GB2582019A

GB2582019A - Method, system and device for detecting stray current corrosion conditions

Info

Publication number: GB2582019A
Application number: GB1903158.2A
Authority: GB
Inventors: Arthur Holloway John
Original assignee: Gillian Richards
Current assignee: Gillian Richards
Priority date: 2019-03-08
Filing date: 2019-03-08
Publication date: 2020-09-09
Anticipated expiration: 2039-03-08
Also published as: GB2582019B; GB201903158D0; WO2020183144A1

Abstract

A method, system and device for alerting a user to stray current in an aquatic environment 17 are disclosed. The system for alerting a user to stray current which may cause electrical corrosion to a vessel in a marine environment comprises: a dock having conductive moorings, a shore power system with at least one power connector for connecting a vessel to the power shore system. The system has at least one common grounding point; a monitoring and alert system 14 for monitoring a potential between the common 10 grounding point 18 and a body of water 17 in which the vessel is located. An alarm signal based on the monitored potential and once a predetermined threshold exceeded is generated. There may also be a remote status panel 26 which has visual indicators 32. The system may also have a wireless communication means 42 which is connected to a relay means 34. The relay means may disconnect the vessel from the shore power system. The 15 monitoring and alerting means 14 take voltage readings from additional sources 20 and 22.

Description

METHOD, SYSTEM AND DEVICE FOR DETECTING STRAY CURRENT CORROSION CONDITIONS The present invention generally relates to a method, a system and a device used for detecting and alerting a user to stray current which could cause corrosion, particularly to a marine vessel, through electrolytic corrosion in accordance with the galvanic series.

BACKGROUND TO THE INVENTION

Generally, corrosion is the process that refined metal undergoes to reach a more chemically-stable form. For example, refined iron undergoing an electrochemical reaction with oxygen to turn into iron oxide. In this reaction electrons of the refined iron are lost to the oxygen or other substances in the air. When the oxygen is reduced (gains the lost electrons) it forms the oxide with the metal. While this basic form of corrosion is damaging to a vessel, there have been many developments made to help slow or prevent it. However, there are other forms of corrosion which can damage vessels, for example galvanic corrosion which is particularly damaging Galvanic corrosion is an electrochemical reaction between two or more different metals or alloys which are in or connected by an electrolyte and share a common ground (electrically connected). The metals or alloys must be dissimilar with different electrode potentials. One metal or alloy has to be more chemically active than the other for a reaction to take place. The more chemically active metal or alloy is an anode and the less chemically active is the cathode. For example, an aluminum hull acting as the anode, a stainless steel component of a boat acting as the cathode and seawater acting as the electrolyte. Electrons flow from the anode to the cathode via the electrolyte. Metal atoms become ions because of the different number of electrons and break away into the electrolyte. The metal ions can bond with oxygen ions to form an oxide. The cathode cannot accumulate all the electrons from the anode and as such the electrons react with ions in the electrolyte causing a hydroxide ion. The hydroxide is alkaline which results in the electrolyte local to the cathode becoming alkaline. This type of corrosion can happen solely from the electric potential within metals. However, corrosion of this sort can be driven by an external potential. It can also be more damaging as the external potential can be much higher. This type of corrosion is known as stray current corrosion.

Stray current corrosion occurs when there is an electrical current flowing through the metals immersed in the electrolyte which is grounded. Current can flow through the metal into the electrolyte and towards ground. In a similar fashion the anode which is less chemically active releases electrons and ions during corrosion. The external electrical power is a system essentially separate from the potential of the metal themselves, for example a boat may be docked at a pontoon and connected to the shore power system, or it may be the vessel's battery. If a ground fault should occur, current would flow into the boats metal components and out through the electrolyte towards a ground, this would result in the anode corroding.

Unfortunately, stray current corrosion can not only affect the vessel leaking current but also those which share a spaceS For example, a vessel not leaking current may be located near or between a vessel leaking current and an electrical ground. Instead of the current flowing directly to ground it would take the path of lower resistance, i.e. through the vessel not leaking current. The stray current could enter the vessel not leaking current through a conductive means, for example a hull fitting, and enter into the bonding system (shared ground) then leave through another conductive means in contact with the water.

