This project will apply vacuum interrupter technology to develop a method for switching both ac and dc currents up to 200,000 Amp at voltages up to 1000 Volts. Switching with vacuum interrupters is widely used in electric power distribution systems and is the most advanced technology available today. This project will address specific issues related to using the existing technology in applications where higher interrupting currents but lower voltages are required. The advantages of the proposed method are: 1. use and expansion of proven, existing and commercially attractive technology; 2. low cost of vacuum interrupters; 3. low weight; 4. stable operation of the vacuum arc; 5. long life; 6. minimal losses in closed position at high load currents; 7. virtually maintenance-free interrupters; 8. possibility of diverting undesirable stray magnetic fields inside the interrupter to enhance the current interruption capability.