BACKGROUND OF INVENTION

The present application relates to a lightning detection and protection system.

One of the largest contributors of damage to electronic and electrical appliances is the natural occurrence of lightning. Lightning strikes cause damage for example by directly striking a building or striking electricity or telephone lines connected to the building, in both these cases, large surges of current are introduced into the electrical wiring of the building and any electrical appliances connected to the buildings electrical wiring are damaged or destroyed due to the lightning induced current surges.

The present invention seeks to address this.

SUMMARY OF INVENTION

According to one example embodiment, a lightning detection and protection system includes. a plug for plugging the system into a mains power supply outlet socket; at least one electrical socket for receiving a plug from an electrical appliance; a lightning detector to detect a lightning strike and to estimate the distance of the lightning strike from the detector; a communications module, responsive to the lightning detector, to communicate with a user that lightning has been detected; and a lightning protection module to disconnect the at least one electrical socket from the mains power electrical supply.

Typically, the lightning protection module disconnects the electrical socket from the electrical supply in response to the communications module receiving a message from the user to disconnect the electrical socket.

Generally, the lightning protection module disconnects the electrical socket from the electrical supply in response to the lightning detector detecting a lightning strike that is closer than a predetermined distance from the detector.

Preferably, the communications module communicates with the user by. (i) sending the user a message over a mobile communications network; (ii) sending a wireless or radio frequency message to a controller, which in turn relays the message to the user over a mobile communications network.

Typically, the message is an SMS or data message transmitted via a GPRS system.

Generally, the message includes a name of the lightning detection and protection system.

Preferably, the lightning detection and protection system further includes a plug detector to detect if a plug is inserted into or removed from the at least one electrical socket.

Typically, the communications module sends a message to a user to inform such user that a plug has been removed from the at least one electrical socket in response to the plug detector detecting this occurrence. Generally, the lightning detection and protection system further includes a memory having stored therein at least one cell phone number of a user.

Preferably, the lightning protection module includes one or more circuit breakers.

Typically, the lightning protection module includes relays or other isolation devices.

BRIEF DESCRIPTION OF THE DRAWING

A preferred embodiment of the invention will now be described in more detail, by way of example only, with reference to the accompanying drawing in which:

Figure 1 is a block diagram illustrating an example lightning detection and protection system.

DESCRIPTION OF EMBODIMENTS

Referring to the accompanying figure, a lightning detection and protection system is described.

The system is connectable to a mains power supply outlet which in the illustrated embodiment is a 220V AC input. The system typically includes a plug for plugging the system into a mains power supply outlet socket. Although the system has been illustrated as a 220V AC input system, it will be appreciated that the system could operate at any input voltage, including 110V AC input. The system also includes one or more electrical sockets into which electrical appliances can be plugged.

The input is connected to block A which is a lightning protection module (comprising circuits and components). The lightning protection module includes mains input protection unit, which is the first stage of the mains input circuit.

The lightning protection module may include gas discharge tube arrestors, metal oxide varistors, tranzorbs andVor energy dump resistors.

These devices collectively provide protection for a number of different potentially dangerous electrical events that can occur whilst the electrical appliances are connected to the mains powers via the outlet sockets. The tranzorbs provide fast protection for fast energy spikes up to certain voltage level.

The metal oxide varistors provide damping on energy spikes and surges for a higher level of voltage. The two device types are connected to energy dump low value resistors to absorb the energy under clamping conditions.

The gas discharge tube device is used to arrest very high energy events, typically lightning strike type events that carry very high energy pulses. Block 8 shows mains relay circuit breakers. In the illustrated embodiment, these include a single relay (double pole 16A 1107220V) that either connects the mains (live/neutral) to the socket outlet control relays or can be operated to go open circuit to isolate said circuit. It will be appreciated that although the system has been described using relay circuit breakers, it will be appreciated that other types of isolation devices may be used.