The vessels do not necessarily have to be in close proximity but could share a common ground, such as the ground wire of the AC shore power system which could result in significant DC voltage levels on the common ground wire as a result of a DC leakage fault on another vessel. In one scenario, a major fault occurs on board a boat resulting in voltage levels of 12 volts DC or more on the shore ground wire. The shore ground wire is common to every other vessel that may be docked on the pontoon. This can result in substantial levels of damaging DC current flowing through any boat on that pontoon, and rapidly destroying the underwater metals of those boats. Stray current corrosion can typically cause serious damage within 1 to 4 weeks. There is no indication either on the boat with the fault or any other boat undergoing corrosion through electrical means. This can be an issue as the owner may leave the vessel docked in the marina for extended periods and the marina staff are unlikely to see corrosion occurring under the water line. Unfortunately, because this type of corrosion is not easily detected and can happen despite the best efforts of vessel owners it can be difficult to find who is at fault, if anyone It is DC current which is the main cause of this corrosion, and this DC component can exist on the common ground wire of an AC power source.

Commonly, a vessel connects to the shore power system. The shore power system can provide power to a number of vessels. When these vessels are connected they share a common ground which can be in the form of the shore ground wire. Ideally, this ground wire should be at zero volts when measured against the electrolyte potential, but due to factors such as the length of pontoon cable runs, water resistance, and some superimposed voltage, the common ground wire is normally around 0.1 to 0.3 volts above zero.

To help limit or prevent the above types of corrosion, it is common to use sacrificial anodes. These sacrificial anodes are placed below the water line to protect the more expensive underwater components and metals, such as the bronze propeller, stainless steel shafts, and aluminium outdrives. These sacrificial anodes are usually a metal which is more reactive, such as zinc. These sacrificial anodes should be regularly inspected and periodically changed as they naturally erode providing protection to the more noble boat metals. Furthermore, any increase in the level of current flowing through the sea water leads to the sacrificial anodes depleting at a quicker rate.

Another form of protection is known as a Galvanic Isolator. This isolator is fitted in series with a shore power ground wire and will give protection up to a potential difference of 1.4 volts, or in some cases 2.8 volts However, at higher voltages a galvanic isolator offers no protection.

A further form of protection is the use of isolation transformers which breaks the electrical continuity between the shore power and the vessel, especially the ground wire These transformers typically work by connecting all metal parts to the neutral output on the secondary side of the transformer (the side connected to the vessel). These transformers are expensive compared to galvanic isolators. They can be relatively large and heavy compared to other means, and are generally only fitted to larger vessels.

It is an object of the present invention to reduce or substantially obviate the aforementioned problems.

STATEMENT OF INVENTION

According to a first aspect of the present invention, there is provided a method I 0 of alerting an individual to stray current in a marine environment which may cause electrical corrosion to a boat, vessel or marine structure, the method comprising the steps of monitoring, by a monitoring device, a DC potential between a ground of a power system connected to the boat, vessel or marine structure and a body of water where the boat, vessel or marine structure is located; wherein the monitoring device comprises a reference probe for deployment in the body of water and a first voltage sensor for determining the DC voltage on the ground of the power system; and generating an alert signal if the monitored potential of the ground in relation to the reference probe meets or increases above or exceeds a predetermined threshold.

Using the disclosed methods, it is possible to detect the conditions which produce electrical corrosion while alerting the owner of the vessel or marina staff to the conditions which may cause corrosion. This means action can be taken at the earliest opportunity to stop the cause of corrosion. Furthermore, it ensures that it is possible to protect from voltage levels higher than those of a galvanic isolator solution.

Additionally, the method can assist in detecting and catching the cause of corrosion across a number of vessels in a body of water.

Furthermore, the device is a passive monitoring device. There is no need to impose or impress a current onto the reference probe or anode.

The method may monitor the potential between a ground wire of a shore power system connected to a boat. The first voltage sensor may determine the DC voltage on the ground wire of the shore power system.

The method may further comprise monitoring a second potential between a bonding system of the boat (common ground within the vessel), vessel, or marine structure and the body of water. The monitoring device may comprise a second voltage sensor for determining the voltage on the bonding system of the boat, vessel or marine structure.

By monitoring a second potential at a second location it is possible to monitor for any current leakage through the bonding system of the boat, vessel or marine structure I 0 The method may further comprise monitoring a third potential between a radio ground plate located on the vessel and the body of water. The monitoring device may comprise a third voltage sensor for determining the voltage on the radio ground plate.

By monitoring a third potential at a third location it ensures that many of the common locations for current leakage to occur are monitored.

The method may further comprise transmitting the alert signal to a status panel The status panel may generate a visual and/or audible alarm based on the alert signal.

By using visual and audible alarms on a status panel it makes it simpler to tell the condition of the monitoring system. It also allows for remote locations or personnel to be provided with information about the status of the monitoring system.

