Abstract: The present invention includes an anodic device for reducing corrosion adapted to reduce corrosion of an object subject to corrosion having a base with a thickness and surface area, and a plurality of protrusions protruding from the base each having a thickness and surface area, wherein the device is configured to allow a current to flow between the device and the object subject to corrosion. The present invention also includes methods associated with the use of such devices.

Abstract: Embodiments of a system and method for providing cathodic protection to a vessel include encapsulating a dimensionally stable anode with a wax-repellant cementitious coating. The anode, with the encapsulant, is inserted into a structure to be protected, such as a vessel for handling wet crude. A power supply is connected to the anode and to the vessel, making the vessel a cathode. When power is applied, ions flow from the anode, through the encapsulant and fluids in the vessel, to the vessel structure. The encapsulant prevents paraffin wax from building up on the anode.

Abstract: A multi purpose segmented Titanium Mixed Metal Oxide coated impressed current cathodic protection anode assembly (Ti MMO anode assembly). The Ti MMO anode assembly includes combinations selected from four anode components and four connection components. The various components may be assembled for different applications in liquid or soil environments for the prevention or reduction of corrosion and loss of structural integrity. For example, the Ti MMO anode assembly may be applied to protect pipelines, buried structures, piers and internal surface protection of tanks and vessels in different arrangements such as deep wells, shallow ground beds, or distributed individual anodes.

Abstract: An apparatus and method for monitoring cathodic protection of a protected object that includes a probe with five segments in series. The cathodic protection is provided by a system with a power supply that impresses current onto the protected object. An anode is included with the system that is also connected to the power supply. The third and fifth segments are in electrical communication through a frangible connection; that over time galvanically corrodes to electrically isolate the third and fifth segments. The second segment, which is a permanent isolator, is set between the first and third segments. The third segment is selectively connected with the protected object. When the third segment is selectively disconnected from the protected object, measuring the potential difference between the third segment and the first segment yields a value for object polarization that is void of IR error.

Abstract: A sacrificial anode system and associated surface pipe system maintenance method designed to protect surface pipes and associated parts. According to a first aspect of the present invention, the sacrificial anode system is installable at an interface between a first pipe and a second pipe and comprises an insertion sleeve shaped to fit along an inner surface of the first pipe, a flange attached to the insertion sleeve and shaped to rest against an end surface of the first pipe, a sacrificial anode to be positioned within the first pipe, and a stem linking the sacrificial anode to the insertion sleeve. According to a second aspect of the present invention, a method for maintaining a surface pipe system is also provided.

Abstract: An apparatus for providing electrochemical corrosion protection to a process vessel, the apparatus comprises at least one anode in communication with the process vessel; a DC current supply being electrically coupled to the process vessel and to the at least one anode; and a potential control unit in communication with the DC current supply. The potential control unit is electrically coupled to the process vessel and to a reference electrode in communication with the process vessel. The current supplied by the DC current supply for passivating the process vessel is adjustable by the potential control unit. The process vessel may comprise at least one of duplex stainless steel and superaustenitic stainless steel.

Abstract: The present disclosure is generally directed to devices and methods of treating aqueous solutions to help remove or otherwise reduce levels, concentrations or amounts of one or more contaminants. The present disclosure relates to an apparatus comprising spaced-apart electrode structural support members extending from a first sidewall to a second sidewall, the spaced-apart electrode structural support members each having at least one photoelectrode and counterelectrode coupled to respective terminals adapted to be electrically coupled to a power supply, and at least one ultraviolet light source between the spaced-apart electrode support members.

Abstract: A heat exchange system including a heat exchanger having a housing and a cooling core disposed within in the housing. The cooling core is adapted to receive a flow of a liquid cooling media. The heat exchanger includes at least one iron anode projecting into a flow path of the liquid cooling media. The heat exchange system also includes an electronic control module operatively connected to the iron anode. The electronic control module is adapted to control the selective delivery of electrical current or grounding to the iron anode in response to predetermined conditions indicating the presence of sulfide constituents in the cooling medium.

Abstract: A portable device includes a substrate, a number of electronic components, and a battery having an anode and a cathode for energizing at least some of the components. The application further relates to a method of protection a portable device against corrosion and to the use of a portable device. An object of the present application is to protect selected metallic parts of a bodyworn electronic device against corrosion in a flexible and controlled manner. The problem is solved in that the portable device includes a sacrificial anode in the form of a component adapted to be surface mounted on the substrate. This has the advantage that corrosion can be contained at a specific location. The device may e.g. be used for portable listening devices, e.g. hearing aids or headsets or earphones including a part adapted for being worn at or in an ear of a user.

