CPOL2 battery
5.9 CTRogowski (ratio)
5.9.1 Test settings
Figure 5-23:CTRogowski test card with test results
Navigate to the parameter fields, and enter the values according to your test requirements:
Note:When using the CTRogowski test card, the 3V V2 AC input uses an additional software-based integration method.
In the range of 50 Hz < f < 60 Hz, this results in a phase shift of 90° as well as an additional phase error of ±0.1° and an additional amplitude error of ±0.01%. For frequencies in the range of
15 Hz < f < 400 Hz, the phase error is not specified, and the amplitude error can be up to ±0.50% higher.
Therefore, for phase measurements, use a frequency range of 50 Hz < f < 60 Hz only.
Pressing the Settings menu key opens the Settings page. The Settings page allows setting the test cards individually. As a rule, do not use the Settings page but the Device Setup tab in the Options view (see "Device Setup" on page 56) to set the test cards. For more information, see "Settings page" on page 50.
Within the Settings menu, you can set correction factors in accordance with IEC 61869-10. The measured transformation ratio of the instrument transformer under test can be adjusted with the Range: output range
Iprim:
(upper field)
nominal primary current of Rogowski coil Vsec: nominal secondary voltage of Rogowski coil
fnom: nominal frequency of the Rogowski coil’s secondary voltage Itest: primary injection current
f: frequency of injected current Itest
Auto: select check box for automatic test (default), clear for manual test (refer to page 122).
5.9.2 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 V2 AC.
Iprim:
(lower field)
actual output current at the output that is injected into the Rogowski coil’s current-carrying conductor
Vsec: secondary voltage measured at V2 AC I’sec: calculated secondary current. I’sec =
with k = Iprim nom / (Vsec nom × 1 s).
Note:The current I’sec does not really exist in the system. It is a calculated current only.
° phase angle of calculated secondary current with reference to the primary current Ratio: Iprim / I’sec × CFI1, here: 10.0:9.982
1. CFI stands for the amplitude correction. By default, it is set to 1.00 and subsequently no additional ratio error is considered.
2. The value 9.98 is calculated as follows:
(I’sec / Iprim) × Iprim nom ×CFI, here: (9.86 A / 10 A) × 10 A ×1.012 = 9.98 A
Ratio error:
Note:Results are marked with an exclamation point (!) if a correction factor was used.
Phase error: φ = φIsec – φIprim – φPhase correction3
3. By default, the phase correction is set to 0.0000° and subsequently no additional phase error is considered. Here: 0.00°, including 90° integration phase shift.
Polarity: Displays the status of the polarity
OK = phaseI’sec – phaseIprim = –45° < 0° < 45°
NOT OK = all other cases
k V sec d t
ε I'sec×CFI–Iprim Iprim
--- 100%×
=
5.9.3 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 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 seconds.
► The automatic test stops by itself, it can now be assessed.
► To repeat the test, first press Back to Top, if applicable, and then Clear Results.
Manual test
Clearing Auto lets you set the test current Itest manually with the handwheel.
► Press the I/O (test start/stop) push-button to start the test. The focus is set onto the "I test:" entry field.
► Set the value of your choice either by turning the handwheel and/or by entering it with the numerical keys.
► A value set with the numerical keys needs to be fully entered and acknowledged by pressing either Enter or the handwheel before it is applied to the output. If needed, it can then be adjusted using the handwheel.
Values set by turning the handwheel are applied instantaneously.
► Now the measurements are taken and displayed.
► To save the measurement press Keep Results (pressing the I/O push-button has the same effect).
The last measured values are "frozen", the test can now be assessed.
► Stop the manual test by pressing the I/O (test start/stop) push-button.
► To repeat the test, first press Back to Top, if applicable, and then Clear Results.
2. Option "Manual input" selected
Note:Select "Manual input" prior to starting the test. If the test card still contains results, clear them by pressing Clear Results. When "Manual input" is selected, there is no phase available. Consequently, neither the polarity nor the phase angle can be calculated.
Since an automatic test only lasts a very short period of time, and a manual measurement is rather difficult, an automatic test with a manual measurement is not useful. Therefore, this Reference Manual will not cover this subject.
Manual test
Clearing Auto lets you set the test current Itest manually with the handwheel.
► Press the I/O (test start/stop) push-button to start the test. The focus is set onto the "I test:" entry field.
► Set the value of your choice either by turning the handwheel and/or by entering it with the numerical keys.
► A value set with the numerical keys needs to be fully entered and acknowledged by pressing either Enter or the handwheel before it is applied to the output. If needed, it can then be adjusted using the handwheel.
Values set by turning the handwheel are applied instantaneously.
► Iprim is measured and displayed.
► To save the measurement press Keep Results.
► Navigate to the Vsec entry field.
► Enter the measured Vsec value either by turning the handwheel or by entering this value with the numerical keys, and press Enter or the handwheel to acknowledge your setting.
► The ratio is calculated and displayed.
► To stop the manual test, press the I/O (test start/stop) push-button. The test can now be assessed.
► Alternatively it is possible to enter the manually measured value into the test card after the test was stopped (for example, if the measurement was carried out at a remote location).
► To repeat the test, first press Back to Top, if applicable, and then Clear Results.
To learn more about test assessment, refer to 10.1 "Test assessment" on page 268.