CT Analyzer User Manual
14 OMICRON
If the CT design type is unknown, OMICRON recommends to reconfirm the CT characteristics
beforehand and/or to perform an initial calibration between direct and indirect method for the certain CT
type.
As an example, the so-called factor of construction mentioned in IEC 61869-2 indicates if the CT is of
low or high leakage flux. Below the specified limit, both test methods (direct and indirect) provide similar
results.
In all other cases, there might be differences between the direct and the indirect test method and an
initial calibration, documentation of results, and later consideration of the differences is recommended.
Following this procedure, the high reproducibility of CT Analyzer even allows to apply CT Analyzer for
traceable CT calibration.
2.2 "Guessing" of parameters
The Advanced CT Test mode of CT Analyzer provides a so-called guesser function which is intended as
an aid for the user to find out single unknown name plate data, for example if parts of the CT’s name
plate are unreadable. If sufficient other name plate data of the CT are available and specified by the user,
this function is often able to reliably determine single missing CT data, for example I
prim
, I
sec
, class or
ratio.
Parameters that are guessed by CT Analyzer are marked by a question mark in the user interface of the
CT-Object card prior to the test. To have a parameter guessed by CT Analyzer, select the ? soft key
instead of specifying a value for this parameter. During the test, CT Analyzer replaces the question mark
by the value guessed.
When using this function, please be aware that assessments performed with one or more
guessed parameters may possibly differ from an assessment based on exact name plate data.
Absolutely reliable assessment is only guaranteed if all necessary CT data are specified prior to
the test.
For detailed information about the guesser function, please refer to chapter 9 on page 138.
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