Transformer Maintenance Key to Grid Resiliency

Entergy's James A. FitzPatrick
Entergy's James A. FitzPatrick
James A. FitzPatrick Nuclear Power Plant in Scriba, N.Y.


Utilities often struggle with balancing their budgets, including capital for new investments and operational needs to manage existing assets while focusing on reliability. At the same time, emergency outages create rippling effects throughout a system and lead to stretched budgets and concerned customers. Power transformers are one answer to these problems.

Preventative maintenance of transformers with proactive upgrades can provide maximum output and prevent costly repairs or change outs. Utilities that want to capitalize on the benefits of their operations as the smart grid evolves can rely on end-to-end solutions focused on the complete life cycle management of their transformers.

As with all smart grid systems, technology is used to interface with other devices in the network to assist with stability and monitoring. In the event of an outage, the smart grid can locate failures and notify operators. For instance, during a portion of its smart grid implementation to tie in distribution substations throughout the Houston area, a customer required recurring switching at its distribution substations. It needed a solution that could deliver real-time load availability on existing transformers while constantly monitoring the health of the asset to extend their lives. Siemens Smart Grid Services provided a TMDS transformer monitoring and diagnostic system to directly address the issues.

Because of multiple switching cycles, transformers undergo extraneous stress in managing power distribution, which can decrease their life span. Transformer monitoring and diagnostic technology can monitor transformer loads and record data while providing diagnostic tools that can help turn raw data into actionable information. This information is transformed using advanced modeling based on a particular utility’s transmission and distribution system. The technology can help avoid unplanned failures, lower maintenance costs and extend useful transformer life, allowing asset owners to take corrective action before problems occur.

Because of the complex relationships between how the transformer performs and how it is expected to perform during infinite scenarios, system implementation requires expertise in transformers, as well as data integration and analysis. With the right technology, customers gain real-time transformer loading with minimal life reduction, reduced frequency and duration of outages and are moving from time-based to condition-based maintenance.

Such expert monitoring systems can facilitate asset condition-based equipment servicing for extended asset life span. When it comes to equipment servicing, it’s often a misnomer in the industry that a certain company can only work on certain equipment. Fortunately, IEEE standards universally guide technicians, and Occupational Safety and Health Administration regulations prepare everyone, regardless of their affiliation, to do the job safely. Although standards and qualifications are essential, there are many other factors to consider, such as project management skills, individual and group experience, reliability and especially references.

Recently Siemens was called during an emergency outage at generation station in the Northeast when a competitor’s transformer had failed unexpectedly.

Several years prior, Siemens was involved in another project at that station and had provided turnkey installation of a new transformer. This time, however, the customer needed to have its failed transformer disconnected and moved and the spare slid into place. The move was completed in record time, and power was restored to a critical generation station.

An Entergy transformer in Sterlington, La.
A transformer in Sterlington, La.

Ideally, a transformer is replaced just before it reaches its end of life. In reality, however, no matter how scientific a replacement methodology is, forced outages still occur because some transformers fail before their predicted end of life. Once a failure occurs, damage control becomes the top priority. How quickly power can be rerouted or the failed transformer can be replaced will determine the extent of lost revenues.

Having a detailed replacement plan on the shelf can save millions in downtime costs. Even when a spare transformer is available on-site, days might be wasted developing hauling plans, comparing critical dimensions of the spare transformer, performing civil analysis, etc. For a nominal investment, these activities can be planned and can save valuable downtime when a transformer needs to be replaced in an emergency.

No one looks forward to emergency service. It’s costly, time-consuming and has the potential to derail other important tasks. Transformer replacement programs are driven by prioritizing transformers according to their condition and their contribution to network reliability, so transformers in the most critical locations and in the worst condition are the first to get replaced. Utilities must continue their focus on contingency planning and scheduled maintenance, which allow transformers to play a critical role in efficient, reliable power delivery.

Nihit Bhardwaj is the product line manager for transformer life cycle management at Siemens Smart Grid Systems and Services. Reach Bhardwaj at or 919-274-0335.

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