Voltage monitor for alternating current power system
CA 2100652 C · Owner: Schweitzer, Edmund O. Jr. · Inventors: Schweitzer, Edmund O. Jr.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A voltage monitoring device for an AC power distribution system utilizes a liquid crystal optical shutter device capacitively coupled between a conductor of the system and electrical ground such that the transparency of the optical shutter device to light varies with the system voltage level. A light source projects a light beam through the optical shutter device to a light detector such that the output of the light detector is dependent on the system voltage. A control circuit responsive to the output of the light detector provides an output signal when the system voltage falls outside of a predetermined operating range.
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 July 15, 1993 and granted April 11, 2000. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended July 15, 2013.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by July 15, 2015.
- 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.