How Should the Transformer Online Monitoring Retrofit Project Be Implemented? A Roadmap from Pilot Projects to Full-Scale Deployment

• Characteristics of the Renovation Project: Online monitoring retrofits involve installing monitoring systems on equipment already in operation, with the key constraint being that they must not affect the safe operation of the existing equipment. The challenges of project management lie in coordinating multiple stations, utilizing power outage windows, and evaluating the results of the retrofits.
• A phased approach is a best practice: First, conduct pilot projects to verify effectiveness; then, summarize lessons learned to establish standards; next, roll out the initiative on a large scale to reduce costs; and finally, continue to optimize, iterate, and upgrade the system. Avoid the high-risk approach of achieving full coverage in one go.
• Three Key Roles: Management support in the form of resources and policy guarantees; involvement of the operations and maintenance team to ensure the system will be used once it is built; and cooperation from suppliers to ensure technical and after-sales support

1. Phased Implementation Plan

1.1 Pilot Phase—Select 1–2 representative substations as pilot sites and install all planned monitoring parameters. Operate the system for six months to one year to accumulate data and experience, and verify the system’s reliability and diagnostic accuracy. The goal of the pilot phase is not to maximize the number of sites, but to validate the feasibility of the solution, refine implementation processes, and train the operations and maintenance team.

1.2 Promotion Period—Based on lessons learned from the pilot phase, adjust and optimize the deployment plan and roll it out in bulk at substations of the same type. Leverage economies of scale to reduce unit costs and implementation expenses. Implementation efficiency during the rollout phase is significantly higher than during the pilot phase, as the plan has been validated, processes have been standardized, and the team has gained experience.

1.3 Optimization Period—Optimize alarm thresholds and diagnostic models based on extensive operational data. Formally incorporate online monitoring data into the condition-based maintenance decision-making process to achieve a closed-loop system from development to application.

2. Key Considerations During Implementation

2.1 On-site Inspection First—Site conditions vary from substation to substation. Before installation, a site survey must be conducted to confirm the following: the specifications of the transformer sampling valve and temperature sensor socket interfaces, the available installation space, the location and capacity of the power supply, and the communication network access points.

2.2 Priority Given to Installation Without Power Outage—External sensors (such as ultrasonic sensors, high-frequency CT sensors, and surface-mounted temperature sensors) support installation without power interruption, which can significantly reduce the impact of retrofitting on power supply. Sensors that must be installed during a power outage should be installed during scheduled power outage windows.

2.3 Putting Data to Practical Use—The biggest concern with retrofitting projects is that, once the equipment is installed and the acceptance inspection is passed, no one monitors the data. From the very beginning of the project, it should be clearly defined who on the operations and maintenance team is responsible for monitoring the data on a daily basis and how to respond to anomalies. Efforts should be made to incorporate online monitoring data into the operations and maintenance performance metrics.

3. Frequently Asked Questions FAQ

3.1 Q: Does the transformer have to be taken offline during the retrofit?

Answer: Most external sensors support installation without power interruption. Power must be shut off only in special cases involving internal modifications to transformers. For renovation projects, solutions that support installation without power interruption should be prioritized.

3.2 Q: Which requires a larger investment: renovation or new construction?

Answer: Retrofits typically involve higher costs than new construction—because they require adaptation to existing equipment interfaces and on-site conditions. However, retrofits avoid the high costs associated with civil engineering and primary equipment investments required for new substations. The cost of retrofitting for online monitoring represents a very small percentage of the transformer’s total value.

3.3 Q: How are pilot sites selected?

Answer: Select sites that are highly representative—covering a wide range of voltage levels and typical operating conditions. Avoid selecting sites with conditions that are too specific or too ideal, as this would make it difficult to generalize the lessons learned from the pilot program.

Disclaimer: The content of this document is provided solely for technical exchange and reference purposes and does not constitute any form of purchase commitment or contractual offer.

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