System and method for controlling and monitoring parallel surge arresters and bushings of a power transformer and motor

A method of protecting electrical equipment from over-voltage transients from a power source using an over-voltage protection system, the method comprising:

• protecting a protection circuit comprising:
• a first electrical bus, wherein the first electrical bus is energized by the power source;
• a second electrical bus configured to feed power to the electrical equipment;
• a first surge arrester and a second surge arrester arranged in parallel, the first surge arrester having one end electrically connected to the first electrical bus via first normally closed contact and having an opposite end connected to ground, the second surge arrester having one end electrically connected to the first electrical bus via a second normally closed contact and having and an opposite end connected to ground;
• a main bushing and a backup bushing, wherein the main bushing is connected between the first electrical bus and the second electrical bus by a third normally closed contact, wherein the backup bushing is connected between the first electrical bus and the second electrical bus by a first normally open contact, wherein the first normally open contact is provided in series with the bushing and configured to isolate the backup bushing from at least one of the first electrical bus and the second electrical bus while in an open state and is configured to electrically connect the backup bushing to the one or more of the first electrical bus and the second electrical bus when in a closed state;
• a controller configured to selectively open or close one or more of the first normally closed contact, the second normally closed contact, the third normally closed contact, and the first normally open contact;
• and
• a tan delta tester operatively connected to the controller and configured to test an insulation property of one or more of the first surge arrester and the second surge arrester, and an Insulation Resistance (IR) tester operatively connected to controller and configured to test an insulation property of one or more of the main bushing and the backup bushing;
• periodically measuring, by the controller using the tan delta tester, the insulation property of each of the first and second surge arresters individually, wherein measuring the insulation property of a given surge arrester among the first surge arrester and second surge arrester includes:
• isolating, by the controller, the given surge arrester from the protection circuit, and maintaining another surge arrester among the first and second surge arresters in service in the protection circuit while the given surge arrester is isolated, wherein the first surge arrester is isolated by opening the first normally closed contact and the second surge arrester is isolated by opening the second normally closed contact,
• measuring, by the controller using the tan delta tester, the insulation property of the given surge arrester, and
• determining, by the controller, a status of the given surge arrester's insulation based on the measured insulation property;
• in response to determining that the status of the given surge arrester's insulation is acceptable,
• placing, by the controller, the given surge arrester back into service, wherein the first surge arrester is placed back into service by closing the first normally closed contact, and wherein the second surge arrester is placed back into service by closing the second normally closed contact;
• and
• in response to determining that the status of the given surge arrester's insulation is poor,
• outputting, by the controller, an alarm indicating the status of the given bushing, and
• maintaining the given surge arrester in an out of service state.