Avoiding Failure, Extending Life of System-Critical Electrical Bus Ducts

BY MOHSEN TARASSOLY

Over the course of the past year, many power plants have shortened, postponed or rescheduled their maintenance outages due to the pandemic. Unfortunately, this has caused some critical maintenance activities to be put on the backburner. For many in the power generation industry, this has presented some uncertainties as the volume of unplanned outages caused by deferred maintenance is expected to rise.

One component that is often overlooked as being system-critical is the electrical bus duct system. The bus system is a plant’s main vessel of power distribution, carrying large amperage currents from the generator to a step-up transformer. In other words, the bus system acts like a giant extension cord. Although the value of the electrical bus duct system may seem minimal when compared to that of the generator or the transformer, the bus duct system plays a vital role in the plant. Consider it the lifeline between both high-value components; if a failure occurs, there is a good chance the connected appendices will be impacted. Electrical bus duct systems do not have redundancy. Being custom-designed components for each plant, they also do not have a quick-fix or replacement solution readily available.

To make matters worse, the pandemic has broadly impacted the global supply chain, introducing significantly longer lead times, especially for systems that have obsolete or difficult-to-procure replacement components. As such, the need for having an ironclad contingency and a proactive, preventative maintenance plan has never been more prevalent. Nevertheless, a growing number of plants have adapted a run-to-failure strategy, known as reactive maintenance. Although this strategy can cost less in the present, waiting until something fails is a big gamble. It is a risk that can significantly lower efficiency and further contribute to bottom-line profit losses if an unplanned outage or catastrophic failure occurs. In fact, studies have shown that running to failure costs an average of four times more than implementing a routine proactive, preventative maintenance schedule.

Industry best practice recommends bus duct maintenance yearly, at every scheduled plant outage, or at a minimum of every 18 to 24 months. However, over the past few years, online monitoring options have exploded in the marketplace, adding to the misconception that offline inspection maintenance can be postponed. Generally speaking, these diagnostic reports only provide provisional or nondefinitive findings that cannot be confirmed unless an offline inspection is performed. So, you are spreading your budget across two activities with partial results, versus one that provides certain results (offline inspection).

Leading utilities are partnering with highly experienced and trained bus duct experts and relying on them to proactively manage these critical assets on their behalf. This approach results in less down time, increased operational efficiency and safety, and is the key in preventing a bus duct failure.

A thorough offline inspection can identify, with certainty, many things, including but not limited to poor installation or system design; cracked insulators; localized overheating; corona/arcing; condensation and water intrusion; loose connections; loose, missing, or inappropriate hardware; dust and dirt build up; debris and foreign material; improper grounding; cracked weld joints; poor or inadequate insulation, lack of proper silver plating, and more. Once these abnormalities are discovered, proper repairs or upgrades can be performed to ensure the system is running in optimal condition. Routine preventative maintenance is not only a cost-effective way to extend the life of your electrical assets, but also a critical task in minimizing the risk of a forced outage and bodily harm to on-site personnel.

In conclusion, incorporating a proactive, preventative maintenance program for electrical bus duct systems can increase operational efficiency, production and safety.

Author: Mohsen Tarassoly Sales Engineer Director, Electrical Builders Inc. mtarassoly@electricalbuilders.com www.electricalbuilders.com