July 27, 2001

First Trans-Rupter II^® Model SE Installation Saves Time and Money.

The first Trans-Rupter II Tranformer Protector Model SE was recently installed at a municipal utility in the United States’ Great Lakes region. As part of a major substation upgrade, the utility replaced an existing transformer with a new 15-MVA transformer. 69-kV power fuses had previously been used for transformer protection, but with the new transformer, the utility wanted to upgrade to a device with more sophisticated protection capabilities. They evaluated circuit-switchers for the application, but the required relaying and control power would have raised the installed cost significantly and the circuit-switcher’s capabilities were beyond what they needed for the application.

The Trans-Rupter II Model SE proved a perfect match for their needs. Trans-Rupter II provides three-phase protection, a fast 3-cycle interrupting time, and a 31.5-kA fault-interrupting rating — more than enough for the system requirements. The Model SE’s overcurrent protection system offered a complete protection solution. It includes three single-phase self-powered overcurrent relays for comprehensive overcurrent protection, along with a trip-energy supply that provides the energy needed to trip all three pole-units. Substation batteries were not needed to power the overcurrent relays or pole-units.

Installation of the device was a quick and simple procedure. An S&C Mounting Pedestal — which includes wired conduit, cut to length, to connect pole-units to the control cabinet — was furnished, dramatically reducing the total installation time. It took three crew members only 3½ hours to both install the pole-units and relay control cabinet on the mounting pedestals, and also to make the wiring connections between pole-units and the control cabinet.

Within the first few days after installation, the Trans-Rupter II was called on twice to operate as the utility completed work on the substation. In one instance, wiring for other control devices in the substation caught on fire, necessitating a quick operation. In the second event, a potential transformer failed and created a fault — again necessitating a Trans-Rupter II operation. In both cases, the Trans-Rupter II performed exactly as expected, sparing the utility possible damage to the new transformer and other substation equipment.