Rockwell Automation 1404-M4_M5_M6_M8 Powermonitor 3000 User Manual, Firmware rev. 3.0 or LATER - Manual (Page 168)

168 Publication 1404-UM001F-EN-P - November 2009
Chapter 8 Advanced Features
TIF
Another method of measuring signal distortion is the Telephone
Influence Factor, sometimes called the Telephone Interference Factor.
This measurement is used to estimate the effect that the power line
harmonics have on nearby analog telephone conductors. This method
weighs each of the harmonics based on the physiological and
audiological characteristics of the human ear. The harmonics are
additionally weighted to reflect the relationship of harmonic
frequency and degree of coupling to the phone lines. These weights
are called single frequency TIF weights. The 1404-M6 uses the most
recent TIF weights (updated in 1960). The single frequency factors are
used to compute the total TIF. You multiply the TIF numbers by the
RMS magnitude of the power lines voltage or current to obtain an
index for estimating the amount of interfering energy that is coupled
to the telephone system. The formula for total TIF is:
TIF
∞
Σ
i 1 =
wiXi ( )
2
∞
Σ
i 1 =
Xi ( )
2
--------------------------- =
Where:
•
X
i
= single frequency RMS current or
voltage at harmonic i.
•
w
i
= single frequency TIF weighting
factor at harmonic i.