Intrinsically safe system
CA 2028028 A1 · Owner: Maltby, Frederick L. · Inventors: Houvig, Felix J.; Horrocks, Leslie D.; Maltby, Frederick L.
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A system for rendering intrinsically safe the electrical supply to field devices in a hazardous area includes redundant crowbar circuits coupled to the power supply which energizes the field devices and resistors in series with the electrical lines supplying the field devices. In this way, large numbers of field devices may be rendered intrinsically safe without use of expensive intrinsic safety barriers in each field circuit.
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 October 19, 1990. No grant is recorded for it in Canada; had it been granted, its 20-year term would have ended October 19, 2010.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by October 19, 2012.
- 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.