Fast acting disconnect system for protecting surge suppressors and connected utilization equipment from power line overvoltages

In an electrical disconnect system for protecting a transient voltage surge suppressor from power frequency overvoltages and also for protecting a load comprising utilization equipment connected thereto from said power frequency overvoltages, said system including input terminals for connection to a source of AC voltage, and output terminals for connection to said utilization equipment, surge suppressor components connected to said input terminals for clamping short duration transient voltage surges to a safe value, said surge suppressor components and said utilization equipment being capable of enduring said power frequency overvoltage for a brief period of time without damage, said system comprising:

• an electrically operated switch having AC source connection terminals for connection to said source of AC voltage and load connection terminals connected to said input terminals, a resettable disconnect switch for connecting and disconnecting said AC source connection terminals from said load connection terminals, a switch operating mechanism for opening said disconnect switch when energized, to disconnect said AC source connection terminals from said load connection terminals, and a latch mechanism for resetting said disconnect switch for reconnecting said AC source connection terminals to said load terminals;
• and
• a sense and control circuit for rapidly energizing said switch operating mechanism upon a power frequency overvoltage at said input terminals, said sense and control circuit including a capacitor and a capacitor charge circuit therefor for charging said capacitor directly from said input terminals to a disconnect switch operating voltage level which energizes said switch operating mechanism to open said disconnect switch, and a capacitor discharge switch connected between said capacitor and said switch operating mechanism to couple thereto the voltage charge on the capacitor when it reaches said disconnect switch operating voltage level,
• whereby said disconnect switch disconnects said input terminals from the AC source connection terminals before the end of said brief time period during which said surge suppressor components and said utilization equipment can endure said power frequency overvoltage without damage, thereby protecting both the surge suppressor and the utilization equipment from said power frequency overvoltage.