Overvoltage protection apparatus having fusible ring and short circuit means operated thereby

Claim 2

An overvoltage protection apparatus in which the improvement comprises: an overvoltage protection device including a sealed envelope and a plurality of electrodes supported in spaced insulated relationship to provide a spark gap within said envelope; and an external fusible ring of metal having a lower melting temperature than said electrodes, said fusible ring being mounted on said device in a position external to said envelope with said ring surrounding and in contact with one of said electrodes.

Claim 3

Apparatus in accordance with claim 1 in which a pair of sleeves of plastic material are provided over the envelope of said device on opposite sides of the fusible ring.

Claim 4

Apparatus in accordance with claim 2 in which said one electrode is an intermediate electrode positioned between two end electrodes and a pair of terminal members are provided over the outer ends of said sleeves and are connected to said end electrodes by connectors.

Claim 5

Apparatus in accordance with claim 3 in which said connectors are separate members extending through openings in said sleeves and into cavities formed in said terminal members and said end electrodes.

Claim 6

Apparatus in accordance with claim 4 in which the connectors engage the walls of said cavity for releasably Connecting the terminal members to the other electrodes.

Claim 7

Apparatus in accordance with claim 1 including a base member of insulating material having thereon a plurality of spaced insulated electrical contacts including a pair of signal contacts which are releasably connected to a pair of end electrodes on opposite sides of said one electrode of said device, and a movable ground contact means engaging said fusible ring for grounding said one electrode and normally spacing said ground contact means away from said end electrodes in an open circuit position, and for moving said ground contact means upon melting of said ring, from said open circuit position into a short circuit position relative to said end electrodes to short circuit them together.

Claim 8

Apparatus in accordance with claim 6 in which the ground contact means includes a pair of movable contacts on opposite sides of said overvoltage protection device, and spring bias means for resiliently urging said movable contacts together into engagement with said ring to connect said one electrode to ground and to releasably mount said device on said base member.

Claim 9

Apparatus in accordance with claim 7 in which the movable contacts are of a cross shape with the arms of said cross being resiliently urged by said spring means into engagement with said terminal members when said ring melts.

Claim 10

Apparatus in accordance with claim 6 in which the overvoltage protection device is secured within a hollow holder means of insulating material for insertion and removal of said device into and out of engagement with said contacts by movement of said holder means.

Claim 11

Apparatus in accordance with claim 9 in which a cover member is releasably attached to said base member to form a housing containing said device and said holder means.