PhEntity

Crest Factor. Ratio of a waveform's peak value to its RMS value. A clean sine wave reads about 1.4; values that differ indicate waveform distortion that can stress equipment.

Even Total Harmonic Distortion (Even THD). THD computed from only the even harmonics. Even harmonics can indicate asymmetry between the positive and negative halves of a waveform, such as from half-wave rectification or DC offset.

Order of the AC harmonic being measured, expressed as an integer multiple of the fundamental frequency. For example on a 60Hz system an order of 1 is the fundamental (60Hz), 3 is the third harmonic (180Hz), and 5 is the fifth harmonic (300Hz).

Individual Harmonic Distortion (IHD). Magnitude of a single harmonic as a percentage of the fundamental. Used to find which harmonic orders dominate and to check them against per-order limits in standards such as IEEE 519.

K-Factor. Weights harmonic currents by the square of their order to estimate the added heating they cause in transformer windings. The reading can be compared against a transformer's K-rating to check whether it was designed to carry the load.

Line 1 (L1) of an AC electric power system.

Line 2 (L2) of an AC electric power system.

Line 3 (L3) of an AC electric power system.

Between line 1 (L1) and line 2 (L2) of an AC electric power system.

Between line 2 (L2) and line 3 (L3) of an AC electric power system.

Between line 3 (L3) and line 1 (L1) of an AC electric power system.

Average of the L1, L2, and L3 values of a three-phase AC electric power system, or the L1 and L2 values of an AC electric power system with two lines.

Average of the L1-L2, L2-L3, and L3-L1 values of a three-phase AC electric power system.

Odd Total Harmonic Distortion (Odd THD). THD computed from only the odd harmonics. These dominate in typical nonlinear loads such as drives and rectifiers.

Displacement power factor, which accounts for the phase angle between voltage and current but excludes effects of nonlinear waveforms (harmonic distortion).

Distortion power factor, which measures the component of power factor attributable to harmonic distortion in voltage and current waveforms.

Power factor according to the IEC convention defines a positive or negative sign based on the direction of active power flow. Power factor is positive when active power flows into a load. Power factor is negative when active power flows out of a load.

Power factor according to the IEEE convention defines a positive or negative sign based on whether the load is capacitive or inductive. Power factor is positive when the load is capacitive, or when voltage lags behind current. Power factor is negative when the load is inductive, or when current lags behind voltage.

True power factor, which includes effects of harmonic distortion. Power factor is assumed to be true power factor when ElecPfScope is not defined. However, it is recommended to specify a scope for power factor to help avoid misinterpretation of data.

Total Harmonic Distortion (THD). Combined magnitude of all harmonics as a percentage of the fundamental. The primary overall indicator of waveform distortion and power quality.

Telephone Harmonic Form Factor (THFF). Ratio of the frequency weighted components of a waveform to its RMS value. Estimates the potential for interference with nearby communication circuits.