The status panel may be located remote to a boat such as on a pontoon, dock, mooring or other structure within the marine environment. The status panel may be located on a vessel Haying these locations allows for the status to be more easily noticed, particularly as it is in a location regularly visited by owners or marina staff.

The status panel may include input means to control the function of the panel and/or monitoring unit. The input means may be tactile input means, such as push buttons and/or switches. There may be at least one switch or push button which can perform at least one of the functions of testing, silencing and resetting.

The button may have a combination of actuations to achieve a function.

Alternatively, there may be a plurality of switches and/or push buttons each performing a separate function.

The input means allows for the status panel to control the monitoring means from a location remote to the monitoring and alerting unit. For example, it allows for the monitoring unit or device to be reset so that an alarm signal is not generated.

Resetting may be done automatically. For example, the alert signal and/or alarm can be stopped if the monitored potential drops below the predetermined threshold. This ensures that should the conditions for corrosion disappear then the alerts and alarms may stop after a predetermined time The predetermined thresholds may be determined based on the various potentials which are known to cause electrical corrosion.

The predetermined thresholds may be set according to potentials which are associated with a specific metal or alloy component(s), such as those of a vessel with the device. This could be pre-set or achieved in the field by a selection device such as a dial, a knob or a potentiometer within the monitoring unit, system or device.

The monitoring system may transmit the alert signal to a wireless communication means. The wireless communication means may generate and send an alert message or signal to at least one mobile device or smart device By using a wireless communication means it is possible to transmit alerts to remote devices, such as mobile devices. It also allows for communication with a smart device. This ensures that even in the event of the marina or dock being left unattended, or the owner leaving the vessel docked, an alert won't be missed.

The wireless communication means may include a GSM communicator. The wireless communication means may include a GSM module and GSM antenna. The message may be transmitted to an owner or marina staff through a cellular network, internet or local computer network.

A GSM system allows for the communication to be transmitted over cellular networks. This increases the likelihood of the communication reaching its intended recipient. It also means that there is no sole reliance on other means of wireless communications.

The method may include the step of triggering a relay to disconnect the vessel from the shore power system based on the alert signal. Alternatively, the GSM communicator/module may receive instructions from the mobile device or smart device. These instructions can be used to control the monitoring device or relay.

By having a two-way communication means it is possible to take action while being in a location remote to the vessel According to a second aspect of the present invention there is provided a system for alerting a user to stray current which may cause electrical corrosion to a vessel in a marine environment, the system comprising a pontoon, a shore power system with at least one power connector for connecting a vessel to the power shore system, and at least one common ground; a monitoring and alert system for monitoring a potential between the common ground and a body of water in which the vessel is located, and generating an alarm signal based on the monitored potential of the ground in relation to the reference anode and a predetermined threshold.

The disclosed system has all the advantages associated with the disclosed method and device.

The system may be considered as a ground wire voltage monitor for a marina, a pontoon within a marina or other marine platform or structure. I 0

The system may be considered a Marina pontoon ground wire voltage monitor, with the option of an alarm system and/or wireless alert.

The monitoring system may also monitor the potential between a bonding system of the vessel and the body of water. The bonding system of the boat may be the common ground shared between the components of the vessel.

The monitoring system may also monitor the potential between a radio ground plate and the body of water in which the vessel is located. I 0

The system may further comprise a status panel connected to the alarm system, wherein the status panel generates an audio and/or visual alarm when an alarm signal is received.

1S The system may further comprise a wireless communication means, wherein the wireless communication means generates and sends an alert message to a mobile device or smart device when an alarm signal is received The system may further comprise a power shut-off relay, wherein the power shut-off relay is adapted to stop or prevent power from the shore power system being supplied to or connected to the vessel. The power shut-off relay may be triggered by the monitoring and alert system or the wireless communication means. An important feature of the shut-off relay is that it can also disconnect the ground wire.

According to a third aspect of the present invention there is provided a monitoring device for detecting stray current in a marine environment, the device comprising a reference anode for placement into a body of water within a marine environment; a first voltage sensor for determining the voltage on a common ground; a monitoring and alarming means configured to determine a first potential between the reference anode and the first voltage sensor and generate an alarm or alert signal based on the determined potential of the ground in relation to the reference probe meeting or increasing above or exceeding a predetermined threshold.

The disclosed device has all the advantages associated with the disclosed method and system.

The device may be considered as a ground wire voltage monitor. The device may further include an auxiliary relay output. The device may be connected to a remote alarm panel.

