Substation maintenance is a process of periodic, planned inspection of and, if necessary, repair, and replacement of all switchgear, buildings, and ancillary equipment in substation installations. In simple terms, substation maintenance is a regimen of regular preventative checks and actions carried out to ensure substations are kept in good working order. This process typically consists of a series of stringent visual and physical inspections and actions carried out according to a set schedule. Equipment replacement may be standard procedure or only upon detection of wear, damage, or substandard operation. All inspection and actions during substation maintenance should be accurately documented and stored for further reference.
Substations are the most critical part of any electrical supply grid. A failure of a single piece of substation equipment can cause a total grid collapse which may take days or even longer to rectify. For this reason, substation care is one of the most important parts of any electrical department’s preventative maintenance schedule. These schedules generally consist of a tiered plan of minor and major maintenance events. Minor maintenance will seldom require any sort of power shut down although major events typically requiring short intervals of supply interruption.
Routine or minor substation maintenance is usually carried out on a weekly or bi-weekly basis. It typically consists of visual checks and superficial cleaning only. Checks would include visual confirmation of the general condition of switchgear, earthing mechanisms, transformers, insulating liquid levels, and lightning arrestors. A general system performance check can also be carried out using any installed software or by reviewing incoming and outgoing meter readings. These checks are generally implemented in accordance with a set checklist and all findings are noted and filed.
Major substation maintenance involves more planning and is generally handled on a quarterly basis. In the case of industrial installations, these procedures are often carried out during plant maintenance shutdowns. Residential substations are a little more difficult to plan for and generally require switching the supply over to auxiliary equipment during the process. During these maintenance events, a more detailed checklist is followed which requires checking and testing individual substation components. This will typically require isolating individual circuit breakers and checking racking mechanisms, overcurrent and earth leakage protection, and contact integrity.
Ancillary equipment such as amp and volt meters, control circuits, and transformers will also be given individual attention during this review. Insulating liquids such as transformer and circuit breaker oil are also checked for contaminants, dielectric breakdown values, and dissolved gas content. In addition, cable trays and trenches as well as the bus bar sections of the substation are cleaned, and all bolted connections checked for correct torque settings. A 500 or 1000 volt insulation resistance test will also take place for all circuit breakers and cables during. All major maintenance work and inspections are recorded and filed for reference.