ABB Relion 670 series - Page 742

internal signal FuseFailDetDVDI at the level high, then the signal FuseFailDetDVDI will remain high
as long as the voltage of three phases are lower then the setting VPPU.
In addition to fuse failure detection, two internal signals DeltaV and DeltaI are also generated by
the delta current and delta voltage DVDI detection algorithm. The internal signals DelatV and
DeltaI are activated when a sudden change of voltage, or respectively current, is detected. The
detection of the sudden change is based on a sample analysis algorithm. In particular DelatV is
activated if at least three consecutive voltage samples are higher then the setting DVPU . In a
similar way DelatI is activated if at least three consecutive current samples are higher then the
setting
DIPU .When DeltaV or DeltaI are active, the output signals PU_DV_A, PU_DV_B, PU_DV_C
and respectively PU_DI_A, PU_DI_B, PU_DI_C, based on a sudden change of voltage or current
detection, are activated with a 20 ms time off delay. The common pickup output signals PU_DV or
PU_DI are activated with a 60 ms time off delay, if any sudden change of voltage or current is
detected.
The delta function (except the sudden change of voltage and current detection) is
deactivated by setting the parameter
OpDVDI to Disabled .
Section 13 1MRK 502 066-UUS B
Secondary system supervision
736
Technical manual