Abstract: A package for fruits and vegetables having galvanic functionality is formed by using two or more metals with different galvanic activity properties on the surface of a nonmetallic substrate. The metals may be deposited electrolytically, by vacuum, autocatalytically, or by other methods. The metals are selected to create a galvanic reaction after the package is filled with a low pH food product and its associated liquids, juices, brine, etc. The package may extend the shelf-life of the food product contained therein, for example, by making metal ions available to the food product.

Abstract: The present disclosure is generally directed to devices and methods of treating aqueous solutions to help remove or otherwise reduce levels, concentrations or amounts of one or more contaminants. The present disclosure relates to an apparatus comprising spaced-apart electrode structural support members extending from a first sidewall to a second sidewall, the spaced-apart electrode structural support members each having at least one photoelectrode and counterelectrode coupled to respective terminals adapted to be electrically coupled to a power supply, and at least one ultraviolet light source between the spaced-apart electrode support members.

Abstract: A marine drive cathodic protection control circuit and method controls ohmic current from a power source to an anode according to electrical reference potential sensed by a reference electrode. The ohmic current is interrupted for an interruption interval, and reference potential is sensed during the interruption interval. The ohmic current is controlled according to reference potential sensed during the interruption interval.

Abstract: A system for detecting and preventing galvanic corrosion of an anodic metal includes a potential detector configured to monitor an electrical potential within the electrolyte solution, a signal amplifier coupled with the potential detector, and a current delivery circuit coupled with the signal amplifier. The signal amplifier is configured to provide an output proportional to the monitored electrical potential, and the current delivery circuit is configured to provide a current to a cathodic metal that is proportional to the output of the signal amplifier.

Abstract: A method is provided for corrosion protection in a marine construction, such as a marine surface vessel or a marine structure, the marine construction including at least one metal element and a sacrificial anode adapted to be at least partly immerged in an electrolyte in the form of water, in which the marine construction is at least partly immerged, the at least one metal element including a metal part, the sacrificial anode being provided for corrosion protection of the metal part. The method includes connecting at least one of the at least one metal element and the sacrificial anode to a DC electrical power outlet so as to allow an electric de-passivation current through an electrical circuit including the sacrificial anode, the metal element and the electrolyte.

Abstract: A method for corrosion protection in a marine construction including a plurality of metal elements and at least one reference electrode at least partly immerged in water, the metal elements including an anode and a metal part, the anode being provided for corrosion protection of the metal part includes measuring an electric potential of the metal part with the reference electrode as a ground reference. At least one of the metal elements and at least one of the at least one reference electrode are connected to a DC electrical power outlet so as to allow an electrical regeneration current through an electrical circuit including the at least one of the metal elements, the at least one of the at least one reference electrode and the electrolyte so that the reference electrode is anodized.

Abstract: Apparatus for connection to a metallic structure, the apparatus comprises a transformer rectifier unit operable to output a DC current for cathodic protection of a metallic structure, and a modulator unit connected to receive a DC output from the transformer rectifier unit. The modulator unit is arranged for connection to a metallic structure, and is operable to produce a modulated current which is applied to such a metallic structure when the apparatus is in use, such that the metallic structure is detectable by a wireless locating device. The modulator unit is operable to be controlled remotely.

Abstract: An electrolysis prevention device, for preventing corrosion caused by electrolysis, includes a sacrificial anode made of an active metal and an anode holder supporting the sacrificial anode. The holder is adapted to fit around the inlet connection of an engine heat exchange component, such as a radiator or heater core, in such a way as to allow for a hose to be attached overtop the device. The device may be included in an originally-manufactured engine heat exchange component or may be installed later.

Abstract: A method in a corrosion protection system for protecting a first and a second metal part of a marine construction is provided. The method includes controlling electrical currents through electrical circuits, including respective anodes, the respective metal parts and an electrolyte, at least partly based on measured electrical potentials of the respective metal parts with an reference electrode as a ground reference. The method further includes repetitively performing the steps of controlling the electrical currents so as to be reduced or eliminated, measuring the electrical potentials while the electrical currents are maintained reduced or eliminated, and, after measuring the first and second electrical potentials, controlling the electrical currents so as to be increased or reestablished.

