Multilin 469 Motor Management Relay ... - GE Digital Energy

FIGURE 6–5: Open Delta VT Connection
CHAPTER 6: ACTUAL VALUES
The following phasor diagram presents, in graphic form, the relationship between system
quantities and how they are measured, calculated, and displayed. Note that all angles
shown are negative or lagging angles.
Vca
Phase Rotation
For example, assume a balanced three phase system with a VT Turn Ratio of 35:1, VT
ratings 4200/120 V, and motor running at full load with a power factor of 0.95 (18.2° angle).
When the measured phase to phase voltage is 115 V, the following quantities are displayed
by the relay and EnerVista 469 Setup software:
In the A2 METERING DATA VOLTAGE METERING menu:
VAB: “4025 Volts”
VBC: “4025 Volts”
VCA: “4025 Volts”
AVERAGE LINE VOLTAGE: “4025 Volts”
SYSTEM FREQUENCY: “60.00 Hz”
In the A2 METERING DATA PHASORS menu:
VA PHASOR: “95.8% at 0° Lag”
VB PHASOR: “0.0% at 48° Lag”
VC PHASOR: “95.8% at 300° Lag”
IA PHASOR: “100.0% at 48° Lag”
IB PHASOR: “100.0% at 168° Lag”
IC PHASOR: “100.0% at 288° Lag”
VC =–Vbc
VA=Vab
6–20 469 MOTOR MANAGEMENT RELAY – INSTRUCTION MANUAL
806560A1.CDR
System Voltages:
Vab
Vbc
Vca
Measured Voltages:
Vab = VA (G2 –G1)
–Vbc = VC (H2 – G1)
Calculated Voltage:
Vac = Vab + Vbc
Vbc
Vac
Displayed Voltages:
Va = Vab
Vb =0°
Vc =–Vbc
806556A1.CDR
FIGURE 6–6: Typical Phasor Diagram for Open Delta Connection