EBI sent their crew and equipment to this Florida power plant to perform emergent inspection and cleaning of the Isolated Phase Bus (IPB) and to determine the cause of the excessive water/moisture intrusion. EBI’s scope included:
- Cryogenic cleaning
- Painting of the conductors
- Unplugging the drain holes and replacing with plant supplied drains
- Re-silver plating the contact surfaces
- Removal and replacement of the AUX conductor end (due to extreme pitting)
- Installing new braided flex links
- Replacing the existing hardware with new appropriate type
EBI performed a final IPB bus duct acceptance DC Hi-Pot test per IEEE standards, cleaned their work area and demobilized all crew and equipment.
Water intrusion and condensation are common isophase bus duct system issues uncovered by EBI quite frequently. Outdoor bus systems that are subject to drastic temperature fluctuations (thermal cycling), have recently been de-energization/re-energization due to an outage, and systems that are not properly sealed are a few common indicators that an underlying condensation issue may be present. Heaters, dry air pressurization systems, drainage systems, and desiccant dryers are just a few examples of ancillary enhancements that can be installed aftermarket on existing systems to combat condensation that can form in isophase bus systems.