The common ground may be a ground wire of a shore power system connected to a vessel located within the body of water. I 0

The common ground may be the earth bonding system of the vessel. The monitoring and alarming means may have a second voltage sensor for determining the voltage on the earth bonding system of the vessel. The monitoring and alarming means may also determine a second potential based on the difference between the reference 1S anode and the second voltage sensor.

The common ground may be a radio ground plate. The monitoring and alarming means may comprise a third voltage sensor for determining the voltage on a radio ground plate. The monitoring and alarming means may also determine a third potential based on the difference between the reference anode and the third voltage sensor.

The device may comprise a connection means adapted to transmit the alarm signal to a status panel for creating an audio and/or visual alarm.

The alarm signal may be transmitted to a wireless communication means for transmitting an alert message or signal to at one least mobile device or smart device.

The wireless communication means may include a GSIVI communicator and a GSM antenna. 3 0

The device may further comprise a housing for enclosing at least some of the components The device may comprise a relay for disconnecting a supply of electricity from the shore power system to the vessel.

The device may comprise a relay output for triggering a relay to prevent or stop power from the shore power system being connected to or supplied to the vessel.

In another aspect of the present invention, there is provided a method of alerting a user to stray current in a marine environment which may cause electrical corrosion to a vessel, the method comprising the steps of monitoring, by a monitoring device, a potential between a ground common to electrically conductive components and a body of water where the vessel is located, wherein the monitoring device comprises a reference probe for deployment in the body of water and a first voltage sensor for determining the voltage on the common ground; and generating an alert signal if the monitored potential increases above, meets or exceeds a predetermined threshold.

The visual alarm representing that the monitored potential has been met, increased above, or exceeded the predetermined threshold may be a LED. The LED may be red in colour or it may be another colour. The LED may flash or produce a solid colour to indicate that the monitored potential has met, increased above or exceeded the predetermined threshold.

In any of the aspects of the invention there may be a plurality of additional alert or alarm signals generated based on the monitored potentials of the grounds in relation to the reference probe which represents the severity of the possible conditions related to stray current.

A first additional alert or alarm signal may be generated based on the monitored potentials of the grounds in relation to the reference probe approaching but not exceeding or increasing above the predetermined threshold.

A first additional alert or alarm signal may be generated based on if the monitored potential has not yet exceeded the predetermined threshold but is within a predetermined range or a predetermined percentage of the predetermined threshold. For example, the first additional alarm signal could be generated if the monitored potential is within 5% of the predetermined threshold. The predetermined percentage could be any percentage, for example, it could be between 20%, 10%, or 5% or any suitable percentage A second additional alert or alarm signal may be generated based on the monitored potentials of the grounds in relation to the reference probe meeting, increasing above or exceeding a second predetermined threshold. The second predetermined threshold is higher than the first threshold value.

The second threshold value may be determined based on a percentage increase on the first threshold value. For example, 10%, 15%, 20% or any suitable percentage The additional alert or alarm signals may be used to initiate an additional audio alarm and/or visual alarm. Alternatively or in combination, the additional alert or alarm signals may be used to generate and send a message, signal, or data to a mobile device or smart device This additional audio and/or visual alarm may indicate that the monitored potential is approaching the predetermined threshold or vastly exceeds/increases above the predetermined threshold The first additional alert or alarm signal may be used to activate a first additional audio and/or visual alarm.

The first additional visual alarm may be an amber LED.

The first additional audio alarm may be less severe. For example, the first audio alarm may have a lower sound intensity than the audio alarm triggered by the monitored potential meeting or increasing above or exceeding the predetermined threshold.

The second additional alarm or alarm signal may be used to initiate a second additional audio and/or visual alarm.

The second additional visual alarm may be an additional LED which is brighter or flashes quicker than other visual alarms.

The second additional audio alarm may be more severe. For example, the first audio alarm may have a higher sound intensity than the audio alarm triggered by the monitored potential meeting or increasing above or exceeding the predetermined threshold The ground common to electrically conductive components may be either a common ground associated with a shore power system, a ground common to the components within a vessel or a radio ground plate. The common ground associated with a shore power system, may be a common ground wire or the grounding point for the shore power system The reference anode may be constructed from zinc. It may also be a zinc alloy or constructed from any suitable material.

