Principle Of Operation; Signal Plausibility Check; Vt And Ct Configuration - Hitachi Relion 650 Series Technical Manual

1MRK 511 557-UEN Rev. A
14.5.7

Principle of operation

ANSGPROC receives voltage and current signals from SMAI (pre-processing) function blocks. From
these signals, it extracts properties that are required for controlled switching (point-on-wave
switching) and operations monitoring, and publishes them together with other relevant data.
14.5.7.1

Signal plausibility check

Both voltage and current signals are continuously validated to be healthy that is, suitable as
reference for controlled switching. As soon as the RMS magnitude of voltage or current samples
received by the function (through U3P or I3P) crosses a pre-defined threshold value or dead value
(Udead or IDead), the source is considered healthy. If the RMS magnitude of the signal is less than
the threshold, the signal cannot be used as a reference. The information is published on the
VOLREFOK and CURREFOK outputs, wherein a value of TRUE (1) indicates healthy signal.
For a three-phase signal, the health of each phase is checked individually. Only if all phases are
found healthy, the entire reference signal is declared healthy.
Table 355: Dead value settings
Setting name
UDead
IDead
GlobalBaseSel
14.5.7.2

VT and CT configuration

The source voltage signals can be provided from single-phase or three-phase VTs, which measure
either phase-to-ground or phase-to-phase voltages. The actual VT configuration is selected using the
settings detailed in
Technical Manual
Description
Threshold level for input source voltage signal in percent of UBase. If the voltage RMS is less
than this threshold level, source voltage cannot be used as reference.
Threshold level for input current signal in percent of IBase. If the current RMS is less than
this threshold level, load current cannot be used as reference.
Selection of GBASVAL function instance from which UBase and IBase are taken.
ANSGPROC expects that UBase and IBase in GBASVAL (selected by
GlobalBaseSel) are set as rated phase-to-ground voltage and maximum steady-
state current into the load, respectively. For controlled switching of transformers,
transmission lines, or cables, the steady-state current shall be given as the nominal
charging current, with no further load connected.
Table 356.
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Section 14
Basic IED functions
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