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IM WT310-02EN
Making Preparations for Measurements
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App
Index
CAUTION
The thick lines on the wiring diagrams are the parts where the current flows. Use wires that
are suitable for the current levels.
Note
• Make sure that you have the polarities correct when you make connections. If the polarity is reversed,
the polarity of the measurement current will be reversed, and you will not be able to make correct
measurements. Be especially careful when connecting clamp-type current sensors to the circuit under
measurement, because it is easy to reverse the connection.
• Note that the frequency and phase characteristics of the VT or CT affect the measured data.
• For safety reasons, the common terminals (+/–) of the secondary side of the VT and CT are grounded in
the wiring diagrams in this section. However, the necessity of grounding and the grounding location (ground
near the VT or CT or ground near the power meter) vary depending on the item under measurement.
• To measure the apparent power and power factor more accurately on an unbalanced three-phase circuit,
we recommend that you use the three-voltage, three-current method (3V3A).
When using the Yokogawa 751552 Clamp-on Probe, use the 758917 Measurement Lead and the
758921 Fork Terminal Adapter Set (optional accessory).
758917
751552
758921
WT310/WT310HC
WT332/WT333
Current input
terminals
Current input
terminals
2.11 Wiring the Circuit under Measurement When Using a Voltage or Current Transformer