Introduction
Keeping transformers in good shape is essential for ensuring reliable power distribution, as they form a crucial part of the electrical infrastructure. Effective maintenance not only extends the life of a transformer but also helps prevent unexpected failures. Over the years, I have learned that a well-structured process makes all the difference. By carefully following a detailed guide, businesses can streamline their maintenance routine and avoid costly breakdowns. Regular testing plays a key role in identifying potential issues early, while comprehensive checklists ensure that no critical steps are missed. From my experience, keeping transformers properly running requires practical tips and proactive strategies, which we will discuss further.
Transformer Maintenance Checklist and Importance
Proper checking of a transformer is a crucial step in ensuring a smooth and uninterrupted power supply. From my experience, regular testing of transformer parts and measurement of parameters help prevent unexpected failures. Many technical teams concentrate on routine tasks to avoid sudden breakdown situations. Following a structured plan makes maintenance more effective and reliable.
A substation relies on well-maintained electrical equipment to function efficiently, making preventative care essential. Routine maintenance is performed at different intervals, such as daily, monthly, quarterly, and yearly cycles. Some actions must be done once every 3 or 4 years, depending on the system’s condition. By following these schedules, maintenance teams can extend the functional life of transformers.
Workers handling transformer maintenance must focus on both routine and emergency repairs. If condition maintenance is done properly, it helps avoid sudden failures that require urgent attention. A group of skilled personnel ensures that all required checks are done thoroughly. Neglecting these tasks may lead to costly downtime and unnecessary breakdown situations.
With 100% focus on maintenance, the chances of failure become 0%, ensuring consistent performance. Power distribution systems depend on well-maintained equipment, which is why maintaining a proper schedule is vital. Half-yearly and yearly inspections, along with periodic actions, keep transformers in optimal condition. A structured approach ensures efficiency, safety, and long-term reliability.
Daily Inspection and Checks
The MOG reading of the main tank and conservator tank should be checked daily to ensure the oil level is not unsatisfactory. If needed, fill the transformer with oil and check for any leaks at critical points.
Inspect the breather and observe the color of the silica gel; if it turns pinkish, it is necessary to replace it. This prevents moisture from affecting the power system.
If leakage is found in the main or conservator tank, take immediate action to plug the issue and secure the system. Maintaining a sealed system helps prevent long-term failures.
Daily Magnetic Oil Gauge inspections are crucial for transformer reliability. Keeping track of these three key aspects ensures smooth operation and extends the equipment’s life.
Monthly Inspection and Care
The oil level in the transformer must be checked at one-month intervals to ensure smooth operation. If the oil inside the cup is found below the specified mark, it must be topped up to maintain the correct condition.
The breather and breathing holes in the silica gel cap must be properly cleaned if required. This helps maintain proper airflow, ensuring the power system functions without issues.
If the bushings contain oil, they should be visually inspected using the attached gauge. If necessary, filling should be done under shutdown conditions to keep the system stable and safe.
Half-Yearly Transformer Maintenance
To keep the transformer in good condition, the oil must be checked every 6 months for dielectric strength, acidity, flash point, resistivity, and IFT levels. The DDA test helps identify contamination and sludge buildup, ensuring smooth operating conditions. While maintenance is required for most transformers, distribution transformers under light load during non-peak hours often require less attention. Monitoring water content regularly ensures long-term efficiency and reliability.
Yearly Transformer Maintenance
Inspect all bushings and check for crackling or damage; any issues must be examined and fixed to ensure safety.
The BDV and DGA tests should be performed on oil samples to analyze dissolved gas and dielectric strength levels.
Cooling pumps and fans must be checked for proper operating conditions to avoid overheating issues.
WTI and OTI indicators should be inspected, and if needed, oil in pockets must be replenished to maintain accuracy.
Marshalling boxes must be cleaned, and all contacts, relays, and alarms should be tested for proper functioning.
Resistance and polarization index should be measured using a 5 kV megger to ensure insulation quality.
All RTCC and control panels should be investigated for wiring and circuit integrity, fixing any issues found.
