Method and system for assessment of fault severity, risk exposure, and gassing status for liquid-filled high-voltage apparatus

A Method for Assessment of Fault Severity, Risk Exposure, and Gassing Status for a Liquid-Filled High-Voltage Apparatus, comprising:

• taking a series of samples from a liquid-filled high-voltage apparatus at intervals over a time period;
• performing a gas analysis on each of the samples to measure concentrations of selected gases;
• storing in electronic form (called “the database”) a data record for each sample containing the gas concentration measurement values pertaining to that sample as well as information (sufficient for calculating time intervals between samples) as to when the sample was collected.
• programming a computer:
• to calculate a fault energy index value for each of any number of selected sample data records in the database based upon the gas concentrations in the data record that are required for the calculation;
• to search the sample data records pertaining to a selected apparatus in the database and tabulate the initial and final dates and initial and final fault energy index values of time intervals (“gassing events”) in which there is production of fault gas by the apparatus leading to a net increase in the fault energy index spanning the time period between the initial date and the final date;
• to calculate a severity of a gassing event proportional to a conditional probability of failure derived from a reliability model comprising a random variable representing failure-related values of the fault energy index;
• to calculate a gassing status code for the apparatus based on the time of occurrence and the severity of gassing events for that apparatus.