Automated self testing of power grid transformer protection systems

A self-testing system for use within an electrical protection circuit comprising:

• the electrical protection circuit electrically connected between a neutral of a transformer and a ground, the transformer electrically connected to a power grid, wherein the electrical protection circuit includes a DC blocking component;
• a test voltage source electrically connected in parallel with the DC blocking component, the test voltage source including a voltage source, a current measurement device configured to determine a current flowing through the DC blocking component, and a voltage measurement device configured to determine a voltage across the DC blocking component;
• and
• a switch electrically connected between the test voltage source and the DC blocking component;
• wherein the self-test system has a testing mode in which the first switch is opened and the switch is closed to introduce a test voltage across the DC blocking component, and wherein an impedance of the DC blocking component is measured and compared to an expected design value in the testing mode.

A self-testing system for use within an electrical protection circuit comprising:

• the electrical protection circuit electrically connected between a neutral of a transformer and a ground, the transformer electrically connected to a power grid, wherein the electrical protection circuit includes a spark gap assembly;
• a first switch electrically connected between the transformer neutral and the spark gap assembly;
• a high voltage source;
• a second switch, wherein the high voltage source and the second switch are electrically connected in series with each other and in parallel with the spark gap assembly;
• wherein, when the second switch is closed and the first switch is opened, a test high voltage is injected across the spark gap assembly to determine a breakdown voltage of the spark gap assembly.

A method for testing an electrical protection circuit electrically connected to a transformer, the method comprising:

• opening an automated motorized or manual grounding switch connecting the electrical protective circuit to the transformer;
• closing a switch connecting a test circuit to a DC blocking component;
• generating a voltage across the DC blocking component;
• measuring an impedance of the DC blocking component;
• comparing the impedance measured to an expected design value of the DC blocking component.