Electrical Distribution

Non-segregated phase bus runs are designed for use on circuits whose importance requires greater reliability than power cables provide. Typical of such applications are the connections from transformers to switchgear assemblies in unit substations, connections from switchgear assemblies to rotating apparatus, and tie connections between switchgear assemblies. Non-segregated phase bus is an assembly of bus conductors with associated connections, joints, and insulating supports confined within a metal enclosure without interphase barriers. The conductors are adequately separated and insulated from each other and ground by insulating bus supports. Each conductor for 2400V service and above is insulated with a fluidized bed epoxy coating throughout which reduces the possibility of corona and electrical tracking.

Features, Benefits and Functions

Ease of Installation
Because of its compact dimensions, relative light weight, and user-friendly design, non-segregated phase bus is easily installed. The inherent rigidity of the design permits hanging rods to be spaced approximately every four feet for indoor bus runs, and allows supporting frames to be spaced approximately every eight feet for outdoor runs. Standard length of bus run sections is 100 inches (2540 mm) or less.

Short Circuit Force Withstand Ability
Non-Segregated phase bus runs in 600V, 5 kV, and 15 kV are designed to withstand three-phase and phase-to-ground short circuit current of 78 kA rms asym (132 kA peak) for 10 cycles and 50 kA rms sym for 2 seconds. Momentary 4-cycle withstand ratings up to 158 kA peak (98.8 kA rms asym) are also available. For 27 kV non-segregated phase bus runs, short circuit withstand ratings of 64 kA rms asym (108 kA peak) for 10 cycles and 40 kA rms sym for 2 seconds are standard.

Construction
Enclosures are fabricated from 11gauge steel, and are welded for maximum rigidity. Removable covers are secured with bolts for ease of access when making joints and subsequent and periodic inspection. (Aluminum housings are also available.) Enclosures are painted with a baked-on polyester powder coat paint system resulting in a very durable finish with uniform thickness and gloss. This cosmetically pleasing finish minimizes the risk of problems in harsh environments. The standard color is ANSI-61 light gray, and special paint colors are available upon request. Flexible joints are supplied in all straight bus runs at approximately 50 foot (15.2 m) intervals to allow for the expected expansion when the conductors are energized and are carrying rated current. A variety of terminations is available to accommodate most termination requirements. Bus runs can be terminated with flexible shunts, potheads, porcelain bushings, or conductor stub ends for connection to riser bars in switchgear assemblies.

Conductors
All conductors are 100% conductivity copper bars. Bus joints are made by solidly bolting the bus bars together with splice plates on each side. All joint surfaces are silver-plated to insure maximum conductivity through the joint. After bolting, each standard joint is covered by a preformed, flame retardant insulating boot, providing full insulation for bus conductors. These boots are easily removable for inspection of the joints at any future time.

Temperature Rise
The bus will be capable of carrying rated current continuously without exceeding a conductor temperature rise of 65?C above an outside ambient temperature of 40?C, as required by ANSI Standard C37.23.

Standards and Certifications
The metal-enclosed bus runs are designed for 600V, 5 kV, 15 kV, and 27 kV service in accordance with ANSI C37.23. 600V, 5 kV, and 15 kV bus is available with continuous current ratings of 1200, 2000, 3000, 3200 or 4000 amperes. 27 kV bus is available in 1200 and 2000 amperes continuous ratings.

Tests
The design of non-segregated bus runs has been tested per ANSI C37.23. Certification of momentary current testing, impulse testing, and heat runs are available upon request.

Seismic Application
Bus run assemblies are designed to meet Uniform Building Code (UBC) and California Code Title 24 for Seismic Zones 4, 3, 2A, 2B, 1, and 0. Complete guidelines for proper supports are provided on each Seismic specified order.