INSS Panel “P” Arc Flash Reductions

Project Description

Chugach Electric Association (Chugach) is the largest electric utility in Alaska and is headquartered in Anchorage, AK. The Panel “P” Arc Flash Reductions project was located at the International Substation (INSS), south of the Chugach main office building. The substation operates at 34.5kV and has two black start turbine generators. Panel “P” was the de facto Main Distribution Panelboard (MDP) providing 480V power to the substation and had an unacceptably high arc flash value. To increase worker safety, Chugach hired Taku Engineering to assess the system and design improvements.

INSS Panel “P” Arc Flash Reductions

What we did

Taku Engineering used the EasyPower software platform to model a new electrical system. EasyPower is an industry leading software platform used to model electrical systems to perform various electrical studies (e.g. arc flash, short circuit coordination, system stability, etc.). A new site distribution system was designed that focused on worker safety and arc flash reductions.

The new site distribution system used a new 2,500A, 480V Main Distribution Panelboard (MDP) located in the compressor building. The MDP is served by a new 12.5kV/480V, 1.5 MVA power transformer fed from a new 12.5kV circuit via a spare 15kV fused switch. The new power transformer and MDP were sized to provide 480V power for existing site loads with spare capacity for future loads. The 480V power provided to the new MDP is metered upstream of the MDP main circuit breaker.

The design was completed in 2018 and the installation was completed in early 2019. Taku Engineering provided the following services:

  • Electrical Engineering
  • Electrical Studies
  • Total Installed Cost (TIC) Estimating
  • Construction Administration Services
  • As-built Services

Final Results

The new equipment locations, equipment configuration, and equipment settings were carefully selected with the goal of achieving better worker safety. Using modern fast acting molded case breakers, current limiting fuses, and physical separations, the new design limited the short circuit capacity at the main distribution panelboard and reduced the arc flash values to safe levels.This project was delivered as designed, on-time, and on-budget.

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