The connection type for the main and the pilot fuse groups must be
consistent.
The settings Vdif Main block, Vdif Pilot alarm and VSealIn are in percentage of the
base voltage, VBase. Set VBase to the primary rated phase-to-phase voltage of the
potential voltage transformer. VBase
is available in the Global Base Value groups; the
particular Global Base Value group, that is used by VDSPVC (60), is set by the setting
parameter GlobalBaseSel.
The settings Vdif Main block and Vdif Pilot alarm should be set low (approximately
30% of VBase) so that they are sensitive to the fault on the voltage measurement
circuit, since the voltage on both sides are equal in the healthy condition. If V
SetPrim
is
the desired pick up primary phase-to-phase voltage of measured fuse group, the setting
of Vdif Main block and Vdif Pilot alarm will be given according to equation
503.
Vdif Main block or Vdif Pilot alarm=
SetPrim
Base
V
V
⋅100
ANSI13000279 V1 EN-US (Equation 503)
V
SetPrim
is defined as phase to neutral or phase to phase voltage dependent of the
selected ConT
ypeMain
and ConTypePilot. If ConTypeMain and ConTypePilot are set to
Ph-N than the function performs internally the rescaling of V
SetPrim
.
When SealIn is set to On and the fuse failure has last for more than 5 seconds, the
blocked protection functions will remain blocked until normal voltage conditions are
restored above the VSealIn setting. The fuse failure outputs are deactivated when the
normal voltage conditions are restored.
1MRK 504 163-UUS A Section 14
Secondary system supervision
Transformer protection RET670 2.2 ANSI 675
Application manual
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