GE 845 Instruction Manual page 506

CHAPTER 6: METERING
METERING
The relay measures all RMS (root mean square) currents and voltages, frequency, and all
auxiliary analog inputs. Other values like neutral current, phasor symmetrical
components, power factor, power (real, reactive, apparent), are derived. A majority of these
quantities are recalculated every protection pass and perform protection and monitoring
functions. Displayed metered quantities are updated approximately three (3) times a
second for readability. All phasors and symmetrical components are referenced to the A-N
voltage phasor for wye-connected VTs; to the A-B voltage phasor for delta-connected VTs;
or to the phase A current phasor when no voltage signals are present.
Figure 6-2: An example of the Metering\Summary submenu
All the measured values can be viewed on the front panel display or monitored by remote
devices through the communication system. An example of the HMI display showing
actual currents is shown here.
The measured values can also be displayed in the PC (EnerVista 8 Series) program. The
same example of actual currents displayed in the EnerVista 8 Series program is shown as
follows.
6–2 845 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL