Omicron Lab CT Analyzer, User Manual

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CT Testing Using the Guesser Function
7 CT Testing Using the Guesser Function
This chapter provides a detailed description how to run a CT test using the
guesser function of the
CT Analyzer . Follow the sections 7.2 to 7.5 in the given
order.
For reasons of simplicity, the following example only considers a straight forward
CT test without performing a
burden test , a primary winding resistance
measurement or a residual magnetism measurement .
When working with the CT Analyzer , always observe the safety rules given in
section 2.1 on page 21.
7.1 About the Guesser Function
The guesser function of the CT Analyzer is intended as an aid for the user to find
out single unknown name plate data of a CT, 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.
The guesser function cannot release the user from specifying the CT’s name
plate data prior to testing. Always specify as many CT data as possible to
increase the reliability of the values guessed by the
CT Analyzer !
Warning: Do not touch the equipment under test or the measurement leads
while the red LED on the CT Analyzer is flashing. Never connect or disconnect
measurement leads while the red LED on the CT Analyzer is flashing.
As long as the red LED is flashing, the output is active and lethal voltages can
occur due to the high energy stored in external inductors.
Warning: Always make sure that the CT Analyzer output is connected to the
correct side of the current transformer according to the wiring instructions given
in sections 2.4 and 2.5. Accidentally mixing up the windings can cause life-
threatening voltages within the transformer and/or destroy the connected CT
or the
CT Analyzer !
Warning: Feeding test voltage to a tap of a multi-ratio CT can cause life-
threatening voltages on other taps with higher ratios. Do not touch these taps!
Caution: The data and values determined by the CT Analyzer using the
guesser function are not guaranteed and have to be verified by the user.