Abstract: A method for inhibiting corrosion in at least one required region of an elongate metal structure, comprising applying a high-frequency electromagnetic signal to the structure in a manner such that a voltage standing wave is established in the structure with a corrosion-inhibiting potential at the required region(s) of the structure. The method is advantageously applied to an oil well riser pipe, to inhibit corrosion of the external surface thereof in the vicinity of an oil production zone.

Abstract: Techniques generally describe articles of enclosing manufacture and methods related to containers including a magnesium sacrificial anode for corrosion protection. Example articles of enclosing manufacture may include a liner or a rod that is configured as a sacrificial anode to protect a metallic side or end wall of the enclosing manufacture from corrosion. Other embodiments may be disclosed and claimed.

Abstract: This invention relates to protection of a metal component exposed to a corroding medium. One or more of the following are provided: cathodic protection, measuring of a condition of the component, retarding or avoiding of fouling. A sacrificial anode is used as the energy source such that the electric circuit can provide a pulsating current, voltage, automatically adapted current, or protecting potential. Germanium solid state elements are used.

Abstract: A method and system for protecting underground gas carrier pipes housed within an outer casing pipe in which a gas carrier pipe section disposed within an outer casing pipe section and having opposed ends is electrically isolated from a remaining gas carrier pipe section proximate each of the ends. An annular space between the gas carrier pipe section and the outer casing pipe section is filled with an electrolyte. At least one anode electrode is inserted into the annular space distal from each of the gas carrier pipe section and the outer casing pipe section and connected with a positive voltage lead of a cathodic protection rectifier. A negative voltage lead of the cathodic protection rectifier is connected to the gas carrier pipe section.

Abstract: Techniques are generally described herein for protecting food or beverage containers (e.g., cans) using impressed current protection. In various embodiments, containers may be received into at least one conductive bed, each bed having a complementary anode. The containers may then be electrically coupled to a first terminal (e.g., negative) of a power supply, and the anode may be electrically coupled to a second terminal (e.g., positive) of the power supply. Resultantly, protective current may be provided to the containers by the anode. Other embodiments may be disclosed and claimed.

Abstract: The invention is a process for cathodic protection of electrodes wherein negative bias is applied on the electrode. The negative bias is obtained by asymmetric current pulse, which is obtained by negative phase pulsing with higher amplitude than that of the anodic phase. The asymmetric current pulse is obtained by negative phase pulsing with wider pulse width than that of the anodic phase. The asymmetric current pulse may also be obtained by negative phase pulsing with both higher amplitude and wider pulse width than that of the anodic phase. The invention further relates to a process for cathodic protection of electrodes, wherein negative bias is applied on the electrode, and the negative bias is obtained by asymmetric current pulse, where the asymmetric current pulse is obtained by negative phase pulsing with wider pulse width than that of the anodic phase. The wider pulse width is obtained by pulse trains.

Abstract: A cathodic protection system for use in an electrolyte includes a protected structure to be at least partially immersed in the electrolyte, at least one sacrificial anode to be at least partially immersed in the electrolyte and electrically connected to the protected structure, and a substantially impermeable barrier disposed between the at least one sacrificial anode and the electrolyte.

Abstract: A method for controlling microbial growth in potable water stored in a vessel having a metallic surface includes heating the metallic surface to a temperature between about 480° C. (900° F.) and about 870° C. (1600° F.), exposing the metallic surface to oxygen during heating to oxidize potential reduction sites on the metallic surface and charging potable water containing silver ions to the vessel. A vessel having a metallic surface is prepared for long-term storage of potable water containing silver ions by heating the metallic surface to a temperature between about 480° C. (900° F.) and about 870° C. (1600° F.) and exposing the metallic surface to oxygen during heating to oxidize electropositive metals on the metallic surface or by treating the metallic surface with an aqueous solution containing on oxidizing agent to oxidize potential reduction sites on the metallic surface.

