3-9
Power factor output is also commonly
available as an additional feature on single
and multi-phase watt transducers. In this
case, the transducer is connected in the same
manner as a conventional multi-phase watt
transducer (refer to figure 9).
Regardless of the type of transducer or
meter employed, the 1040C has a provision
for direct calibration of power factor. As
stated earlier in this document, the power
factor in a circuit is equal to the cosine of the
phase angle between the voltage and the
current. With this in mind, any power factor
can be simulated by adjusting the phase
relationship between the voltage and current,
which can be accomplished quite easily with
the 1040C. Two methods can be used:
• The required phase angle can be
entered directly via the keypad, as
described in the section on phase
angle calibration;
• The power factor can be entered
directly, by first pressing the "Power
Factor" key, then using the adjust
knob to vary the displayed power
factor. This method allows entry of
lead or lag power factor values
without having to first calculate the
corresponding phase angle.
Calibration of the transducer should be
performed according to the instrument
manufacturer's recom-mendations.
Typical applications of power factor
meters for multi-phase systems involve circuit
connections which are similar, if not identical
to those employed by multi-phase phase angle
transducers. Generally, the current is
measured in one phase, and a comparison is
made between it and the net voltage between
the remaining two phases. Substituting a
meter for the transducers shown in figure 11
will give a good indication of the type of
connections necessary for typical applications
and calibration.
For more detailed instructions on
operating the 1040C for calibration of power
factor, refer to section 2.5.1 of the operation
manual.
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