GE Multilin T60 Transformer Protection System 6-27
6 ACTUAL VALUES 6.3 METERING
6
Loop impedance is defined as Z##=|Z##| Angle=R##+jX##, in secondary ohms and ## is the loop indication (AB, BC, CA,
AG, BG, and CG respectively).
They are calculated as per the following equations.
Where VA, VB, VC are phase voltage phasors in secondary volts; IA, IB, IC are current phasors in secondary amps, I0 is
the zero sequence current phasors in secondary amps; and IG is the ground current from the parallel line scaled to the
source phase CT in secondary amps.
Z0/Z1 is the zero sequence impedance to positive sequence impedance ratio, and Z0M/Z1 is mutual zero sequence imped-
ance to positive sequence impedance ratio, both are settings taken from the first enabled ground distance zone (count from
zone 1 to zone 5).
ZAG, ZBG, ZCG are calculated only if at least one ground distance zone is enabled; otherwise all the metering quantities for
ground distance impedance (ZAG, ZBG, and ZCG) are reset to zero, including magnitude and angle. Note that VTs of the
distance source must be connected in Wye if the ground distance element is enabled.
MESSAGE
CA LOOP IMPEDANCE
ZCA: 0.00 Ohms
MESSAGE
CA LOOP IMPEDANCE
ANGLE: 0.00 DEG
MESSAGE
AG LOOP RESISTANCE
RAG: 0.00 Ohms
MESSAGE
AG LOOP REACTANCE
XAG: 0.00 Ohms
MESSAGE
AG LOOP IMPEDANCE
ZAG: 0.00 Ohms
MESSAGE
AG LOOP IMPEDANCE
ANGLE: 0.00 DEG
MESSAGE
BG LOOP RESISTANCE
RBG: 0.00 Ohms
MESSAGE
BG LOOP REACTANCE
XBG: 0.00 Ohms
MESSAGE
BG LOOP IMPEDANCE
ZBG: 0.00 Ohms
MESSAGE
BG LOOP IMPEDANCE
ANGLE: 0.00 DEG
MESSAGE
CG LOOP RESISTANCE
RCG: 0.00 Ohms
MESSAGE
CG LOOP REACTANCE
XCG: 0.00 Ohms
MESSAGE
CG LOOP IMPEDANCE
ZCG: 0.00 Ohms
MESSAGE
CG LOOP IMPEDANCE
ANGLE: 0.00 DEG
ZAB
VA VB–
IA IB–
----------------------
ZBC =
VB VC–
IB IC–
-----------------------
ZCA
VC VA–
IC IA–
-----------------------
==
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