The relays/isolation devices are controlled by the micro controller device as will be discussed below. The coils are driven indirectry from the micro controller to activate the contacts. These two parts are electrically isolated from each other inside the relay housing

The primary function of the relays/isolation devices are to cut off the power supply to the socket outlets completely, should the need arise, in terms of lightning protection etc.

The prescribed maximum amperage allowance for extension boxes is 16 Amps <¾ 220V RMS. To this end. a current trip switch is used to sense the bulk amperage used for all the outlet sockets. If the current exceeds the maximum as stated, the current trip switch wilt cause the line voltage to be disconnected and stop the over current situation.

This situation can be reset via a user push button on the current trip switch. If after the reset has taken place and the over current situation is once again present the current trip switch will again be in effect, until such time as the over current situation is no longer present.

In essence, Block B is the master on/off contact control for the mains to be either connected or disconnected from the outlet sockets.

The circuit breakers illustrated form the heart of the lightning protection module to disconnect the outlet sockets from the inlet 220V AC line. Block C is a power source for the relay circuit breakers to provide DC voltage to these devices.

Block C also includes a circuit to detect the mains voltage level / existence thereof and suitable DC voltage output to power the battery re-charge circuit.

In addition to all these features, it also provides a means to detect mains flutter situations, where the mains voltage is rapidly cycled. This feature is called mains hysteresis. Essentially in this regard, the controller (Block D) looks to see if the mains voltage has gone to zero and will institute a time delay before attempting to re-connect the mains voltage after the mains voltage has been stable for a period of time This prevents connected electrical appliances from having rapid mains voltage fluctuations which can damage modern switch mode power supplies in said electrical appliances.

Considering the situation where the mains voltage itself goes to zero volts, there is still a DC voltage available to the micro controller circuit and relays/isolation devices, by means of a battery backup system. The controller can decide when to attempt a re-connect, taking into consideration the function of mains hysteresis as described above.

This Block C is protected by means of the function of Block A, which has been described above. In addition to the protection provided by Block A, this circuit has its own extra input protection as well (which is included in the lightning protection module).

Block D is a micro controller, which provides the intelligence, control and decision making. This is the central hub where all functions are realized and acted upon.

Block 0 consists of the micro controller itself and a real time clock. Communications to all of the other blocks such as the GSM unit, the lightning detection controller and the real lime clock are realized with this controller, using the UART and SPI peripheral controller interface ports.

AH the relays are also controlled via this controller from its input/output ports. All sensory inputs such as the plug insertion switch, the battery voltage level and the detection of mains voltage activity is monitored via the micro controller. The micro controller also has the task of analysing the data from the lightning detector and will make decisions based on what the analysis results are. This will be explained in more detail below. The firmware that is written to realize entirely the products functions and abilities, will reside on this micro controller. This firmware together with the micro controller provides all the necessary functions and decision making actions. Without this central controller, the system is not able to operate.

A user may set / modify various micro controller settings, including.

1. SOCKET AME: The identifier of the electrical appliance plug associated with an electrical socket of the system (optional). This identifier can be included in an SMS or other data message to the user (as will be described in more detail below) to assist the user to decide whether to disconnect the electrical socket from the mains power electrical supply.

2. ALERT RANGE. The range (i.e. kilometre range) within which lightning strikes are communicated to a user.

3. AUTO-DISCONNECT RANGE: The range (i.e. kilometre range) within which lightning strikes automatically cause the system automatically to disconnect the electrical socket from the mains power electrical supply (optional).

4. UNPLUGGING ALERT: Whether a SMS or data message alert is sent to a user in response to an electrical appliance plug being removed from an electrical socket of the system (optional). This could alert the user to potential theft of such electrical appliance.

5. SMS / DATA MESSAGE: Whether a SMS or data message alert is sent.

6. POWER DOWN ALERT: Whether a SMS or data message alert is sent to a user in response to the mains power supply going down.

7. ALARM: Whether to trigger an audible alarm on the system in addition to transmitting SMS or data message alerts. The micro-controller settings are altered either by SMS or by data messages (e.g. via an app communicating with the system via wifi).