The pressure release device and Buchholz relay must be tested with shorted contacts and wires to confirm safety.
OLTC oil should be inspected and replaced if the PPM of moisture is high or low dielectric strength is detected.
The earth riser should be measured using clamps to check for proper grounding resistance levels.
Calibration of tan delta values for bushings should be done every two years to prevent failures.
The temperature system, including airflow and heaters, must be tested to avoid equipment damage.
Drain and filter transformer oil regularly to maintain its physical condition and avoid contamination buildup.
Maintenance of Current Transformer
A Current Transformer (CT) is an essential piece of equipment in an electrical substation, ensuring accurate measurement and protection of the system. If not properly maintained, it may cause disturbances due to malfunctioning relays, leading to faults in the operation of the power network. To perform effectively, maintenance should be performed at one-year intervals, following a structured schedule. Experts discuss and follow a preferred reference to keep CT units installed in working condition for smooth performance.
The insulation resistance of the CT should be checked on a yearly basis to ensure the transformer is in optimal condition. Primary insulation is designed to withstand high voltage as it deals with the full system load, and it must be measured using a 2.5 or 5 kV megger. On the other hand, the secondary insulation, with a 1.1 kV level, is low, so it is measured using a 500 V megger.
Both primary to secondary and primary to earth resistances should be checked, while the secondary cores, as well as the connections, are measured with a 500 V megger. Proper protection of terminals and cores is essential to prevent issues related to earth resistances. This ensures the current transformer continues to operate effectively without risks.
For half-yearly maintenance, thermovision scanning of the primary terminals and top dome of the live CT should be performed. This can be done with the help of an infrared camera to detect any irregularities or overheating. Ensuring maximum resistance and proper functionality is crucial, especially in the primary connections.
The secondary connections in the CT junction box and CT secondary box need to be checked, cleaned, and tightened at least once every year to prevent any issues. This guarantees a low-resistance path for the currents. Always ensure the box is properly cleaned to maintain the system’s efficiency and prevent future malfunctions.
Voltage Transformer and Capacitor Voltage Transformer Maintenance
The construction of a voltage transformer and a capacitor voltage transformer (CVT) is similar, which means the maintenance scheme for both types is also largely the same. Since current does not flow heavily through PT and CVT, the chances of defects or faults are generally very low. Therefore, monthly maintenance of the voltage transformer and CVT may not be required unless there is a specific issue.
Frequent maintenance of bus PT or CVT may not be feasible because taking a shutdown of these components would temporarily remove the protection and metering of the entire bus section. Instead, yearly maintenance is usually sufficient to keep the equipment running smoothly and to prevent any major issues from arising.
Yearly maintenance of voltage transformers or capacitor voltage transformers
Housing of the transformer should be cleaned using cotton cloths to maintain the unit.
The spark gap assembly must be checked yearly to ensure it functions properly.
The thermal camera is used for detecting hot spots in the capacitor stacks, ensuring rectification if necessary.
Terminal connections, including earth connections in the PT junction box, should be checked for tightness.
Gasket joints should be visually inspected and replaced if they are damaged or found to be faulty.
Lastly, check the tan δ value, as an increase in this value indicates deterioration in insulation and the possible entry of moisture.
For yearly maintenance, it’s important to regularly inspect electrodes and connections for wear, ensuring that spark gaps and gaskets are in optimal condition. Checking the earthing point and the frequency of the capacitor stack is essential to prevent any moisture buildup that can affect the insulation and the overall health of the transformer.
Conclusion
In conclusion, yearly apacitor voltage transformers and transformer maintenance is crucial for ensuring their efficient performance and long-term reliability. Regular tasks such as cleaning the housing, checking the spark gap assembly, inspecting gasket joints, and using a thermal camera to detect hot spots help prevent potential issues. It is essential to check terminal connections, earth connections, and tan δ values to monitor insulation health and detect any moisture or deterioration. Proper maintenance ensures smooth operation and avoids disruptions in the power system.
