In the case of a retrofit to an existing gas insulated switchgear substation, the ability to design and install a variety of interfaces, and to allow sufficient installation tolerance is paramount. The existing equipment may include GIS supplied by different manufacturers who may adhere to contrasting philosophies and operating parameters.
In other retrofit cases, outdated equipment must be replaced. Again, the challenge remains to minimize the outage time required to implement the change and to utilize as much existing peripheral equipment at possible to reduce costs. CGIT (AZZ High Voltage Bus Systems) provides solutions to the problems faced when retrofitting or extending existing systems and offers turnkey installations and commissioning.
Project Profile: Consolidated Edison Dunwoodie Station (Yonkers, New York)
The Dunwoodie substation, commissioned in 1974, functioned well until 1988, when an oil cable fire destroyed a circuit breaker, the adjacent oil pot heads, interconnecting breaker bus and disconnects.
In rapid response to Consolidated Edison’s emergency requirements, CGIT provided interconnecting breaker bus to bypass the damaged breaker position and re-energize the ring. The CGIT bus left future expansion capabilities to interface to a new circuit breaker position that would be supplied at a later date. The interconnecting bus required interface to existing ITE bus. CGIT Systems was the only manufacturer that could respond to this emergency.
Seabrook Nuclear Power Plant Substation (Seabrook, New Hampshire)
The Seabrook gas insulated substation project, consisting of 345 kV ITE GIS and bus, had developed a history of unreliability due to leaks and insulator failures within the bus. This was particularly a cause of concern within areas of the substation that were not protected by redundant sections of the installation, thereby having no backup in case of section bus failures.
CGIT bus, backed by its established record of reliability in long-term service, was selected to replace the ITE bus for these critical connections. They involved connections from the GIS to both main transformers and to auxiliary transformers.
In addition to offering a reliable bus design, CGIT Systems defined and managed a schedule to complete the installation within a one-week outage to comply with the NRC approved outage schedule, and under tight space and access conditions.
The first of the Seabrook CGIT bus installations has been in service without fault since its completion in 1990.