In another aspect of the present invention, there is provided a method of monitoring for stray current in a marine environment which may cause electrical corrosion to a metal or alloy, the method comprising the steps of monitoring, by a monitoring device, a potential between an electrical ground electrically connected to the metal or alloy and an electrolyte in contact with the metal or alloy; wherein the monitoring device comprises an electrolyte reference probe and a first voltage sensor for determining the voltage on the electrical ground; and generating an alert signal if the monitored potential of the ground in relation to the reference probe increases above a predetermined threshold.

Any of the aspects of the invention may include a galvanic isolator. Alternatively, the unit, system or device may be retrofitted to already existing corrosion protection systems or devices using a galvanic isolator.

Any of the aspects disclosed may monitor the potential between the galvanic isolator and the reference probe. The alert or alarm signal may be based on the monitored potential of the galvanic isolator in relation to the reference probe meeting, increasing above or exceeding a predetermined threshold.

The monitoring unit, monitoring device, or the monitoring system may function as a hi-stable switch. The bi-stable switch may have a first mode of operation and a second mode of operation The first mode of operation may be a monitoring mode. In this mode the bi-stable switch performs the function of monitoring the various common grounds (e.g. shore ground wire, common ground on vessel, and/or radio ground plate) and/or the galvanic isolator.

The second mode of operation may be an alarm mode. In this mode the bi-stable switch performs the function of generating an alert or alarm signal which is used to perform the alert or alarming functions. These may include an audio alarm, a visual alarm, a digital message such as text, and/or triggering the relay.

The bi-stable switch may have at least one opto-coupled input, but may have a plurality of opto-coupled inputs.

According to another aspect of the present invention there is provided a vessel comprising a monitoring device for detecting stray current in a marine environment and alerting a user, the device comprising a reference anode for placement into a body of water within the marine environment; a first voltage sensor for determining the voltage on a common ground; a monitoring and alarming or alerting means to determine a first potential between the reference anode and the first voltage sensor and generate an alarm or alert signal based on the determined potential of the ground in relation to the reference probe meeting or exceeding a predetermined threshold.

According to another aspect of the present invention there is provided a vessel which may have a combination or all the features of any other aspect of the invention.

According to another aspect of the present invention there is provided a pontoon comprising a monitoring device for detecting stray current in a marine environment and alerting a user, the device comprising a reference anode for placement into a body of water within the marine environment; a first voltage sensor for determining the voltage on a common ground; a monitoring and alarming or alerting means to determine a first potential between the reference anode and the first voltage sensor and generate an alarm or alert signal based on the determined potential of the ground in relation to the reference probe meeting or exceeding a predetermined threshold.

According to another aspect of the present invention there is provided a pontoon which may have a combination or all the features of any other aspect of the invention.

The features in any of the aspects of the invention may be combined with or replace features of other aspects of the invention.

The reference anode or probe (in any aspect of the invention) may have any one or more of the following features. The reference anode or probe may be attached to, attachable to, or part of a vessel hull, or another part of a marine vessel. Preferably, the part is normally disposed below the waterline when stationary in a body of water. The reference anode or probe may be connected to or connectable to a fixed location. That is, a location which is or not on a moving part, or, put another way, a location which is substantially immobile or static.

The reference anode or probe may include zinc or any other suitable metallic 20 material.

The reference anode or probe may be a sacrificial anode of a vessel.

A reference anode or probe may be provided in a marina or other body of water.

A plurality of references anodes or probes may be provided in a marina or other body of water. For example, a float or buoy (or series or floats or buoys) with a reference anode or probe may be provided. The reference anode(s) or probe(s) may be attached to at least one fixed or substantially immobile structure located within the body of water. This may be suitable for larger marinas or bodies of water. A remote connection to the anode(s) or probe(s) may be provided. This means that a reference anode of probe (or set of anodes / probes) can be used as a common anode / probe by multiple vessels or monitoring devices.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, and to show more clearly how it may be carried into effect, reference will now be made by way of example only to the accompanying drawings, in which: Figure 1 shows a schematic of a monitoring device according to a first embodiment of the present invention; Figure 2 shows a schematic of a monitoring device according to a second embodiment of the present invention; 1S Figure 3 shows a schematic of a monitoring device according to a third embodiment of the present invention; and Figure 4 shows a schematic of a remote status panel used in some embodiments of the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

Figure 1 shows a monitoring device 10 for detecting stray current in a marine environment according to a first embodiment of the present invention. The monitoring device 10 has a housing 12 enclosing a monitoring and alarm unit 14. The unit 14 has a PCB with electrical components and conductive traces. The monitoring device 10 is located on a vessel (not shown). The housing comprises a number of inputs or ports for receiving conductive cables. The monitoring unit 14 is connected to a reference anode 16 by means of an input. The reference anode 16 is located in a body of water 17 and may be made from zinc or any other suitable metallic material. The monitoring unit 14 includes a first isolated input means 18, a second isolated input means 20 and a third isolated input means 22.

