Improved variable frequency drive reflected wave suppressors
CA 2206409 C · Owner: Funke, James · Inventors: Tardiff, Dale; Funke, James
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
The invention provides a circuit to protect an AC motor powered by a Variable Frequency Drive (VFD) from overvoltages caused by reflected waves. A full wave bridge rectifier circuit across the lines of the motor to be protected provides rectified voltage output to a capacitor across which a low resistance, discharge resistor in series with one or more zener diodes is attached. When an overvoltage above the clamping voltage of the zener diode(s) occurs across the protected lines, the zener diode(s) will conduct causing the excess charge across, the capacitor to discharge through the resistor until the voltage drops below the clamping voltage of the diode(s).
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 May 28, 1997 and granted October 17, 2000. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended May 28, 2017.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by May 28, 2019.
- 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.