4
Phase Angle
Calibration of phase angle meters or
transducers for single phase operation
requires use of both the voltage and current
outputs of the 1040C. The representative
circuit connection diagrams for these types of
devices are the same as for the ac power
meters and transducers, given in figure 5.
Typical connections for calibration are also
the same as for ac power meters and
transducers, and are given in figure 6. For
calibration, the 1040C voltage output leads
are connected to the voltage terminals of the
meter or transducer, and the 1040C current
output leads are connected to the current
input terminals of the meter or transducer
(figure 6a and 6c). If the meter or transducer
uses an external current transformer, one of
the current output leads of the 1040C should
be passed through the center of the current
transformer, and then shorted to the other
lead. If the meter or transducer uses an
external potential transformer, then likewise
it must be inserted between the 1040C
voltage output leads and the input voltage
leads of the unit under test. Refer to figures
6b and 6d for these two types of connections.
The 1040C should first be configured to
operate in the ac power mode, as described in
paragraph 2.5.6, and the appropriate voltage
and current values should be selected. After
the outputs have been enabled and the phase
angle meter or transducer under test has been
observed to be indicating zero, press the
"Phase" button. This will allow shifting of
the relative phase between the voltage and
the current outputs. The desired phase angle
can now be entered directly, via the keypad,
and followed by the appropriate units
(degrees). A negative value for phase angle
corresponds to the output current lagging the
output voltage. After entering the value for
phase angle, the operator may adjust the
value by using the control knob, or by using
the "Up" or "Down" keys. For more
complete instructions on operation of the
1040C for phase angle calibrations, refer to
section 2.5.1 of the operation manual.
Power Factor
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.
For an illustration of the relationship
between phase angle and power factor in the
1040C, refer to figure 12.
In order to accomplish power factor
indication, some transducer manufacturers
recommend using one of their phase angle
transducers and performing a mathematical
conversion on the output signal. This can be
done manually, using conversion tables
supplied by the manufacturer, or
automatically, using a meter having cosine
scaling. Typical transducer application
circuit connections and calibration setup
connections are usually the same as those for
a phase angle, watt, or var transducer, as
shown in figures 5 and 6. Calibration can be
performed using the connections in figure 6
and one of the methods outlined above, and
in accordance with the transducer
manufacturers recommendations.
Power factor output is also commonly
available as an additional feature on single
