Isolated Phase Bus Project

New Jersey

While performing an emergency bus duct repair, our team performed an inspection and cleaning of the isolated phase bus system. Part of this particular job required our team to open every bolted cover on the system, hand clean and replace the gaskets and bolting hardware.

Making sure to do our due diligence, our team inspected the integrity of the remaining bus duct to ensure there would be no additional concerns.  Once we removed the insulator access covers, we discovered that A, B, & C phases had a corroded, inoperable heater. For bus systems that are not in service full time or during times of an outage, functioning heaters are critical. Their function is to help raise the temperature of the insulators above the dew point to avoid condensation.  Furthermore, when the insulators are dirty, this condensation can lead to tracking, increasing the risk of complete failure. To fix the situation we encountered, our team replaced the heater and the wiring at all three of the insulator locations.

The remaining insulator access covers were removed, and the insulators, conductor and inside enclosure were all hand-cleaned with denatured alcohol and lint-free rags.  After a visual inspection satisfied our quality standards, the covers were reinstalled and with new gasket material and hardware.

Our team made maintenance recommendations to the generating station that select access covers on A, B, and C phase should be randomly opened at each and every planned outage, a visual inspection should be performed, and the gasket should be replaced on each cover opened.  If the condition of the bus system is unchanged, then the next random inspection should wait until the next planned outage when another set of covers should be selected to inspect further.