4
voltage U is the product of input reference voltage Uref and K. As K does not affect the
measurement of angle or current magnitude, it can be set to 1, directly displayed as U1. Note that
the correct measurements cannot be obtained when there is no U1 input. For the stored data, the
voltage transformation ratio can be modified, but the modified value only influences the currently
displayed/printed data and cannot be saved.
Test phase difference: the phase difference of the leading fundamental voltage at the
fundamental current includes the compensation angle. MOA performance can be evaluated
according to the angle, and shall be evaluated by deducting the interference angle in case of
interphase interference.
Waveform display
Full voltage waveform
Full current waveform
Resistive current waveform
4. Click “Data View” to display the menu as shown in Figure 7:
0000-A January 5, 2015 08:08:08 001-001
Full V
0.000KV
Full I
0.000mA
Fund V
0.000KV
Res I
0.000mA
Cap I
0.000mA Res fund I
0.000mA
Freq
50.00Hz
Res I3
0.000mA
A Power
0.000W
Res I5
0.000mA
R Power
0.000W
Res I7
0.000mA
Ratio
0.000
Res IMax
0.000mA
Angle
0.000
Diff Phase
0.00
↑
Prev
↓
Next
Y
N
Esc
Figure 7 Data View Main Menu
5. Printout
To print, directly operate according to the screen prompt. In order to facilitate the user to
analyze and save the test data, the instrument saves 100 sets of test data for the user to print.
(After measurement, the user can save the data as required.)
6. Instrument calibration
Enter the password to enter the instrument calibration. Enter the instrument calibration
only when the instrument accuracy is wrong. Do not enter at other times.
7.
Time calibration
January 5, 2015 08:08:08
↑ Change digits ↓ Move cursor
VI. Measurement Principle and Data Analysis
:
The instrument inputs PT secondary voltage as a reference signal and inputs MOA current
signal to obtain the fundamental voltage U1, the fundamental current peak and the current and
voltage angle Φ (Figure 8) by Fourier transformation. The voltage cophase component is resistive
current fundamental value (Ir1p), and the quadrature component is apacitive current fundamental
value (Ic1p):
Ir1p=Ix1pCOSΦ
Ic1p=Ix1pSINΦ
