Application Cases

Experiment Name: Test Experiment of Non-Contact Voltage Divider Unit

Experimental Purpose:
To verify the measurement accuracy of the non-contact voltage divider unit and obtain its voltage division ratio k₂, power frequency voltage tests were conducted on the analog measurement system.

Test Equipment:
High-voltage amplifier, Arbitrary function generator, Oscilloscope, Standard voltage divider, etc.

Experimental Process:

Figure 1: Schematic diagram of the voltage divider unit test wiring

The test wiring schematic is shown in the figure above. The voltage divider unit was installed below a metal plate, with a capacitance value of 0.01 μF. The voltage signal was connected to the oscilloscope input via a coaxial cable with a 50 Ω matching resistor at the front end.

Experimental Results:

Figure 2: Power frequency response of the voltage divider unit

In the power frequency voltage test, a high-voltage amplifier was used to amplify the voltage signal generated by the arbitrary function generator, serving as the voltage source for the power frequency test of the sensor voltage divider unit. The AC voltage applied to the transmission wire was divided by a standard capacitive voltage divider with a ratio of 1250:1 and input into Channel 1 of the oscilloscope. The voltage measured by the non-contact voltage divider unit was input into Channel 2 of the oscilloscope. When the power frequency voltage amplitude output by the combination of the arbitrary function generator and the high-voltage amplifier was 5 kV, the results are shown in Figure 2. The black curve represents the output of Channel 1, and the red curve represents the output of Channel 2.

From Figure 2, it can be observed that the non-contact voltage divider unit can measure the power frequency voltage on the transmission wire in real time. There is a good linear relationship between the input and output voltages, and the output voltage phase of the fabricated voltage divider unit is only slightly ahead of the output voltage of the standard voltage divider.

Figure 3: Fitting curve of input and output voltages of the voltage divider unit

To obtain the actual voltage division ratio k₁ of the voltage divider unit, within the working range of 0–10 kV of the power supply, the amplitude of the AC voltage was gradually increased in steps of 1 kV. A total of 10 sets of input and output data of the voltage divider unit were used for linear fitting, and the fitting curve is shown in Figure 3.

Figure 4: Fitting result data

From the fitting result data table in Figure 4, it can be seen that the input-output linearity of the voltage divider unit is excellent. The measured voltage division ratio of the non-contact voltage divider unit is k₁ = 1395:1, and the coupling capacitance is C₁ = 7.167 pF. These values are close to the coupling capacitance values obtained by the series method and COMSOL simulation, indicating that the parameters of the voltage divider unit are reasonably designed.

High-Voltage Amplifier Recommendation: ATA-7100

Figure: ATA-7100 High-Voltage Amplifier Specifications