June 11, 2001

Watch the Checkout of a Trans-Rupter II^® Transformer Protector.

A 115-kV Trans-Rupter II Model EX was installed last year at a substation in the Pacific Northwest, replacing a Mark V Circuit Switcher. The customer had experienced significant growth in available fault current — beyond the fault-interrupting rating of the Circuit-Switcher. The Trans-Rupter II’s 31.5-kA fault-interrupting rating is more than sufficient for the customer’s requirements.

In this application, the 115-kV line loops through the substation, with motor-operated vertical-break switches on the incoming line (shown in the figure below). A V-type disconnect switch is used to split the high-side bus, and V-type disconnect switches are on the line side of the transformer-protective devices to provide visible air-gap isolation. (An S&C Series 2000 Circuit-Switcher Model 2010 protects the second transformer.)

During checkout of the Trans-Rupter II, the switches designated MOAB 1, MOAB 2, VSW 1, and VSW 2 were closed, and VSW 3 was open (the Trans-Rupter II was isolated). MOAB 2 was then opened, splitting the 115-kV loop. Next, VSW 2 was opened, splitting the high-side bus in the substation, and VSW 3 was closed. MOAB 2 was then closed, energizing the Trans-Rupter II and the transformer it protects. The Trans-Rupter II was subsequently tripped, interrupting transformer magnetizing current to drop the transformer.

Next, Switch VSW 3 was opened, dropping the cable between the switch and the Trans-Rupter II. Watch the video of VSW 3 being opened. (800k MPEG File) The Trans-Rupter II pole-units were then closed and charged.

VSW 3 was then closed to pick up transformer magnetizing current. Watch the video of VSW 3 being closed. (800k MPEG File) The utility left the transformer in this energized state until the next day, when load switching was performed on the low side. The Trans-Rupter II has remained in service since then and has performed reliably.