Abstract: A method is disclosed for using an impressed current cathodic protection (ICCP) system that supplies an electrical current such that a metallic structure (10) has a negative voltage of between 0.5 and 1.5 Volt relative to earth to power one or more electrical appliances (5), the method comprising: —providing one or more electrical appliances (5) which each have a pair of electrical contacts (1,2); —connecting one electrical contact (1) of each electrical appliance to the structure; and —connecting the other electrical contact (2) of each electrical appliance to earth, thereby providing electrical power to each of the electrical appliances. It is preferred that the electrical appliances (5) are equipped with one or more DC-DC power converters (6) which are configured to enhance an electrical input voltage of between 0.5 and 1.5 Volt to an electrical output voltage of between 3 and 5 Volt.

Abstract: Techniques are generally described herein for protecting food or beverage containers (e.g., cans) using impressed current protection. In various embodiments, containers may be received into at least one conductive bed, each bed having a complementary anode. The containers may then be electrically coupled to a first terminal (e.g., negative) of a power supply, and the anode may be electrically coupled to a second terminal (e.g., positive) of the power supply. Resultantly, protective current may be provided to the containers by the anode.

Abstract: A process to reduce or prevent biofouling, by destroying or deactivating microbiological content of feedwater, or other liquid, prior to its entrance into membranes or process equipment, such as heat transfer equipment. The process comprises the use of electrical discharge and/or electric fields to destroy microbes that result in the biofouling of surfaces. By destroying the microbiological content of the water the microbiology no longer is able to create a restricting biofilm upon or within said process equipment.

Abstract: The present invention includes systems, methods and apparatus for continuously, independently and in some cases remotely monitoring the operation of a current interrupter used to test a cathodic protection system, or the cathodic protection system itself, for verification of proper operation. Embodiments of the invention include electronic devices that may be temporarily attached to a current interrupter that is being used to test a cathodic protection system, or directly to the cathodic protection system itself. Embodiments of the invention monitor the activity of an interrupter by sampling the output (voltage and time) to identify the cycle(s) of the interrupter. The invention provides truly independent verification since it does not need to know in advance the sequence or cycle times of the current interrupter being monitored. The information obtained by the invention is output so that it may be provided to a user, displayed, downloaded or stored for future reference.

Abstract: An apparatus, system, method and computer program product directed to controlling corrosion, particularly space weather induced corrosion, of a conductive structure in contact with a corrosive environment and coated with a semiconductive coating, where the corrosion is controlled by a controllable filter and a corresponding electronic control unit configured to process and adjust the controllable filter in response to at least one measured parameter associated with space weather effects on the conductive structure.

Abstract: A cathodic protection system wherein a metal structure is electrically connected to a sacrificial anode through a self encapsulating wire connector that can be assembled by unskilled persons and can be maintained in a protective condition around an electrical junction to enable the electrical junction to protected from an underground environment.

Abstract: The present invention generally relates to synergistic corrosion management systems designed to deliver two or more different types of corrosion inhibiting compounds (e.g., two or more different types of corrosion inhibiting compounds) to an enclosure, and to method for using same. More specifically, the present invention relates to synergistic corrosion management systems designed to eliminate, manage, control and/or mitigate corrosion in containers, enclosures, cisterns and/or storage tanks (e.g., above ground storage tanks). In one embodiment, the present invention utilizes a combination of at least one cathodic-based corrosion prevention or mitigation system, at least one soluble corrosion inhibitor, and at least one volatile or vapor phase corrosion inhibitor.

Abstract: The invention relates to a method that inhibits the formation of a deposition layer on metal surfaces in liquid submersion in a process susceptible to deposition, e.g. in an enrichment process. In the method, anodic current is supplied to the metal surface (11) to be protected against deposition via an external power source (100) and a cathode (12) immersed in the liquid, producing in the composition of the deposition adhering to the metal surface a change causing the adherence of the deposition to the surface (11) to be substantially weakened or the formation of deposition on a clean surface (11) to be substantially retarded.

Abstract: A sacrificial anode assembly for cathodically protecting and/or passivating a metal section, comprising: (a) a cell, which has an anode and a cathode arranged so as to not be in electronic contact with each other but so as to be in ionic contact with each other such that current can flow between the anode and the cathode; (b) a connector attached to the anode of the cell for electrically connecting the anode to the metal section to be cathodically protected; and (c) a sacrificial anode electrically connected in series with the cathode of the cell; wherein the cell is otherwise isolated from the environment such that current can only flow into and out of the cell via the sacrificial anode and the connector. The invention also provides a method of cathodically protecting metal in which such a sacrificial anode assembly is cathodically attached to the metal via the connector of the assembly, and a reinforced concrete structure wherein some or all of the reinforcement is cathodically protected by such a method.

