Distance Measuring Units (Dmu) - GE MLP1000 Manual

three ground-phase voltages from the analog/digital converter . These samples are
corrected according to the gains applied during the extension period.
The fundamental component phasors for the for the three currents and phase
voltages are obtained (in rectangular coordinates) from the instantaneous samples and
previous samples using a phasor identification algorithm based on the "minimum squares
algorithm".

4.3 DISTANCE MEASURING UNITS (DMU)

The relay has 18 distance measuring units, however the zone 1 and zone 2 units
are not activated simultaneously:
Zone 1: AG, BG, CG, AB, BC, CA.
Zone 2: AG, BG, CG, AB, BC, CA.
Zone 3: AG, BG, CG, AB, BC, CA.
The measuring units operating characteristics are:
Phase-ground faults:
Reactance or MHO variable (switchable) in zones land 2, MHO variable in Zone
3 that supervises. reactance operations, when selected.
Phase-phase faults:
MHO variable in the three zones.
The operation and polarization quantities used in the reactance units for
ground-phase faults, in zones 1 and 2 are:
Fault
The quantities used in the mho units for phase-ground faults, in zones l, 2 and 3
are:
Fault
The quantities used in the mho units for faults between phases, in all zones
are:
Fault
Where: I'Øx Zr = (IØ - I0) x Zr/Θ1 + K0 x I0 x Zr/Θ0
Zr: Set impedance reach.
Xr: Relay reactive angle of maximum reach.
GEK-98846A
Quantity Operation
ØG I'Øx Zr - Vøn
Quantity Operation
ØG I'Øx Zr - Vøn
Quantity Operation
ØØ IØØx Zr
Polarization Qty.
IØ2 x Xr
Polarization Qty.
VØ1m
Polarization Qty.
VØØ1m
21