Isolated Phase Bus Project

Quillota, Chile

A transformer malfunction caused fire and damage to the existing GSU and the isolated phase bus duct connections at a power plant in Chile. Our team was called in to assess the damage, recommend actions and make repairs in order to return the plant to working order.

When our team arrived in Chile, we took note of the plant’s current condition. The GSU transformer was a complete loss. Additionally, the team found that the conductor of the existing isophase bus was octagon shaped with a 3-insulator design. As the new bus would be a round conductor, plates would need to be provided to join the two different types. Luckily, there were no signs of damage from the first set of insulators.

Our team faced quite the challenge with the site. First, it was very remote. It required at least a 10+ hour flight from the United States, and after the 2 hour drive to the site, jet lag became a concern. In order to ensure safety, this second day was a travel day for the team. The job was done in July, which in Chile means temperatures ranging from 40 degrees to 60 degrees.

The goal was to place a temporary transformer beyond the existing GSU firewall. We retrofit a new isolated phase bus duct from the existing isophase to the temporary transformer. Incorporated in the design for this duct was an option that would allow for easy modification at a later date.

In order to achieve this, the existing bus was cut on the inside of the blast wall toward the existing GSU and the new bus was retrofitted from the existing bus extending approximately 13.5 meters to the temporary transformer. Our team coordinated the shipping of the new isophase bus and recommended the new bus contain a tap that is capped which will drop to the new replacement transformer for ease of installation to the new replacement transformer. At a later date the newly installed bus will be cut and capped upon removal of the temporary transformer.

The project was completed in a time-frame of 2 weeks and the plant was returned to working order.