Solid Blade Switch Testing
A solid blade switch (also called a by-pass switch, or switch-disconnector) is a common, relatively inexpensive switching device applied to backbone feeders to pick up and drop load. Under regular day-to-day switching up to 900 amps of load may dropped or picked up. Many utilities use 600 and 900 amp, solid blade switches on their systems to isolate faults and minimize the number of customer outages on radial distribution feeders. Isolation is done after an upstream protective device de-energizes the feeder because these devices are not designed to open and close under fault current. While there is confidence that solid blade switches have been designed and dimensioned to operate adequately under normal duty, closing into a fault is not an operation for which this equipment is designed. Therefore, testing the equipment for operation under such duty is advisable. The purpose of this project is to ensure that solid blade switches can be safely operated under test conditions designed to replicate closing into a fault.