Method and device for testing a galvanic connection of a high-voltage condenser bushing assembly

1. A method for testing the quality of a galvanic connection between a first terminal and a conductive layer of a high-voltage condenser bushing assembly, the method comprising:

providing a capacitive test circuit, wherein the capacitive test circuit comprises the first terminal, an AC power source and a measurement unit;

providing, by the AC power source, a first test current in the capacitive test circuit, wherein the first test current is an AC current at a first test frequency of 10 kHz or higher;

measuring, by the measurement unit, a test parameter indicative of a resistance of the galvanic connection; and

determining the quality of the galvanic connection from the measured test parameter.

2. The method according to claim 1 , wherein the galvanic connection comprises a soldered contact, wherein the method comprises determining the quality of the soldered contact.

3. The method according to claim 1 , wherein the AC power source has an opening voltage of 50 V AC or lower.

4. The method according to claim 1 , wherein the first test current is 0.1 A AC or higher.

5. The method according to claim 1 , wherein the first test current has a magnitude configured to destroy a defective galvanic connection, wherein the method further comprises:

determining whether the galvanic connection was destroyed by the first test current.

6. The method according to claim 1 , wherein the test parameter is indicative of an effective capacity of the capacitive test circuit, wherein the method further comprises:

comparing the measured test parameter to a predetermined threshold value indicative of a threshold capacity;

determining that the galvanic connection is defective, if the measured test parameter is smaller than the predetermined threshold value; and

determining that the galvanic connection is not defective, if the measured test parameter is greater than or equal to the predetermined threshold value.

7. The method according to claim 1 , wherein the first terminal is a mounting flange of the high-voltage condenser bushing assembly.

8. The method according to claim 1 , wherein the capacitive test circuit comprises a second terminal of the high-voltage condenser bushing assembly, wherein the second terminal is a voltage tap of the high-voltage condenser bushing assembly.

9. The method according to claim 8 , wherein, in the capacitive test circuit, the AC power source and/or the measurement unit are arranged in series between the first terminal and the second terminal.

10. The method according to claim 1 , wherein measuring the first test parameter comprises performing a C2 measurement, which involves measuring a capacitance value between two conductive layers of the high-voltage condenser bushing assembly.

11. The method according to claim 1 , wherein the first test parameter comprises at least one of the following:

a current flowing the capacitive test circuit;

a voltage drop in the capacitive test circuit;

a capacitance of the capacitive test circuit;

an impedance of the capacitive test circuit; and

a resonant frequency of the capacitive circuit.

12. The method according to claim 1 , wherein the capacitive test circuit further comprises an inductance, wherein the first test frequency is substantially a resonant frequency of the capacitive test circuit.

13. The method according to claim 1 , wherein the capacitive test circuit further comprises an inductance, wherein the method further comprises:

adjusting a test frequency, wherein the adjusted test frequency is 10 kHz or higher,

wherein measuring the test parameter comprises:

measuring, by the measurement unit, a response of the capacitive test circuit to the adjustment of the test frequency; and

determining a resonant frequency of the capacitive test circuit.

14. The method according to claim 1 , wherein the first test current is an AC current selected at a first test frequency of 20 kHz or higher.

15. A testing device performing the method of claim 1 , the testing device being configured for testing the quality of a galvanic connection between a first terminal and a conductive layer of a high-voltage condenser bushing assembly, the testing device comprising:

an AC power source configured to operate at a frequency of 10 kHz or higher;

a measurement unit; and

a control unit,

wherein the testing device is configured to be electrically connected to the first terminal and to a second terminal of the high-voltage condenser bushing assembly, thereby providing a capacitive test circuit, the capacitive test circuit comprises the first terminal, the AC power source and the measurement unit,

wherein the AC power source is configured for providing a first test current in the capacitive test circuit, the first test current is an AC current at a first test frequency of 10 kHz or higher,

wherein the measurement unit is configured for measuring a test parameter indicative of a resistance of the galvanic connection,

wherein the control unit is configured for determining the quality of the galvanic connection from the measured test parameter.