Overload protected solid state varistors
AssigneeMaida Development Company
InventorsJohn C. Bennett, Ronald D. Boyd, Robert W. Stockum
Life of this patent
Estimating the term…
Abstract
A fail-safe varistor includes either a fail-short or a fail-open device. Both devices include a fusible, electrically conductive material that melts before the varistor fails due to overvoltage. In the fail-open device, the fusible, electrically conductive material joins separated portions of the leads. The material also may join at least one of the leads directly to a ceramic disk of the varistor. Upon reaching the predetermined temperature, the varistor melts causing a circuit including the varistor to open. In the fail-short device, the material melts creating a short between the leads. This short causes a fuse or a breaker to open the circuit.
Claims11
A solid state varistor having thermal overload protection, comprising:
- a metal oxide varistor;
- and
- leads connected to the semiconductor device, at least one of the leads having a fusible link between separated portions of the at least one lead, the fusible link being meltable when heated to a predetermined temperature creating an open circuit between the separated portions, and
- a heat sensitive elastic member formed around the fusible link to further separate the separated portions as the fusible link melts.
A solid state varistor having thermal overload protection, comprising:
- a metal oxide varistor having first and second surfaces;
- a first lead electrically connected to the first surface;
- a fusible link electrically connected to said second surface;
- and
- a second lead electrically connected to said second surface through said fusible link, said fusible link being enclosed in a containment material such that as said fusible link melts within said containment material, an open circuit is formed between said second lead and said second surface.
A solid state varistor having thermal overload protection, comprising:
- a metal oxide varistor;
- and
- leads connected to the metal oxide varistor, at least one of the leads having a proximal portion and a distal portion, the proximal portion having a proximal straight portion and a proximal bend portion, the distal portion having a distal straight portion and a distal bend portion, the proximal bend portion and the distal bend portion being electrically connected by a fusible link, the fusible link being meltable as heated to a predetermined temperature creating an open circuit between the proximal bend portion and the distal bend portion.
Dependencies are inferred from the claim text.