We manufacture compressed gas insulated transmission bus systems, type CGIT (also known as GIL) which provide a compact, reliable and economical alternative to conventional cable systems and overhead lines for power transmission. Our major customers include electrical utilities, independent power producers and design/construction firms.
The effective electrical and magnetic shielding afforded through the CGIT design allows for minimized right-of-way requirements as well as safer environmental conditions. Standard CGIT systems are suitable for voltages from 115kV to 1200kV with current ratings as high as 6000 amperes.
Company Background
CGIT (Compressed Gas Insulated Transmission) Bus Systems have been in use worldwide since 1972. First developed by High Voltage Power Corporation in cooperation with the Massachusetts Institute of Technology, MIT, the product line was purchased by the Westinghouse Electric Co. in 1974. Westinghouse continued its manufacturing and development until the CGIT business was purchased by ABB Power T&D in 1989. ABB continued manufacturing CGIT bus as an extension of its GIS Products until 1999, when AZZ incorporated purchased the product line. CGIT remains a world leader in the supply of long distance transmission bus, for GIS projects as well as for standalone gas insulated bus applications.
Currently we have over 75km installed worldwide.
Some of our major customers include:
| • BC Hydro |
| • Consolidated Edison |
| • Enron Power |
| • Entergy |
| • Ontario Hydro |
| • SCECO |
| • Southern California E |
Product Background
The first commercial CGIT system was installed in 1972. Since then, more than 46 miles (75km) of CGIT have been delivered and installed worldwide. Simple and inexpensive interfaces exist to many types of high-voltage equipment including GIS, transformers, oil paper cables, and SF6-air bushings. The vast design capabilities of the CGIT system has been utilized in many unconventional applications in addition to standard transmission paths. The CGIT system can be installed in the following ways:
| • At ground level |
| • Elevated above ground |
| • Below grade in an open or covered trench |
| • Directly buried underground |
| • Vertically in tunnels, shafts or towers |
| • Suspended from existing substation structures |
Economic advantages
The low costs of installation, operation, and maintenance are common to CGIT systems. CGIT installations consist of a number of sections, each terminating in plug/socket joints, which are pre-established prior to arrival to site. Type HM contact assemblies provide the high current conductor connections which continue the low loss electrical paths of the system. The lower losses within the CGIT circuits equate to lower operating costs. Once installed, maintenance of the system can be reduced to annual SF6 gas moisture and pressure checks, and mechanical assembly checks (i.e. bus exterior, supports, etc.). Since the CGIT system includes no active or switching components that may wear during use, it is never intended that the system be opened for inspection or maintenance.
Further advantages of the Compressed Gas Insulated Transmission System Type CGIT are:
| • No auxiliary pumping or cooling equipment |
| • No fire hazard |
| • The safety of dead-front, grounded, construction |
| • Long life with high reliability |
| • No radio noise interference |
| • No appreciable external magnetic fields |
| • Very low dielectric losses |
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