Zero voltage crossover detector for polyphase systems
CA 2004340 C · Owner: International Business Machines Corporation · Inventors: Shin, Charles H.; Woodworth, George K.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
Abstract, The invention finds application primarily in three phase power systems having A, B and C voltage phases. The invention includes a first voltage measurement device coupled between the A phase input and the B phase input having a first measured voltage output. The invention further includes a second voltage measurement device coupled between the A phase input and the C phase input having a second measured voltage output. The invention also includes a comparator having a first input connected to the first output of the first voltage measurement device and a second input connected to the second output of the second voltage measurement device for generating, a signal when the first …
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 November 30, 1989 and granted October 26, 1993. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended November 30, 2009.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by November 30, 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.