GE Power Quality Meter Series, Инструкция по эксплуатации

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4-20 PQM Power Quality Meter GE Power Management
4.3 S2 SYSTEM SETUP 4 PROGRAMMING
4
• PHASE CT PRIMARY: Enter the primary current rating of the phase current transformers. All three phase
CTs must have the same rating. For example, if 500:5 CTs are used, the
PHASE CT PRIMARY value is
entered as 500 . The PHASE CT PRIMARY factory default is OFF . While set to OFF , the PQM is forced to an
alarm state as a safety precaution until a valid CT value is entered. Ensure that the CT is connected to the
correct 1 A or 5 A terminals to match the CT secondary.
• NEUTRAL CURRENT SENSING: Neutral current sensing can be accomplished by using a separate exter-
nal CT connection or by calculations. Select
SEPARATE CT when using an external CT. If CALCULATED is
selected, the PQM calculates the neutral current using the vector sum of I
a
+ I
b
+ I
c
= I
n
. If a residual con-
nection is required using the PQM internal CT, the neutral CT primary must be the same as the phase CT
primary to ensure correct readings.
• NEUTRAL CT PRIMARY: This message is visible only if the NEUTRAL CURRENT SENSING setpoint is set to
SEPARATE CT . Enter the CT primary current. For example, if a 50:5 CT is installed for neutral sensing enter
50 . One amp CTs can also be used for neutral sensing.
• VT WIRING: Enter the VT connection of the system in this setpoint. The three possible selections are Wye,
Delta and Single Phase.
If the system to be measured is a Wye connection, the selections are 4 WIRE WYE DIRECT , 4 WIRE WYE (3 VTs) ,
and 4 WIRE WYE (2 VTs) . The 4 WIRE WYE DIRECT value is used for systems that are 600 V or less and directly
connected to the PQM. The VT NOMINAL SECONDARY VOLTAGE setpoint is replaced by NOMINAL DIRECT INPUT
VOLTAGE . With external VTs (depending upon how many external VTs are used) 4 WIRE WYE (3 VTs) or 4 WIRE
WYE (2 VTs) must be selected. Note that when using the 4 WIRE WYE (2 VTs) value, only two voltages are
measured; the third voltage is calculated on the assumption that V
an
+ V
bn
+ V
cn
=
0. This assumption is
valid only for balanced system voltages.
If the system to be measured is a Delta connection, the values are 3 WIRE DIRECT and 3 WIRE DELTA (2 VTs) .
The 3 WIRE DIRECT value should be used for systems that are 600 V or less and directly connected to the
PQM. With external VTs, 3 WIRE DELTA (2 VTs) must be selected.
The PQM accepts input voltages from 0 to 600 V AC between any two of the voltage terminals (V
1
, V
2
, V
3
,
and V
n
). These inputs can be directly connected or supplied via external VTs. External VTs are required for
input voltages greater than 600 V AC (line-to-line). When measuring line-to-line quantities using inputs V
1
,
V
2
and V
3
, ensure that the voltage common input V
n
is grounded. This input is used as a reference for
measuring the voltage inputs.
All connections to the PQM voltage inputs should be connected using HRC fuses rated at 2 amps
to ensure adequate interrupting capacity.
• VT RATIO: Enter the voltage transformer ratio. All three voltage inputs must be of the same rating. For
example, if 4200:120 VTs are used, the
VT RATIO should be 4200 / 120 = 35.0:1. This setpoint is not visible
if VT WIRING is set to 3 WIRE DIRECT , 4 WIRE DIRECT , or SINGLE PHASE DIRECT .
• VT NOMINAL SECONDARY: Enter the nominal secondary of the VTs. If the voltage inputs are directly
connected, enter the nominal system voltage that will be applied to the PQM. This setpoint is not visible if
the
VT WIRING is set to 3 WIRE DIRECT , 4 WIRE DIRECT , or SINGLE PHASE DIRECT . This value is used to scale an
analog output that is assigned to display voltage as a percentage of nominal.
• NOMINAL DIRECT INPUT VOLTAGE: This setpoint is displayed only if VT WIRING is selected as a direct
connection. The nominal direct input voltage must be entered in this message. This value will be used to
scale an analog output that is assigned to display voltage as a percentage of nominal.
• NOMINAL SYSTEM FREQUENCY: Enter the nominal system frequency. The PQM measures frequency
from the
V
an
voltage and adjusts its internal sampling to best fit the measured frequency. If the V
an
input is
unavailable, the PQM will assume the frequency entered here.
NOTE