Arrester with external isolator
CA 2004444 C · Owner: Kershaw, Stanley S. · Inventors: Kershaw, Stanley S.; Veverka, Edward F.; Goedde, Gary L.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
An arrester for an under oil transformer is connected between a primary bushing lead and an insulator/isolator penetrating the wall of a housing which encloses the oil arrester, and transformer parts. A ground wire outside the housing is removably connected to the isolator which functions as a circuit disconnector. The ground wire is removed to open circuit the arrester so that the transformer may be tested without having to disable any parts in the housing. Responsive to an arrester failure the ground wire is blown, away to give a visual indication of the failure. The blowing away of the ground wire eliminates the need for the arrester to fail in an open circuit condition.
Read the whole patent
Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.
Why it's free to use
- Filed December 1, 1989 and granted June 30, 1998. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended December 1, 2009.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by December 1, 2011.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Timeline
Timeline From CIPO dates
Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.