Introduction
The United States of America’s Capital, Washington D.C., is served by a major east coast utility. That utility was facing the possibility of a high-impact event, namely the loss of a 500,000 volt, 392 MVA transformer, serving government offices, local population, retail, commercial and industrial operations. Washington D.C. avoided a major power outage by using a Dynamic Ratings online transformer bushing monitoring system.
The Challenge
This east coast utility deployed Dynamic Ratings online transformer monitoring, control and communications on many of its critical transformer assets. The Dynamic Ratings bushing health monitor was found to be displaying a “bushing health monitor alarm” locally on its operator interface and on the utilities remote panel annunciator in the control building.
The bushing health monitor was measuring elevated power factor and capacitance values from the (X3) bushing, on the 138,000 volt side of the transformer. This prompted the need for immediate investigation. The customer removed the subject transformer from service.
The Solution
The utility allocated resources to perform offline testing. The offline testing (100%) confirmed and validated the Dynamic Ratings monitoring solution’s collected data and validated its alarmed state. The utility dispatched a crew to replace the failing bushing. In addition to the bushing’s functional deterioration, upon removal of the bushing the crew reported oil ran out of it when they laid it down inside a crate. The crew further reported that when they proceeded to drain and dispose of the bushing, water and oil came out of it. The utility crew suspects the top seal must have been leaking and taking in moisture.
The Results
This success story highlights that an investment in online continuous transformer and bushing monitoring was critically required to identify an impending failure, validated by offline testing. For transformers where the critically of service and uptime are paramount, online transformer and bushing monitoring is warranted and economically justified.
Economically, it is estimated, that had the bushing run to total failure, the transformer’s replacement cost would have exceeded $2.0 Million US dollars. Additional and immeasurable expenses would have occurred, not limited to: the cost of customer service (outages), replacement power, the impact on national security, economic disruption, safety and the environment. The reliability and accuracy of the Dynamic Ratings bushing sensors, monitor, analytics, alarming and communications as a solutions system was validated by an offline test.
Dynamic Ratings solutions enable utilities and industrial to increase:
- Reliability: through early failure detection.
- Maintenance Savings: through advanced analytics, and DynamicMetrix™ software & data visualization solutions that filter through condition data to identify and notify of issues requiring maintenance attention.
- True Electric Equipment Capacity Realization: online, continuous monitoring of operational parameters allows the Dynamic Rating of electrical equipment for optimal performance realization.