GE D90 Plus Instruction Manual page 573

CHAPTER 11: METERING
PLUS
D90 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
The following voltages and currents are measured for wye-connected instrument
transformers in the ACB phase rotation:
The following voltages and currents are measured for delta-connected instrument
transformers in the ABC phase rotation. The zero-sequence voltage (V_0) is not measurable
under the delta connection of instrument transformers and is defaulted to zero.
The following voltages and currents are measured for delta-connected instrument
transformers in the ACB phase rotation. The zero-sequence voltage (V_0) is not measurable
under the delta connection of instrument transformers and is defaulted to zero.
In these equations, a represents phase rotation operator that rotates a phasor vector
forward by 120° (a = 1∠120°).
As an example, consider a wye connected VT with the following system voltages (in
secondary volts): V = 13.9 V∠0°, V
AG
313°, V = 138.3 V∠–97°, and V
BC
voltages are phase-referenced to V
is important to remember that displayed values are always referenced as to the voltage
specified by the Frequency and Phase Reference
As another example, consider a delta connected VT with the following system voltages (in
secondary volts): V = 84.9 V∠0°, V
AB
simplicity, the power system voltages are phase-referenced to V
= 76.2 V∠–125°, V
BG CG
= 85.4 V∠–241°. For simplicity, the power system
CA
. However, any value can be chosen as a reference. It
AG
setting.
= 138.3 V∠–144°, and V
BC
METERED VALUES
Eq. 57
Eq. 58
Eq. 59
Eq. 60
Eq. 61
Eq. 62
Eq. 63
= 79.7 V∠–250°, V = 84.9 V∠–
AB
Eq. 64
Eq. 65
Eq. 66
= 85.4 V∠–288°. For
CA
. However, any value
AB
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