5–6
PQM POWER QUALITY METER – INSTRUCTION MANUAL
A1 METERING
CHAPTER 5: MONITORING
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.
where:
V
av
= average phase voltage = (
V
an
+
V
bn
+
V
cn
) / 3 for
WYE
and
3 WIRE DIRECT
connections
= average line voltage (
V
ab
+
V
bc
+
V
ca
) / 3 for 3 WIRE DELTA/2 VTs connection
V
m
= voltage in a phase (or line) with maximum deviation from
V
av
,
Even though it is possible to achieve unbalance greater than 100% with the
above formula, the PQM will limit unbalance readings to 100%.
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 unbalance 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 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 MINIMUM
: Displays minimum 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. This value is cleared with the
S1 PQM SETUP \ CLEAR DATA \
CLEAR MIN/MAX VOLTAGE VALUES
setpoint.
V
m
V
av
–
V
av
------------------------
100%
×
NOTE
Содержание Multilin PQM
Страница 3: ...Courtesy of NationalSwitchgear com ...
Страница 4: ...Courtesy of NationalSwitchgear com ...
Страница 10: ...TOC VI PQM POWER QUALITY METER INSTRUCTION MANUAL TABLE OF CONTENTS Courtesy of NationalSwitchgear com ...
Страница 348: ...I 10 PQM POWER QUALITY METER INSTRUCTION MANUAL INDEX Courtesy of NationalSwitchgear com ...