Amprobe ACD-45PQ Power-Quality-Clamp - Manual (Page 12)

6
In ACA function, activating the Hz function during significant measurements
can get the most appropriate trigger level to avoid electrical noises in
most cases. Activating the Hz function at AC 40.00A range (before making
significant measurements) can get the lowest trigger level (highest sensitivity).
HOLD Mode
When any function is auto-selected or manual-selected, press HOLD button
momentarily toggles to Hold mode. The annunciator “ ” turns on. Hold
mode freezes the display for later viewing.
Notes on Displacement Power Factor & Total Power Factor
• Introduction: Power is the rate of change of energy with respect to time
(in terms of voltage V and current A). Instantaneous (real) power w = vi
where v is the instantaneous voltage and i the instantaneous current.
The average (real) power is the mean of vi and is given by:
W = ω/2π∫vi dt , over the interval from 0 to 2π/ω
• Displacement Power Factor (more traditional): Assuming V and A are
pure sinusoidal waveforms without harmonics (as in most traditional
cases), that is, v = V sinωt and i = I sin (ωt -θ), the expression can be
simplified to:
W = 1/2 x V x I x Cosθ where V and I are the peak values, θ is the
displacement power factor angle, and Cosθ is the displacement power
factor. Using RMS values, it is written as:
W = Vrms x Arms x Cosθ
Practically, in such cases without harmonics, θ is also called the phase-
shift angle of the current A to the voltage V. An inductive circuit is said
to have a lagging power factor since current A lags voltage V (phase-
shift angle θ and thus Sinθ are both “+”), and a capacitive circuit is said
to have a leading power factor since current A leads voltage V (phase-
shift angle θ and thus Sinθ are both “-”).
• Total Power Factor (encountering harmonics): When encountering
distorted waveforms with the presence of harmonics, however, the
simplified power expression should not be used since substituting the
above mentioned pure sinusoidal V and A functions cannot fulfill the
actual conditions. Cosine of phase-shift angle (Cosθ), or the displacement