5.5.2 PF, Leading or Lagging?
The terms leading and lagging power factor refer to the relative phase shift between the
current and voltage waveforms. The current leads the voltage in a capacitive load while the
current lags the voltage in an inductive load. When calculating power factor using a 2105, there
is no way of determining whether the voltage waveform is leading or lagging the current. An
oscilloscope must be used to determine leading or lagging. Fortunately, most every load has a
lagging power factor.
If the load has a transformer, fan, or motor, it is safe to assume lagging power factors and an
oscilloscope is not required.
5.5.3 Accuracies
The accuracies of these calculations are the sums of the accuracies of the voltage, current and
power measurements. For the 2105, the specified accuracies of section 3-3 should be summed
to find the total uncertainty.
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