Measuring A Load With Excessive Input Voltage; Attaching The Current Transformer (Ct) - Weidmuller Power Monitor Handbuch

Wiring
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.
• 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.
20
Will cause electric shock or CT breakdown!
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