ABB RELION RET670 Applications Manual page 681

1MRK 504 163-UUS A
Transformer protection RET670 2.2 ANSI
Application manual
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
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=
ANSI13000279 V1 EN-US
V is defined as phase to neutral or phase to phase voltage dependent of the
SetPrim
selected ConTypeMain and ConTypePilot. If ConTypeMain and ConTypePilot are set to
Ph-N than the function performs internally the rescaling of V
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.
Secondary system supervision
V
SetPrim
⋅100
V
Base
Section 14
is
SetPrim
(Equation 503)
.
SetPrim
675