Ground fault detector
CA 2025014 C · Owner: Fujitsu Limited · Inventors: Tojo, Toshiro; Takato, Kenji; Kinoshita, Kazumi
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
In a ground fault detector for long distance subscriber lines accommodated in a small capacity digital electronic exchange, a DC/DC converter for power supply is stopped during detection of ground fault. Upon reception of the stop signal, the DC/DC converter converts the power supply voltage for the subscribers to a voltage as the system power supply of the exchange namely to a low voltage before voltage conversion of the DC/DC converter. The battery feed circuit can maintain the alarm condition, even if a current flows continuously to the battery feed resistor due to a ground fault, until the ground fault is re recovered by the maintenance person without breaking the resistor. - 15 -
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 January 12, 1990 and granted November 22, 1994. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended January 12, 2010.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by January 12, 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.