Abstract: The present invention relates to a process for cathodic protection of electrode or electrode materials wherein negative bias is applied on the electrode. the negative bias is obtained by asymmetric current pulse. The asymmetric current pulse is obtained by performing negative phase with higher amplitude. The asymmetric current pulse is obtained by performing negative phase with wider pulse width than that of the anodic phase. The asymmetric current pulse is obtained by performing negative phase with higher amplitude and with wider pulse width than that of the anodic phase. The present invention further relates to a process for cathodic protection of electrode or electrode materials, wherein negative bias is applied on the electrode, wherein the negative bias is obtained by asymmetric current pulse, wherein the asymmetric current pulse is obtained by performing negative phase with wider pulse width than that of the anodic phase. The wider pulse width is obtained by pulse trains.

Abstract: A method for operating a system which inhibits the growth of marine organisms on a submerged surface causes a current to flow to one of two submerged surfaces over a time period that is selected as a function of the magnitude of the current and the area of the surface. In other words, the time period is determined as a function of the current density applied to the surface. In a particularly preferred embodiment the current density is maintained at approximately 35 milliamps per square foot and the time period is approximately four minutes. At the end of the time period, the current is reversed and a second submerged surface is polarized in a similar manner.

Abstract: This assembly provides a flexible method of attaching discrete sacrificial anodes to exposed steel in concrete construction to achieve an advantageous distribution of protection current. It comprises a base metal [1] that is less noble than steel, a conductor [6] connected to the base metal, a tying point [2] formed at least in part by the conductor, and a tie [4] that passes through the tying point [2] and around the steel [5]. The tie is used to physically tie the anode between steel bars prior to placing the concrete and in the process to electrically connect the anode to the steel. The tying point is open to facilitate adjusting the tie. The separation of the tie from an anode assembly with a tying point allows the tie to be selected during installation when the properties required by the application are known.

Abstract: The present invention relates to a process for cathodic protection of electrode or electrode materials wherein negative bias is applied on the electrode. the negative bias is obtained by asymmetric current pulse. The asymmetric current pulse is obtained by performing negative phase with higher amplitude. The asymmetric current pulse is obtained by performing negative phase with wider pulse width than that of the anodic phase. The asymmetric current pulse is obtained by performing negative phase with higher amplitude and with wider pulse width than that of the anodic phase. The present invention further relates to a process for cathodic protection of electrode or electrode materials, wherein negative bias is applied on the electrode, wherein the negative bias is obtained by asymmetric current pulse, wherein the asymmetric current pulse is obtained by performing negative phase with wider pulse width than that of the anodic phase. The wider pulse width is obtained by pulse trains.

Abstract: A novel cathodic protection system is provided that automatically controls and adjusts the voltage potential between an anode and a structure to protect the structure from corrosion. The cathodic protection system is self-powered, requiring no external power source or batteries. A cathodic protection circuit is configured to provide a cathodic protection current from the anode to the structure through an electrolyte. A power generation circuit is configured to generate power from a galvanic cell formed from the anode and an isolated electrode when cathodic protection is interrupted. A voltage potential control circuit is powered by the power generation circuit and is configured to (a) determine a structure-to-electrolyte reference voltage for the electrolyte and structure, and (b) adjust the cathodic protection current from the anode to the structure to maintain the reference voltage substantially the same as a set voltage.

Abstract: A method and apparatus for cleaning a wafer with a metal exposed through an insulator, through the use of a wet cleaning tank in concert with a feedback system on the potential difference between two leads of the wet cleaning tank. The cleaning tank has a bath in which the wafer and the two leads are immersed. The potential difference between the two leads is regulated when the feedback system detects a change in the potential across the two leads.

Abstract: A semi-permanent reference electrode for use in monitoring and measuring metals in field applications, such as cathodic protection. This electrode has an outer electrode body with a cap and porous plug. The outer electrode body is filled with a fill solution which is a saturated salt solution formed from a solid salt. The solid salt is hygroscopic with a low deliquescence point. An opening is provided in the cap to allow moisture into the outer electrode body to combine with the fill solution to maintain the saturated salt solution in the field. This saturated salt solution must maintain a constant pH for use in the semi-permanent reference electrode. A wire is used within the outer electrode body which connects to a voltmeter. This voltmeter measures the potential difference between the reference electrode and the field component of interest, which can include pipelines, storage tanks and bridges.

