Patents Assigned to Yelland Engineering (Proprietary) Ltd.
  • Patent number: 4494163
    Abstract: An electric switching surge protector comprising a non-linear, voltage and frequency sensitive RC network connectable between earth and a phase of a switch controlled, AC electric load circuit. The RE network includes a linear resistance component; a non-linear resistance component connected in parallel with the linear resistance component and having a pre-determined knee-point voltage value; and a capacitance component connected in series with the parallel connected linear and non-linear resistance components. The capacitance component is operative to decouple the resistance components from the circuit at power supply frequency but to couple the combined resistive impedance of the parallel connected linear and non-linear resistance components effectively into the circuit under high frequency conditions. The capacitance component is further operative to increase the rise time of that portion of a steep fronted surge which exceeds the knee-point voltage value of the non-linear resistance component.
    Type: Grant
    Filed: August 2, 1982
    Date of Patent: January 15, 1985
    Assignee: Yelland Engineering (Proprietary) Ltd.
    Inventors: Christopher P. Yelland, Rapha E. Pretorius