98
Working with Broadcast Data
where the denominator now includes the sum of rms harmonic voltages plus the fundamental.
K–FACTOR
is a weighting of the harmonic load currents according to their effects on transformer
heating, as derived from ANSI/IEEE C57.110.
A K–Factor of 1.0 indicates a linear load (no
harmonics). The higher the K–Factor, the greater the harmonic heating effects. It is calculated
based on the following equation:
(9.5)
K
−
F actor
=
(
V
1
×
1)
2
+
· · ·
+ (
V
50
×
50)
2
V
2
1
+
· · ·
+
V
2
50
where each component is multiplied by the harmonic number (
e.g.
1
,
2
,
· · ·
,
50), called a
weighting factor.
9.5.2
Harmonic Load Currents
Harmonic load currents significantly affect power distribution system design. Harmonics create
additional losses through the skin effect at high frequencies and through higher RMS load currents.
By specifying K–Rated transformers and using other techniques, power distribution systems and
customer equipment should have lower failure rates.
9.5.3
Harmonic Summary Data
Harmonic Summary data returned from the 1133A can be a strong indicator of what harmonics
are being returned to the distribution system location by users with non-linear loads. Harmonic
content is potentially damaging both to the power company and the user. If adequate protection
is not taken, equipment will experience early failure and also lower overall efficiency.
9.6
Logging Waveform Data
Waveform Data includes all of the values shown in the Broadcast Data window. When activated,
the window allows individual selection of current or voltage using the Input Toolbar buttons.
Waveform data are synchronized to the GNSS, broadcast at a rate of 640 samples per second and
simultaneously saved in a file of choice. See Figure 9.10.
Figure 9.10: Waveform Data Screen
