isolated phase bus

Isolated Phase Bus

Safe, reliable isolated phase bus systems for medium voltage demands in multiple generation applications

Innovative isolated phase bus duct systems to meet global demands

Around the world, Avail’s medium voltage isolated phase bus duct systems are deployed in a wide range of critical applications that require the highest degree of reliability. For decades, plants and facilities have relied on Avail’s expertise in custom-designed solutions to deliver unmatched performance in iso phase bus ducts.

Avail isolated phase bus systems, used as generator main leads extending to GSU transformers and excitation service/auxiliary transformers, offer a cost-effective, fully integrated solution for multiple applications, including hydro plants, nuclear power stations, combined cycle power plants, fossil plants, and renewable plants. 

The advantages of a value-based iso phase bus duct partner

As a single-source provider, Avail offers cost efficiency not available with other isolated phase bus system suppliers. Our welded in-plant elbows and t-taps are easier to install, reducing field costs. Additionally, our extensive shipping capabilities, including transporting 40-foot sections with all three phases on a single skid, further reduce field costs.

isolated phase bus

1. Generator termination, 2. Potential transformer/surge arrester cubicle, 3. Generator circuit breaker connection, 4. Firewall and generator tie connection, 5. GSU transformer connection

Engineered for optimal performance in isolated phase bus systems

With Avail’s advanced design, each phase in our isolated bus duct is mounted in individual enclosures. The conductors are air insulated and supported in the center phase enclosures by strategically arranged insulators. This safer approach ensures maximum system integrity by eliminating phase-to-phase short circuits. Our insulated saddle supports prevent current induction in steelwork, cables, pipes, or other metal structures. Avail can design and install the entire isolated phase bus system, including interfaces with major manufacturers of generators, generator circuit breakers, and transformers.


  • Current: 600–25,000 (air-cooled), up to 50,000 amps (forced-air cooled)
  • Voltage: 15kV–38kV
  • Insulation levels: 110–200kV (BIL)
  • Momentary current: Up to 1,000,000+ Amps Asymmetrical
  • Standards: Meets or exceeds ANSI/IEEE and IEC Standards

Choose Avail for your isolated phase bus duct to experience innovative solutions that provide superior reliability and performance in medium voltage applications.

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