The micro controller typically includes a memory for storing all of the information required by the system which will include the above-mentioned selected options as well as at least one cell phone number of a user with which the system will communicate and accept authorised instructions from as will be described below in more detail. it will be appreciated that in some embodiments the memory may be separate from but connected to the remainder of the components.

A communications module (comprising circuits and/or components) is comprised of Slock E (for example a Sim900 GSM Unit) together with the Sim Card socket illustrated.

The communications module enables the system to communicate with a user that lightning has been detected, as will be described in more detail below.

For the system to have wide area communications, namely the ability to send and receive SMS/data messages, this block is used to perform these tasks This block/unit has a uart interface to the micro controller, and a GSM band radio link to the outside world/cellular network.

Although the system has been described with the communications module communicating with users directly via SMS or data messages using the mobile communications network (including the GPRS system), it will be appreciated that the communications module may communicate with a user via a controller. For example, the communications module may communicate with a controller via wifi or RF signals, which controller in turn relays the message to the user via SMS or data messages using the mobile communications network (including the GPRS system). Because this Block £ is linked to the micro controller, it provides a means to interact with the system from a long distance away.

All the system information, alerts, commands are realized through using the well-known GSM cellular service (SMS/data) The system can send a SMS/data message to the user providing alerts and information and the user can send the system SMS messages to instruct the micro controller what to do via the GSM unit. It will be appreciated that other mobile communications protocols such as USSO may also be used to communicate with the user.

Essentially, this system is the go-between the user and the central controller of the electrical appliance, when at a distance from the extension box installation.

When a new SIM card is inserted into the system, this needs to acquire the numbers of users to whom alerts must be sent.

In order to do this, a user sends an SMS/data message from their mobile phone on which they wish to receive the alerts to the SIM in the system. Preferably, the SIM card is sealed in the system.

On receipt of the SMS/data message, the system:

1. Reads the SMS/data message.

2. Determines the cell phone number from which the SMS/data message was sent.

3. Registers this as an alert number (there are possibly more than one cell phone numbers for the alert).

4. Each cell phone number registered must be a separate SMS/data message.

Password functionality may be set up where the password would be setup as part of the hardware manufacture and then displayed on a sticker on the packaging. In this example the SMS/data message sent to the system must contain a valid password for the system to register the received SMS / data message for alerts.

There is also an LED bar graph to indicate to the user the level of RF signal received for the GSM unit. The system will also employ the use of an antenna that is compact and mounted inside of the extension box enclosure

An example of a communication message would be "We have detected lightning 5 kms from your appliance would you like to disconnect your appliance? Please reply Yes or No."

Thus it will be appreciated that the system must be able to receive communication back from the linked cell phone and interpret the message and react accordingly.

Messages will have to be fairly standard and the requirement communicated clearly in the outgoing message. The system must ignore caps lock i.e. Yes = yes - YES. Anything that is received and not recognized is interpreted as no response.

An SMS/data message can also be sent for a flat battery notification. Block F shows a battery backup for the digital parts of the circuit (micro controller / GSM / lightning detection) to remain operational when the mains is dis-connected. A single cell Lithium Ion re-chargeable battery pack was used in the prototype of the present invention. This will maintain the digital circuit at 3.3VDC irrespective of the mains being connected or not. Typical capacity of this battery pack will be in the order of 2200maH. The battery will sit in a user accessible cradle with spring retention mechanisms. The battery pack also allows the GSM unit to use high current usage peaks on transmit mode, as the GSM unit is connected directly to the 3.3VDC battery source The battery pack is kept charged via a suitable charge control circuit that is fed from the front end DC power supply. The charge rate to the batteries is kept at a low level to ensure long life of the batteries. The micro controller will also monitor the voltage level of the battery pack and go put the system into suspend mode if it detects that the battery pack voltage is too low to continue operations.

