User Manual

The menu system

The reference v

alue can be either the fundamental reading or the RMS reading.

The default reference is the fundamental value.

Total Harmonic Distortion. THD is a measure of the distortion of a waveform.

Under the V and A measurement menus is the ability to set the following

parameters:

Harmonic Reference. Fundamental or RMS (default Fundamental).

Harmonic Sequence. Odd and Even or Odd Only (default is Odd and Even).

Harmonic R

ange. 2 to 100 (default 7). This is the last harmonic used in the

calculation. If Odd Only harmonics are speciﬁed and the Range is set to an

even number, the preceding harmonic will be the last one used.

Harmonic Zero. Exclude or Include (default Exclude)

For the d

istortion settings and harmonics setting, the values will be remembered

whether the actual displayed reading is turned on or off. For example, if the

number of harmonics to be displayed is changed from 7 to 13, turning off and then

on again the display of voltage harmonics will not affect this setting.

The formula for voltage and current THD are:

and

The Total Harmonic Distortion formula (previously called the series formula)

will produce more accurate results for harmonic noise when the THD is less

than 5%. When selecting the THD formula, it is important to set the maximum

harmonics setting to an appropriately large number to get valid results. The higher

the harmonic count the more accurate the calculation.

Telephone inﬂuence factor. The telephone inﬂuencefactor(TIF)isaTHD

measurement weighted at frequencies within the bandwidth of a normal telephone

circuit. It is a measure of how the voltage or current distortion in electrical power

circuits might interfere with adjacent telephone circuits. TIF measurements a re a

requirement of sta ndards such as ANSI C50.13 "Rotating Electrical Machinery -

Cylindrical-R

otor Synchronous Generators" and are most often used o n standby

power generators and UPS. The harmonics included in a TIF measurement are

from1to73oddandeven.

The formula for voltage and current TIF are:

Default refe

rence = Fundamental

40 PA3000 Power Analyzer User Manual