In the current embodiment, the monitoring and alarm unit 14 has a power input 24 which is connected to a vessel's power supply through a fused connection. The monitoring and alarm unit 14 requires an input of 10 to 30 volts DC In other embodiments, the monitoring and alarm unit 14 is connected by the power input 24 to the shore power supply via a 220volt AC/DC adaptor, through a fused connection or may be connected to another power source such as a battery.

In the current embodiment, each isolated input means is connected directly to the ground point to be monitored for measuring voltage on the shore power ground wire (not shown) the vessel grounding system (not shown) and a radio ground plate (not shown) However, in other embodiments only the first isolated input means 18 receives readings directly from the shore power ground wire. The monitoring and alarm unit 14 monitors the potential between the reference anode 16 and each of the isolated inputs 18, 20, 22. If the potential is above, meets or exceeds a predetermined threshold the monitoring unit generates an alert signal.

In some embodiments the PCB in the monitoring and alarm unit 14 may include or act like a bi-stable switch. The bi-stable switch has a first mode of operation and a second mode of operation. In the first mode of operation the PCB monitors the voltage detected on each of the three opto-coupled inputs 18, 20, 22 using the reference anode 16. If the potential on any of the three opto-coupled inputs 18, 20, 22 meets or exceeds a pre-set value then the PCB is switched to the second mode of operation. The second mode of operation is an alarm mode in which the PCB generates and sends an alarm or alert signal.

The alarm or alert signal that is generated is sent to a remote status panel 26. The remote status panel is connected to monitoring device 10 through a conductive cable 28 interfacing with an input in the monitoring device 10. The conductive cable 28 is a twisted pair cable, such as a cat5 cable. The remote status panel may have three tactile input means 30 for controlling operation and include three visual indicators 32 for indicating information. In the current embodiment, the remote status panel 26 is located on a vessel in a suitable position. In other embodiments, the remote status panel may be located on a pontoon within a dock The monitoring unit 14 is connected to a relay 34. The relay can control the vessels connection to the shore power system. In response to the potential rising above the threshold, the monitoring unit may control the boat's connection to the shore power system through means of the connected relay 34.

The monitoring device 10 may be retrofitted to an existing vessel alarm system, such as Yacht Sentinel Y S5 or YS6 models. Other embodiments may also be retrofitted to existing alarm systems.

Figure 2 shows a second embodiment of the monitoring device according to the present invention. The monitoring device 40 works in a similar fashion to the first embodiment 10 and has all the same features. However, the monitoring device 40 includes a wireless communication means for transmitting a message, data or signal to a user device. In the current embodiment, the wireless communication means is a GSM communication system. The GSM communication system comprises a GSM communicator 42 and a GSM antenna 44. The GSM communicator 42 can be in communication with a cellular network through the GSM antenna 44. In response to the alert signal from the monitoring and alert unit 14, the GSM communicator 42 transmits through the antenna 44 an alert message to the cellular network for communication with at least one mobile device or smart device. The mobile device or smart device can communicate instructions to the monitoring device 40 through the GSM communicator. In the current embodiment, the relay is connected to the GSM communicator 42. The instructions the GSM communicator 42 receives can be used to control the relay 34 to disconnect the vessel from the shore power system. The alert message may be communicated to appropriate targets, which could include the vessel owner or marina staff The monitoring device 40 may store the relevant addresses such as IP or MAC addresses or phone numbers for the mobile or smart devices.

Figure 3 shows a third embodiment of the monitoring device according to the present invention. The monitoring device 50 works in a similar fashion to the first and second embodiments. In the current embodiment, the monitoring device 50 is not connected to the relay or the remote status panel. Furthermore, the monitoring and alert unit 14 only receives a signal through the first isolated input 18. The first isolated input 18 is connected to a voltage probe or sensor and is used to measure the shore power system ground or common ground between all vessel located at the same pontoon The device of this embodiment may still include input means for later connection to voltage sensors located at other grounds The first, second and third embodiments of the monitoring device 10, 40, 50 can be used either on a vessel or within a marina in which a vessel is located.

