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Operation
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that the (+) and (-) terminals on the CT correspond directly to
the (+) and (-) terminals of the 918B current input.
3.
Clamp the CT around the wire carrying the current to be
measured, making certain that the jaws close completely. Note
the (+) and (-) symbols, indicating the phase relationship
between the CT input and the CT output.
4.
Although not critical for volt-amp indication, this will be of
particular importance for measurement of parameters involving
phase angle, such as power factor, watts, and vars, which will be
covered in subsequent sections of this manual.
5.
Plug the supplied test probes into the voltage input terminals,
with the red wire connected to the (+) terminal and the black
wire connected to the (-) terminal.
6.
Connect the black lead to the circuit neutral or ground, or the
point to be used as the reference for the measurement.
7.
Connect the red test lead to the voltage to be measured. The
value displayed will be the product of the rms voltage and the
rms current in the circuit.
Operating Ranges
For voltage inputs, the 918B has four different operating ranges. For
current inputs, the 918B has three different operating ranges. De-
pending on the levels of voltage and current applied to the inputs,
the instrument may automatically switch between ranges. This range
switching is internal, and may or may not be evident in the display.
Automatic range switching can be defeated, using range hold. Refer
to section 3.1, "Automatic and Manual Range Selection", for a de-
scription of the internal ranges, the display ranges, auto ranging
operation, and range hold operation.
Flashing Display – Input Low
For the VA mode, minimum values of voltage and current must be
present at the inputs to maintain accuracy. The 918B display will