Omicron Lab CT Analyzer User Manual page 118

CT Analyzer User Manual
116
By pressing one of these soft keys you can display the measured
excitation graph and knee point as defined in the respective
standard.
IEEE C57.13 displays the knee point for the 45° tangent. After
pressing this soft key, its labeling changes to IEEE C57.13 (30°) to
enable the display of the knee point for the 30° tangent. 30° is
recommended for gapped cores in IEEE C37.110, chapter 4.3.
Note: The test report only contains the graph for the standard
selected in the CT-Object card.
Viewing the measured values for different points on the graph
By default, the knee point values are displayed after opening the excitation
graph page. However, you can also view the corresponding voltage, current and
inductance values for any point on the graph. To select a specific point on the
graph,
• either use the soft keys (Cursor Up, Cursor Down, Knee Point)
• or enter a specific voltage or current value using the keyboard:
– Select the desired edit field using the
– Enter the desired voltage or current value using the keyboard.
– Press the key to apply the entered value and read the
corresponding values in the respective fields (e.g. "V-meas" and "L-meas"
if you have entered a current "I-meas").
Figure 6-14 Entering a current value to display its corresponding voltage
and inductance values on the excitation graph
cursor keys.