GE Power Quality Meter Series Instruction Manual page 119

5 MONITORING
Van, Vbn, Vcn, VOLTAGE: Displays each phase voltage corresponding to the A, B, and C voltage inputs. This
voltage will be measured correctly only if the VT RATIO, VT NOMINAL SECONDARY, and VOLTAGE WIRING setpoint
values match the installed VTs. If the displayed voltage does not match the actual voltage, check the setpoints
and wiring. This message appears only if the VT WIRING is configured for a wye input.
Iavg/Vavg: Displays the average of the three phase currents/voltages. This value is not visible if the VT WIRING
setpoint is set to SINGLE PHASE DIRECT. L-N is displayed when VT WIRING is set to 4 WIRE WYE (3 VTs), 4 WIRE WYE
DIRECT, 4 WIRE WYE (2 VTs), or 3 WIRE DIRECT and L-L is displayed when VT WIRING is set to 3 WIRE DELTA (2 VTs).
Vab, Vbc, Vca, VOLTAGE: Displays each line voltage corresponding to the A, B, and C voltage inputs. The
measured voltage is correct only if the VT RATIO, VT NOMINAL SECONDARY, and VOLTAGE WIRING setpoints match
the installed VTs. If the displayed voltage does not match the actual voltage, check the setpoints and wiring.
AVERAGE LINE VOLTAGE: Displays the average of the three line voltages. This value is not visible if the VT
WIRING setpoint is set to SINGLE PHASE DIRECT.
VOLTAGE UNBALANCE: Displays the percentage voltage unbalance. Voltage unbalance is calculated as
shown below. If the VOLTAGE WIRING is configured for a WYE input, voltage unbalance is calculated using phase
quantities. If the VT WIRING is configured as a DELTA input, voltage unbalance is calculated using line voltages.
V V
–
m av ×
100%
------------------------- -
V
av
where: V = average phase voltage = ( V
av
= average line voltage ( V
V = voltage in a phase (or line) with maximum deviation from V
m
Even though it is possible to achieve unbalance greater than 100% with the above formula, the PQM
will limit unbalance readings to 100%.
NOTE
If the average voltage is below 10% of VT RATIO × VT NOMINAL SECONDARY VOLTAGE for 3 WIRE DELTA/2 VTs, 4 WIRE
WYE/3 VTs, and 4 WIRE WYE/2 VTs connections, or below 10% of VT RATIO × NOMINAL DIRECT INPUT VOLTAGE for 4
WIRE WYE/DIRECT and 3 WIRE DIRECT connections, the unbalance reading is forced to 0%. This is implemented to
avoid nuisance alarms when the system is lightly loaded. If the simulation voltages are being used, the unbal-
ance is never forced to 0%.
Van, Vbn, Vcn MINIMUM: Displays the minimum phase voltage magnitudes and the time and date of their
occurrence. This information is stored in non-volatile memory and is retained during loss of control power. The
S1 PQM SETUP \ CLEAR DATA \ CLEAR MIN/MAX VOLTAGE VALUES setpoint clears these values.
Vab, Vbc, Vca MINIMUM: Displays the minimum line voltage magnitudes and the time and date of their occur-
rence. This information is stored in non-volatile memory and is retained during loss of control power. The S1
PQM SETUP \ CLEAR DATA \ CLEAR MIN/MAX VOLTAGE VALUES setpoint clears these values.
V U/B MINIMUM: Displays minimum voltage unbalance and the time and date of its measurement. This infor-
mation is stored in non-volatile memory and is retained during loss of control power. This value is cleared with
the S1 PQM SETUP \ CLEAR DATA \ CLEAR MIN/MAX VOLTAGE VALUES setpoint.
Van, Vbn, Vcn MAXIMUM: Displays the maximum phase voltage magnitudes and the time and date of their
occurrence. This information is stored in non-volatile memory and is retained during loss of control power. The
S1 PQM SETUP \ CLEAR DATA \ CLEAR MIN/MAX VOLTAGE VALUES setpoint clears these values.
Vab, Vbc, Vca MAXIMUM: Displays the maximum line voltage magnitudes and the time and date of their
occurrence. This information is stored in non-volatile memory and is retained during loss of control power. The
S1 PQM SETUP \ CLEAR DATA \ CLEAR MIN/MAX VOLTAGE VALUES setpoint clears these values.
V U/B MAXIMUM: Displays the maximum voltage unbalance and the time and date of its measurement. This
information is stored in non-volatile memory and is retained during loss of control power. The value is cleared
with the S1 PQM SETUP \ CLEAR DATA \ CLEAR MIN/MAX VOLTAGE VALUES setpoint.
GE Power Management
) / 3 for WYE and 3 WIRE DIRECT connections
+ V + V
an bn cn
+ V + V ) / 3 for 3 WIRE DELTA/2 VTs connection
ab bc ca
PQM Power Quality Meter
5.2 A1 METERING
,
av
5
5-5