Abstract: In a method of reducing corrosion of a metal material, a substance such as semiconductor for generating an electric current by thermal excitation is coated or adhered on a metal material surface, to be exposed to a water having a high temperature of 150° C. or more, of a boiler and ducts or pipes, to which hot water heated by the boiler contacts, of a thermal electric power plant or a nuclear reactor structural material or ducts or pipes surrounding the reactor in a nuclear power plant.

Abstract: A pipe coupling for joining two electrolyte-conveying pipes of electrochemically dissimilar metals and inhibiting galvanic corrosion resulting from the dissimilarity. A tubular pipe coupling has a pair of axially spaced protection electrodes mounted to its interior wall in electrical contact with the electrolyte. A control electrode is also mounted to the interior wall of the tubular pipe coupling between one of the pipes and the pair of protection electrodes. A current sensing circuit is connected to sense the galvanic current through the control electrode. A controllably variable source of electrical current is connected to vary the current through the protection electrodes. A negative feedback control circuit receives the sensed current as a feedback signal and controls the variable source to increase the electrical current through the protection electrodes and the electrolyte so that the sensed current is reduced thereby reducing the galvanic current in the electrolyte between the pipes.

Abstract: A cathodic protection system is provided for cathodically protecting an metallic substrate against corrosion, where the system comprises a sacrificial anodic material containing, but not limited to, zinc, magnesium, aluminum or a mixture of these materials, with a ceramic magnet, coupled with a plug, embedded into the sacrificial anode in such a way as to take advantage of the magnetic flux for transfer of electrons from the sacrificial anode to the object being protected, the unit is affixed to the object being protected by use of an electrically-conductive adhesive. The electrical connection may be established via the combination of the ceramic magnet and the electrically-conductive adhesive. The magnet may be magnetized in the direction of its thickness.

Abstract: The present invention provides a curable cathodic corrosion protection powder coating, which comprises a thermosetting resin, a zinc borate compound, a curing agent in an amount effective to cure the coating. Further, the present invention also provides a method of cathode corrosion protection which includes the steps of subjecting the substrate to a mechanical treatment, applying to said treated steel surface, the cathodic protective coating, and polarizing the coated material as a cathode.

Abstract: A cathodic protection system for protecting an underwater structure includes a plurality of blocks which are capable of conforming to various structures. Each of the blocks include: a flexible wire rope, the rope constructed and arranged to pass through the center of each block in two directions, and embedded therein to fasten the blocks to each other by rows and columns; a sacrificial anode embedded in at least one of the blocks, and electrically attached inside the block to the flexible wire rope; and a connecting system electrically attached to the wire rope and to the underwater structure. Each block has a non-abrasive pad attached to it. The pad provides spacing between the block and the underwater structure. The system includes means for collecting performance data from the system. The sacrificial anode is made of a composition taken from the group comprising alloys of: zinc, aluminum, or magnesium.

Abstract: An apparatus, system, method and computer program product directed to controlling corrosion of a conductive structure in contact with a corrosive environment and electrically connected to one or more anodes, wherein the anodes are less noble than the conductive structure, where the corrosion is controlled by a controllable filter and a corresponding electronic control unit configured to process at least one stored or measured parameter, and wherein the apparatus, system and method serve to prolong the lifetime of the one or more anodes by reducing, minimizing or substantially eliminating their sacrificial character.

Abstract: A method for protecting metal-containing structures, in particular electrically conductive structures, deposited on a substrate, against corrosive attacks, in particular electrocorrosion attacks. The method applies at least temporarily to the structure a passivation electric voltage in the passivation range of the conductive material concerned.

Abstract: Cathodic protection of steel in a building or other concrete or similar structure is provided by locating an anode in a suitable location adjacent to the steel and providing an impressed current from a power supply to the anode. The anode is formed from a material which is more electro-negative than the steel so that in the event that the power supply falls below the galvanic potential therebetween, current flows under galvanic action to replace the impressed current. A diode in the circuit prevents flow of current across the power supply but allows the galvanic current when the power supply fails open circuit. An additional diode can be provided in the event the power supply fails closed circuit to prevent reverse current flow.