Power supply for cathodic protection system
OwnerGary Marson, Art W. Gaberinventors
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Abstract
A power module for a cathodic protection system is provided having a switch-mode power circuit and a synchronous switch assembly. The method of the invention comprises rectifying an alternating utility power signal with a power transformer and switch assembly. The switch assembly is controlled by a phase control circuit to provide a selective controlled phase delay to provide a 0-100% range power signal to the load selectively operable in a constant current, constant voltage or off-potential manner.
Claims14
An assembly for cathodically protecting a structure by impressing a selective electrical potential upon the structure with high frequency switching, said impressing being selectively operable in either a constant current, a constant voltage, or an auto-potential mode, said assembly comprising:
- a source of an alternating voltage power signal;
- a switch mode power circuit means for generating a square wave voltage form the source;
- a power transformer having a primary side winding and a secondary side winding, the primary side winding being driven by the power circuit means, the secondary side winding having a tap to divide the square wave voltage and produce a plurality of selectively phase differentiated square wave voltages;
- a switch means for selectively rectifying the phase differentiated square wave voltages;
- and,
- a phase control circuit means for selectively delaying the rectifying of the phase differentiated square wave voltages comprising means for delaying operation of the switch means proportionate to a frequency of the differentiated square wave voltages, wherein the switch means is delayed by a controlled phase delay time.
A method for selectively adjusting the energy impressed on a structure by a cathodic protection system comprising the steps of:
- rectifying a conventionally available energy signal with a high frequency switch-mode power circuit and a synchronous detector switch assembly;
- impressing the rectified signal on the structure;
- measuring a parameter representative of the impressed energy and generating a control signal representative of a difference with the measured energy and a desired energy;
- and,
- adjusting a timing operation of the switch assembly to selectively adjust the rectified signal whereby the adjusted rectified signal substantially impresses the desired energy on the structure.
An off-potential method for selectively adjusting the energy impressed on a structure by a cathodic protection system having a high frequency switch mode power circuit and a synchronous detector switch assembly comprising the steps of:
- supplying an energy signal to the structure;
- selectively halting the supply of energy for a preselected period of time including switching the energy signal to obtain opposite phased signals and adding the signals to produce a zero signal;
- measuring the potential difference between the structure and a reference cell during the preselected period, the measuring being substantially I-R drop free;
- comparing the measured potential difference with a preselected desired potential level;
- and,
- adjusting the supplied energy in a preselected manner.
Dependencies are inferred from the claim text.