OMICRON 125
Test cards for Advanced CT Test mode
8.7 Ratio card
The Ratio card of the Advanced CT Test mode is only available if it is enabled in the Select Cards page
(Default Test Settings or Select Cards soft key in the CT-Object card).
The ratio test measures the current ratio of the CT considering the operating burden (parameter
"Burden" in CT-Object card) or the nominal burden (parameter "VA" in CT-Object card).
The results of the ratio test can be found in 3 pages:
•The Ratio card (refer to Figure 8-16) shows the polarity, the ratio error and the phase displacement
for the primary current and the burden defined in the CT-Object card.
If the Results with Nom. Burden soft key is pressed, the page shows the results related to the
nominal burden ("VA" parameter in the CT-Object card). If the Results with Op. Burden soft key is
pressed, the page shows the results related to the operating burden ("Burden" parameter in the
CT-Object card).
•The ratio table shows the current ratio error for different currents (200% down to 1% of the rated
current) at different burden values (depending on the selected standard, see section 8.7.4 on page
128 and 8.7.5 on page 129).
•The phase table shows the phase displacement for different currents at different burden values
(depending on the selected standard, see section 8.7.4 on page 128 and 8.7.5 on page 129).
For a better understanding of the test results, the most important settings from the CT-Object card are
shown once again in the upper part of the Ratio card.
Note: Although the test is not performed with the real current, the test results reflect the current ratio and
not the voltage ratio.
Figure 8-16: Ratio card
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