In the event of mains power outage and the DC to the battery charge circuit consequently being down for an extended period of time, the battery pack will rundown and the micro controller will attempt to alert the user that the system is about to shut down via an SMS or data message.

The act of having the mains voltage back on will allow the battery to start being re-charged through said charging circuit.

The micro controller is able to turn the other digital units in the circuit on and off through its own control method of supplying 3.3VDC to the respective units using well known high side mosfet electronic switches.

This method places the additional feature of peripheral digital units power supply under the control of the micro controller, which is vital for power saving and preventing over discharge of the battery pack. Over discharging of batteries in general is not recommended to the on-going batteries operational health

The user will also have a LED bar graph to visually indicate battery level at close visual range. Block G illustrates a lightning detector. A special RF analog/digital processing IC (integrated circuit) is used to delect lightning activity and estimating the distance of the lightning strike from the system. This unit uses a small very compact antenna in the form of an inductor to form a tuned circuit on the RF receiving end of the unit. The unit is of a receive only topology i.e. it only listens for certain band RF activity, no transmit function is possible, which is not needed. It is purely a listening device.

The system is connected to the micro controller on a S PI (Serial peripheral interface) bus This is a fast serial communications inter peripheral standard. The unit also has an output to create an immediate interrupt to the micro controller such that the micro controller does not need to constantly monitor the device for vital information. When the device causes the micro controller to access its information on the SPI bus, the unit passes all necessary information to the micro controller. From there the micro controller makes decisions based on the data the unit has sent to the micro controller.

The system is able to detect lightning activity due to the fact that lightning strikes cause a certain electromagnetic field to be generated and this is intercepted by the tuned RF front end of the system. The duration / field strength is analysed and if necessary passed onto the micro controller to make certain decisions. These decisions can be based on user preset settings to be informative and if necessary take full control if the user does not respond in time to certain strike distance limits.

This system is under full control of the micro controller, and as such can be turned on/off by the micro controller. The micro controller can also set various conditions in the system on how to respond to strike events. The unit is capable of detecting strike activity up to 30km away.

The extension block outlets are controlled on an intelligent basis via the micro controller. Each socket outlet has its own circuit breaker relay rated at 16amps 110 220 AC. These relays allow the micro controller to individually control the socket outlet is to be on or off. The relays are controlled via the micro controller using logic level to DC control methods i.e. supplying DC to the relay coils or not. If the DC is supplied to the relay coil, the Live (L) is switched through the relay contacts to the socket outlet connecting pin. If the DC is turned off the relay contacts go open thus turning off the socket outlet.

There is also a switch or opto coupled device situated on each socket earth pin to indicate if the user has inserted a plug or not into the extension box. These opto couplers essentially form a plug detector to detect if a plug is inserted into or removed from the electrical socket.

This is a totally electrical isolated sense method that does not require the monitoring of the 110/220VAC current used by the applied device. The extension box can be completely disconnected from the mains power supply and still detect insertion or extraction of the electrical appliance plug. This realizes a function of unauthorized plug insertion or extraction and can be used to alert the user of possible theft of connected electrical appliance to the extension box by way of an SMS/data message warning sent to the user via the communications module.

In addition to these features, each outlet also has a visual LEO/other indicator to show if the mains voltage is actually present at the outlet. The indicator is connected to the live (L) secondary side of the socket relay, so it actually only lights up when there is actual voltage present.

There is also a mains power input LED visual indicator to show the user at close range that the mains power is present and connected to the extension box. The main input relays secondary contact side is used for this purpose of connection to the LED indicator.

In a further example embodiment, the system includes functionality to allow the user to control appliances plugged into the system by switching on and off individual sockets of the system. As such, a remote user could, for example, switch on a lamp or radio that is connected to the system. The system may also be able to return a GPS location so that the location of the system can be determined on request. This will only be possible from the registered phone number. It will be appreciated that the present invention provides a lightning protection circuit which detects lightning, proactivety communicates with a user and disconnects electrical appliances from a mains power source without the user being present and thereby provides a very effective lightning protection system.