Figure 4 shows an embodiment of the remote status panel 60 which can be used in other embodiments or aspects of the present invention. The remote status panel 60 comprises a housing, frame or facia 62 which at least partially encloses the electronics and the cabling used in the remote status panel 60. The remote panel 60 may receive an alert signal from a monitoring device through a communication cable 62. The panel 60 has three visual indicators in the form of a first LED 66 to indicate power, a second LED 68 to indicate the device is in monitoring mode or to indicate a monitoring status, and a third LED 70 which indicates that the monitoring device has sent an alert signal or is in alarm mode. The third LED 70 may be a different colour and/or flash to indicate an alert. The remote status panel 50 includes an audible alarm 72 which may be remotely connected to the remote status panel or built into the remote status panel. The audible alarm 72 generates a sound which alerts individuals in close proximity that there has been an alert signal generated by a monitoring device. The LEDs may produce a solid colour or may flash, for example, in a pattern to indicate an alarm or monitor status.

In the current embodiment, the Remote status panel includes three tactile input means, such as push buttons. However, in other embodiments they may be other types of input means. The first push button 74 is a momentary push button which is used to test the function of the visual indicators and audible alarms. The second push button 76 is a momentary push button which will silence the audible alarm for a predetermined time period. The second push button 76 will not prevent the third visual indicator 70 from indicating an alert. If there is still an alert signal after the predetermined time period, the audible alarm will sound again. The third push button 78 is a reset button which resets the monitoring and alarm unit within the monitoring device, the audible alarm, and the visual indicators. The remote status panel 60 may send a reset signal to the monitoring and alarm unit through the cable 64 as a result of pressing the third button 78.

In another aspect of the present invention, there is provided a method of alerting a user to a stray current in a marine environment. In this embodiment a monitoring device is attached to a ground point and a reference anode. The potential ground point includes such things as a common ground wire connected to a shore power system, a common ground for components within a vessel, or a radio ground plate. The monitoring unit determines a potential between the ground point and the reference anode. If the potential is above a threshold than the monitoring unit generates an alert signal. The alert signal can then be used to generate an audio and/or visual alarm at a remote status display located on a vessel or on a dock. Alternatively or in combination, the alert signal is used to generate an alert message which is transmitted wirelessly to a mobile device or smart device. The monitoring device can monitor multiple potentials between the reference anode and multiple ground points. If any of the potentials increase above the predetermined threshold an alert signal is generated. The current aspect can be used with another aspect of the present invention. For example, the method may use the monitoring devices discussed in reference to figures 1 to 3. It may also use the remote status panel discussed in relation to figure 4.

In another aspect of the present invention there is a system for alerting a user to stray current. The system includes a dock constructed from conductive material. The dock also has at least one power connector used to connect a vessel to a power shore system. The power connector shares a common ground with all other power connectors.

The system also includes a monitoring and alarming system, this can be the same as those discussed in other embodiments. The monitoring and alarming system works in the same manner as discussed in other embodiments of the present invention.

The embodiments described above are provided by way of example only, and various changes and modifications will be apparent to persons skilled in the art without departing from the scope of the present invention as defined by the appended claims

