Current Transformer
4 - 7
Figure 5:
CTRatio test card with
selected "Measure
burden" option and test
results
Additional measurements when "Measure burden" is selected
Automatic Test vs. Manual Test
1. Option "Manual input" clear
1
Automatic test
– Press the I/O (test start/stop) push-button to start the test.
The test current increases from 0A to Itest in a ramp characteristic within
1 second. Then Itest is kept for a period of 2.4 seconds, and the
measurements are taken. Next, the ramp decreases again within 0.3 second.
– The automatic test stops by itself, it can now be assessed.
– To repeat the test, first press B
ACK TO T OP, if applicable, and then C LEAR
R
ESULTS.
Vsec: measured secondary voltage and phase angle relative to Iprim
Burden: burden in VA: Isec nom × (Vsec act × Isec nom/Isec act)
cos
ϕ cosine of angle between Isec and Vsec
1. Refer to ”Three methods to determine I sec” on page 5 of this chapter.
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