depending on the load of the feeder with the broken bus wire.
1MRS757644 H
Supervision functions
620 series
Technical Manual
893
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