Claims

CLAIMSI. A method of alerting a user to stray current in a marine environment which may cause electrical corrosion to a vessel, comprising the steps of: monitoring, by a monitoring device, a potential between a ground wire of a shore power system connected to the vessel and a body of water where the vessel is located; wherein the monitoring device comprises a reference probe for deployment in the body of water and a first voltage sensor for determining the I 0 voltage on the ground wire; generating an alert signal if the monitored potential on the ground wire in relation to the reference anode increases above a predetermined threshold. 2. 3. 4.
A method as claimed in claim 1, further comprising monitoring, by the monitoring device, a second potential between a ground bonding system of the vessel and the body of water; and generating the alert signal if the second potential increases above a predetermined threshold, wherein the monitoring device comprises a second voltage sensor for determining the voltage on the ground bonding system of the vessel.
A method as claimed in any of the preceding claims, further comprising monitoring, by the monitoring device, a third potential between a radio ground plate located on the vessel and the body of water in which the vessel is located, and generating the alert signal if the third potential increase above a predetermined threshold; wherein the monitoring device comprises a third voltage sensor for determining the voltage on the radio ground plate.
A method as claimed in any of the preceding claims, in which the alert signal is transmitted to a status panel which generates a visual and/or audible alarm.
A method as claimed in claim 4, in which the status panel is located either on a pontoon within the marine environment or on the vessel.
6. A method as claimed in either claim 4 or 5, in which the status panel includes one or more switches and/or push buttons which allow for the alarm to be at least one of tested, silenced or reset
7 A method as claimed in any of the preceding claims, in which the alert signal is transmitted to a wireless communication means for sending an alert message or signal to at least one mobile device or smart device.
8. A method as claimed in any of the preceding claims, in which the alert signal is used to trigger a relay to disconnect the vessel from the shore power system.
9. A system for alerting a user to stray current which may cause electrical corrosion to a vessel in a body of water in a marine environment, the system comprising: a pontoon, a shore power system with at least one power connector for connecting a vessel to the power shore system, and at least one grounding point; and a monitoring and alert system configured to monitor a potential of the grounding point, and configured to generate an alarm signal based on the monitored potential on the grounding point in relation to a reference anode and a predetermined threshold.
10. A system as claimed in claim 9, in which the monitoring system also monitors the potential between a ground bonding system of the vessel and the body of water.
11 A system as claimed in claims 9 or 10, in which the monitoring system also monitors the potential between a radio ground plate and the body of water.
12. A system as claimed in any of claims 9 to 11, in which the system further comprising a status panel connected to the alarm system, wherein the status panel generates an audio and/or visual alarm when an alarm signal is received.
13. A system as claimed in any of claims 9 to 12, further comprising a wireless communication means, wherein the wireless communication means generates and sends an alert message to a mobile device when an alarm signal is received
14 A system as claimed in any of claims 9 to 13, further comprising a power shut-off relay, wherein the power shut-off relay stops or prevents power from the shore power system being supplied or connected to the vessel as a result of the alert signal.
15 A monitoring device for detecting stray current in a marine environment comprising: a reference anode for placement into a body of water within a marine environment, a first voltage sensor for determining the voltage on a ground wire of a shore power system connected to a vessel located within the body of water; and a monitoring and alarming means to determine a first potential between the reference anode and the first voltage sensor, and generate an alarm signal based on the determined potential on the ground wire in relation to the reference anode being at or above a predetermined threshold.
16. A device as claimed in claim 15, in which the device comprises a second voltage sensor for determining the voltage on a ground bonding system of the vessel, and the monitoring and alarming means also determines a second potential based on the difference between the reference anode and the second voltage sensor, and generates the alarm signal to be based on at least one of the first or second determined potentials on the ground in relation to the reference anode being at or above a predetermined threshold
17. A device as claimed in claim 16, in which the device comprises a third voltage sensor for determining the voltage on a radio ground plate, and the monitoring and alarming means also determines a third potential based on the difference between the reference anode and the third voltage sensor, and generates the alarm signal to be based on one or more of the first, second or third determined potentials on the ground in relation to the reference anode being at or above a predetermined threshold.
18. A device as claimed in any of claims 15 to 17, comprising a connection means adapted to transmit the alarm signal to a status panel for creating an audio and/or visual alarm.
19 A device as claimed in any of claims 15 to 18, in which the alarm signal is transmitted to a wireless communication means for transmitting an alert message or signal to at least one mobile device or smart device.
20. A device as claimed in claim 19, in which the wireless communication means includes a GSM communicator and a GSM antenna.
21 A device as claimed in any of claims 15 to 20, in which the device comprises a relay output for triggering a relay to stop or prevent power from the shore power system being supplied or connected to the vessel.
22. A method of alerting an individual to stray current in a marine environment which may cause electrical corrosion to a metal or alloy, the method comprising the steps of monitoring, by a monitoring device, a potential between an electrical ground electrically connected to the metal or alloy and an electrolyte in contact with the metal or alloy; wherein the monitoring device comprises an electrolyte reference probe and a first voltage sensor for determining the voltage on the electrical ground; and generating an alert signal if the monitored potential of the ground in relation to the reference probe increases above a predetermined threshold.
23. A vessel comprising a monitoring device for detecting stray current in a marine environment and alerting a user, the device comprising: a reference anode for placement into a body of water within the marine environment; a first voltage sensor for determining the voltage on a common ground, and a monitoring and alarming or alerting means to determine a first potential between the reference anode and the first voltage sensor and generate an alarm or alert signal based on the determined potential of the ground in relation to the reference probe meeting or exceeding a predetermined threshold.
24. A pontoon comprising a monitoring device for detecting stray current in a marine environment and alerting a user, the device comprising: a reference anode for placement into a body of water within the marine environment; a first voltage sensor for determining the voltage on a common ground; and a monitoring and alarming or alerting means to determine a first potential between the reference anode and the first voltage sensor and generate an alarm or alert signal based on the determined potential of the ground in relation to the reference probe meeting or exceeding a predetermined threshold