Ensuring the proper and efficient functioning of transformers is crucial for maintaining reliable power supply to consumers. Transformer faults can cause severe damage, disrupting power supply and leading to substantial revenue losses. Therefore, it is imperative to identify and adopt best practices throughout the lifecycle of transformers. Effective operations and maintenance (O&M) practices such as regular inspections, oil analysis, temperature monitoring, and protection system checks ensure the longevity and performance of transformers. These practices can help identify potential issues before they escalate into major problems, prevent power interruptions and reduce revenue losses for both manufacturers and utilities.
Notably, some countries have a distribution transformer failure rate of less than 1 per cent, whereas some utilities in India experience a much higher failure rate, reaching 10 per cent. These high failure rates impose considerable financial burdens on utilities due to repair and replacement costs and indirect revenue losses caused by system unavailability. Achieving lower failure rates is crucial for power utilities in the country to facilitate the growth of the power sector. Effective operational practices, combined with the best-suited transformer designs, can minimise transformer failures, ensuring a more reliable and efficient power supply system.
Preventive and predictive maintenance schedules
Preventive and predictive maintenance schedules are crucial for ensuring the reliable and efficient operation of power transformers. Preventive maintenance involves regular inspections, servicing, and component replacements at predetermined intervals or based on manufacturer recommendations. These proactive measures help identify and address potential issues before they escalate into major problems, thereby extending the lifespan of transformers and minimising unplanned downtime. In contrast, predictive maintenance relies on advanced monitoring and diagnostic techniques to assess the transformer’s condition in real time. By analysing data on parameters such as temperature, oil quality and vibration, predictive maintenance can predict potential failures, enabling timely intervention and optimised maintenance efforts. Both preventive and predictive maintenance strategies complement each other, providing power utilities with a comprehensive approach to managing and optimising the performance of critical power transformers. Some operational and maintenance practices that must be included in the maintenance schedule for better performance are given here.
Regular inspections: Frequent inspections of transformers play a vital role in early issue detection, allowing utilities to take preventive measures and avoid potential problems. As a part of essential O&M practices, transformers should undergo regular checks, particularly for signs of overloading, damaged connectors, worn-out power cords, burning smell, loose plugs, or misaligned components. This proactive approach helps minimise system failures and reduces the risk of fire hazards, making it imperative to prioritise these inspections.
Standardisation of operational practices: There are significant variations in the operational practices of utilities, impacting the overall system performance and transformer failure rates. Comparatively, private utilities demonstrate significantly lower failure rates for transformers compared to government-owned utilities.
Analysis of the cause of failure: Transformers can fail for various reasons, and these failures can often be attributed to deficiencies in manufacturing practices or inadequate O&M procedures. Analysing the causes behind these failures is crucial in implementing corrective measures and minimising costs associated with repairs or replacements. To conduct a comprehensive analysis, it is essential to identify the nature of the failure and determine the primary entity responsible for the defect. This systematic approach will enable efficient problem-solving and lead to enhanced transformer reliability and performance.
Digital asset management solutions
In digital asset management solutions, a diverse array of sensors and devices is integrated to continuously monitor essential parameters. These parameters include voltage, current, load conditions, power factor, transformer oil temperature, internal temperature, oil level indicators and the operational status of protection devices. Moreover, remote monitoring and operation are made possible through the utilisation of GPRS, GPS, IoT, or RF-based systems. The incorporation of automatic protection devices ensures that the transformer is safeguarded against abnormal conditions such as overload, overvoltage, short circuits and internal short circuits. Additionally, these solutions feature an energy metering system that enables energy audits and automatic theft detection, making them a comprehensive and indispensable solution for power management.
In utilities where IT enabling initiatives were undertaken as part of government schemes, two IT-based application modules have been successfully implemented. These modules consist of an asset management system and a maintenance management system, both of which offer significant benefits to distribution utilities in enhancing the efficiency of managing their electrical assets.
The maintenance management system plays a crucial role in improving the planning and coordination of various maintenance activities. Adopting preventive and predictive maintenance practices will help reduce breakdowns and enhance the overall reliability of the electrical assets. Additionally, the system maintains a comprehensive maintenance history, allowing for a thorough review and control of maintenance costs. It also offers valuable feedback to the management, enabling timely decision-making processes. In contrast, the asset management system facilitates efficient resource planning, empowering utilities to make swift and accurate decisions in their day-to-day operations. This system enhances the utility’s ability to manage resources effectively and ensures that they respond promptly to operational requirements.
Distribution transformer monitoring unit (DTMU): DTMU, an intelligent device, is designed to continuously monitor specific parameters of transformers. Through advanced communication technology, it transmits this data to the control centre in real time. Parameters such as oil temperature, oil humidity, and oil level can be selected for online monitoring, enabling the early detection of potential issues to prevent transformer failures and mitigate asset losses. By proactively analysing the data, the DTMU facilitates timely actions to prevent failures and address potential issues before they escalate, ensuring the smooth and reliable operation of transformers.
Smart transformers: These transformers have superior control and monitoring capabilities through modern microprocessor-based relays, resulting in increased reliability and system longevity. The inclusion of vacuum fault interrupter control enables seamless communication with control rooms or system networks through standard protocols. These transformers provide continuous diagnostic information, enabling remote monitoring and control decision-making. This capability allows for remote diagnostic assessments and efficient control decisions, making them highly efficient and reliable assets in modern power systems.
Challenges and the way forward
Inadequate operational practices can deteriorate asset health and lead to poor equipment performance. Often, the utilities neglect preventive maintenance, which results in maintenance efforts being initiated only after equipment failure. Apart from this, the absence of mandatory guidelines for the proper installation, operations, and maintenance of transformers often leads to improper earthing practices, the usage of substandard materials in transformer manufacturing, and the overloading of transformers. Moreover, there are instances of tampering or bypassing of protection equipment, along with theft of materials or oil, which can lead to hazardous situations such as fires and eventual transformer failure. These challenges collectively contribute to operational inefficiencies and hinder the reliability of transformers.
To address these challenges effectively, industry experts suggest that manufacturers could extend maintenance services during the warranty period of transformers in selected sample areas. This would not only set the standard for proper transformer maintenance but also enable the utilities’ maintenance staff to receive valuable training and hands-on experience in the best maintenance practices.
Adopting the best O&M practices for transformers is crucial in ensuring the reliability, efficiency and longevity of these critical components in India’s power infrastructure. Regular inspections, uniform operational practices, deploying smart transformers, adopting DTMU and transformer failure analysis are key elements that contribute to the health and performance of transformers. Implementing these practices helps utilities reduce downtime while enhancing their transmission and distribution system’s overall efficiency and sustainability.