User Documentation
Wiring
20 1435710000/01/05.13
6.2.2 Measuring a load with excessive input voltage
• A voltage transformer (VT) is needed to measure a load with excessive input voltage.
• Use a VT whose secondary voltage rating is 110 V.
• Grounding the secondary side of the VT and CT is not necessary with a low-voltage circuit.
6.3 Attaching the Current Transformer (CT)
DANGER!
• Never open the secondary circuit of CT when current is applied to the load.
• Never remove the terminal block when current is applied to the load.
Will cause electric shock or CT breakdown!
• Use a CT with a secondary side current of 5 A or 1 A, the rated burden 0.5 VA or more.
• One CT is needed for one unit when measuring 1P2W (2 CTs for 2 circuits, 3 CTs for 3 circuits). Two CTs
are needed when measuring 1P3W/3P3W. Three CTs are needed when measuring 3P4W.
• Use the appropriate or it might cause a breakdown, burnout or electric shock.
• When connecting the CT, connect the secondary side to the terminal of the main unit first,then wire the
primary side to a load electric wire. Not keeping to this sequence may cause an electric shock or CT
breakdown.
• The CT has polarity. Wire correctly in accordance with the K and L marks. Wiring in the wrong direction
will result in incorrect measurement.
• If harmonic or waveform distortion occurs, measurements may be inaccurate. Please check the current
system before adopting it.
• Separate the wiring (strong electric part) of the measured voltage input terminal (operating power supply
terminal) from the CT cable. It may not satisfy the accuracy requirements due to noise.