April 8, 2002

Trans-Rupter II^® Retrofit Kit Saved Cooperative Thousands of Dollars on Circuit-Switcher Upgrade.

As a part of a maintenance and equipment upgrade program, a rural electric cooperative in Utah decided to upgrade an over 30-year-old S&C Mark II Circuit-Switcher protecting a 138-kV power transformer. As a cooperative with a limited budget, cost would be a major consideration in their selection of new equipment. The cooperative wanted to find the most cost-effective way to upgrade the aging Circuit-Switcher, while preserving the performance and ease of use they’ve enjoyed with their existing Mark II Circuit-Switcher for over three decades.

After examining their options, they decided to purchase a Trans-Rupter II Transformer Protector retrofit kit. In these retrofit packages, the Trans-Rupter II pole-units mount directly to the Circuit-Switcher bases and provide enhanced transformer protection. The blade assemblies of the Circuit-Switcher are retained to provide a source-side series disconnect. Retrofit kits include all mounting brackets and hardware needed to complete the installation. Retrofit kits can also be ordered with optional motor operators. The installation crew used a bucket truck to remove the Mark II interrupters and to hoist the Trans-Rupter II pole-units into place on the existing structure eliminating the expense of renting heavy-hauling equipment. The pole-units were easily attached to the Mark II bases using special mounting brackets. No modifications to the structure or the existing foundations were required, saving installation time and money. The customer also reused their existing control power source, relays, and associated wiring, eliminating the expense of new wire runs and additional trenching.

The Mark II blade assembly was retained to provide an integral source-side series disconnect. The new Trans-Rupter II retrofit kit provided an increased fault-interrupting capability of 31.5-kA and a faster 3-cycle interrupting time. And by retaining the existing Mark-series blade assembly and Circuit-Switcher operator, the fault-closing rating of the original Circuit-Switcher was maintained.

The cooperative saved thousands of dollars in materials and labor by purchasing the Trans-Rupter II retrofit kit, and plans to purchase additional retrofits kits within the next few years, as their equipment upgrade program progresses.