CP SB1 User Manual
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For power transformers, the following test cards are available:
Figure 3-1 Inserting test cards
Highlight the test card of your choice either by navigating with the handwheel or
by using the context-dependent Up/Down menu keys, and then press Enter.
Note: The test card TRRatio (per Tap) employs the frequency-selective
measurement method, which is used to filter out interferences usually present in
substations.
Note: To learn more about the frequency-selective measurement, refer to "The
Frequency-Selective Measurement" in the CPC 100 Reference Manual.
3.4 TRRatio Test Card
Use the TRRatio test card to measure the ratio of power transformers by
injecting AC voltage from AC OUTPUT into the transformer’s high-voltage side.
The maximum voltage for Y and D transformers is limited to 300 V, and for YN
transformers to 150 V.
The CPC 100 measures both the voltage it applies to AC OUTPUT and the
transformer’s low-voltage side at V1 AC. From these values, it calculates the
ratio and its deviation from the nominal ratio in percent.
In addition, the excitation current and its phase angle is measured. Moreover,
the phase angle between the high-voltage and the low-voltage side is measured.
Furthermore, you can use the TRRatio test card to measure a power
transformer’s ratio for each single tap changer position.
3.4.1 "Test Settings for TRRatio" on page 38 shows the Vprim and Vsec settings
on the TRRatio test card for different connections of the transformer under test.
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