Omicron CPC 100, Reference Manual

Page: 143 / 382

Voltage Transformer
5 - 5
Measurements
Selecting the check box "Manual input" lets you enter the value for Vsec
manually, for example when Vsec was measured with an external volt meter
rather than at input
V1AC .
Automatic Test vs. Manual Test
1. Option "Manual input" clear
Automatic test
– Press the I/O (test start/stop) push-button to start the test.
The test voltage increases from 0V to Vtest in a ramp characteristic within
1 second. Then Vtest is kept for a period of 2.4 seconds, and the
measurements are taken. Next, the ramp decreases again within 0.3
seconds.
– The automatic test stops by itself, it can now be assessed.
– To repeat the test, first press B
A C K T O
T
O P
, if applicable, and then C
L E A R
R
E S U L T S
.
Manual test
Clearing "Auto" lets you set the test voltage Vtest manually with the handwheel.
Vprim: actual output voltage at 2kV AC output that is injected into the
voltage transformer’s primary side
Vsec: secondary voltage measured at V1AC, and its phase angle
relative to Vprim nominal
Ratio:
ratio Vprim /Vsec., here 10000.0/
√
3:100.43/
√
3
1
1. The value 100.43/
√
3 is calculated as follows:
Vsec act * (Vprim nom / Vprim act) = 20.087V * (10000V / 2kV) = 100.43/
√
3
and deviation of voltage ratio in %. Formula:
((Kn x Vsec - Vprim) / Vprim) x 100%
2
((10000V / 100V * 20.087V - 2000V) / 2000V) x 100% =
0.431%
2. Kn = rated transformation value, here: 10000V / 100V
Polarity: displays the status of the polarity
OK = phaseVsec - phaseVprim = -45° < 0° < 45°
NOT OK = all other cases