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3-18
IM 760301-01E
Note
•
After wiring, the wiring system must be selected. See section 4.1, “Selecting the Wiring
System.”
•
The thick lines on the wiring diagrams are the sections where the current flows. Use
appropriate wires that are suitable for the current.
•
To measure the apparent power and power factor more accurately on an unbalanced three-
phase circuit, it is recommended that a three-phase, three-wire system (three-voltage, three-
current system) [3P3W (3V3A)] be used to make the measurement.
•
The current sensor input transformation function can be used to transform the input signal to
data that correspond to direct measurements. For the setup procedure, see section 4.4,
“Setting the Measurement Range When Using the Current Sensor.”
•
Note that the frequency and phase characteristics of the current sensor affect the measured
data.
•
Make sure you have the polarities correct when making the connections. Otherwise, the
polarity of the measurement current will be reversed and correct measurements cannot be
made. Be especially careful when connecting the clamp type current sensor, because it is
easy to reverse the connection.
•
To minimize error when using a shunt-type current sensor, note the following points when
connecting the external sensor cable.
•
Connect the shielded wire of the external sensor cable to the L side of the shunt output
terminal (OUT).
•
Minimize the area created between the wires connecting the current sensor to the external
sensor cable. The effects due to the line of magnetic force (caused by the measurement
current) and noise that enter this area of space can be reduced.
Shunt-type
current sensor
I
±
OUT H
OUT L
Shielded wire
External sensor cable
(B9284LK, sold separately)
WT3000
Area of space created by the connection wires
•
For a shunt-type current sensor, connect it to the power earth ground side as shown in the
figure below. If you have to connect the sensor to the non-earth side, use a wire that is thicker
than AWG18 (conductive cross-sectional area of approx. 1 mm
2
) between the sensor and the
instrument to reduce the effects of common mode voltage. Take safety and error reduction
into consideration when constructing an external sensor cable.
LOAD
Shunt-type current sensor
V
±
External current sensor
Input connector
Voltage input terminal
Power meter
•
When the circuit under measurement is not grounded and the signal is high in frequency or
large in power, the effects of the inductance of the connection cable for the shunt-type current
sensor become large. In this case, use an isolation sensor (CT, DC-CT, or clamp).
Clamp-type current sensor
External current sensor
Input connector
LOAD
V
±
Voltage input terminal
Power meter
3.10 Wiring the Circuit under Measurement When Using the Current Sensor
Содержание wt3000
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