GB2557600A

GB2557600A - Device for monitoring an electrical apparatus

Info

Publication number: GB2557600A
Application number: GB1621000.7A
Authority: GB
Inventors: Shepherd Luke; Shepherd Jacob
Original assignee: Haigh Group Ltd
Current assignee: Haigh Group Ltd
Priority date: 2016-12-09
Filing date: 2016-12-09
Publication date: 2018-06-27
Anticipated expiration: 2036-12-09
Also published as: GB201621000D0; GB2557600B

Abstract

A method and device 1 are disclosed for monitoring an electrical apparatus 10 and transmitting data concerning the usage of the electrical apparatus across a network. The device comprises a sensor system configured to monitor instances of a signal changing in a first predetermined manner with respect to a sensor threshold, with resultant generated event data indicating a change of operation state of the electrical device. This change may relate to the apparatus being activated. A store (7, fig. 2) is provided which stores the event data generated during a time window, and a transmitter (3, fig. 2) transmits a representation of the event data to a server across a cellular telecommunications network each time the window elapses. The device further comprises a battery terminal configured to provide electrical power to the device from a battery (4, fig. 2). The signal may be generated by a split core current transformer 8. The device may also comprise a GPRS or 3G modem. The server may extract usage data and store it within a database. The apparatus may be an electric motor which drives a sewage pump.

Description

(71) Applicant(s):

The Haigh Group Limited (Incorporated in the United Kingdom)

Alton Road, Ross-on-Wye, Herefordshire, HR9 5NG, United Kingdom (72) Inventor(s):

Luke Shepherd Jacob Shepherd (74) Agent and/or Address for Service:

Gill Jennings & Every LLP

The Broadgate Tower, 20 Primrose Street, LONDON, EC2A 2ES, United Kingdom (51) INT CL:

G01R 19/165 (2006.01) G01D 4/00 (2006.01) G01R 31/34 (2006.01) (56) Documents Cited:

KR 100891201 B1 US 20130170417 A1

US 20020078173 A1 (58) Field of Search:

INT CL G01D, G01R, G08C, H04W Other: EPODOC, WPI (54) Title of the Invention: Device for monitoring an electrical apparatus Abstract Title: Device for monitoring usage of an electrical apparatus (57) A method and device 1 are disclosed for monitoring an electrical apparatus 10 and transmitting data concerning the usage of the electrical apparatus across a network. The device comprises a sensor system configured to monitor instances of a signal changing in a first predetermined manner with respect to a sensor threshold, with resultant generated event data indicating a change of operation state of the electrical device. This change may relate to the apparatus being activated. A store (7, fig. 2) is provided which stores the event data generated during a time window, and a transmitter (3, fig. 2) transmits a representation of the event data to a server across a cellular telecommunications network each time the window elapses. The device further comprises a battery terminal configured to provide electrical power to the device from a battery (4, fig. 2). The signal may be generated by a split core current transformer 8. The device may also comprise a GPRS or 3G modem. The server may extract usage data and store it within a database. The apparatus may be an electric motor which drives a sewage pump.

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Fig 2

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DEVICE FOR MONITORING AN ELECTRICAL APPARATUS

FIELD OF THE INVENTION

The present invention relates to a device and method for monitoring an electrical apparatus and transmitting data concerning the usage of the electrical apparatus across a network.

BACKGROUND TO THE INVENTION

With the development ofthe so-called Internet of Things (IOT), there is currently a drive towards building increased connectivity into everyday objects thereby enabling them to transmit and share data. An example of this is the roll out of smart meters to UK households. In most instances it has been thought desirable to transmit large quantities of data using telemeters so as to provide a user with live high-resolution data monitored by the telemeter. This has been achievable thanks to recent increases in broadband speeds and the decrease in cost of memory.

Most telemetric devices require a connection to a mains electricity source and transmit high-resolution data across a Wi-Fi (RTM) connection. Access to the mains electricity or a Wi-Fi (RTM) connection cannot always be guaranteed however. Current telemeters that operate instead across cellular telecommunications networks often have prohibitively high running costs associated with them. It is desirable to provide a device which overcomes these problems.

SUMMARY OF THE INVENTION

In a first aspect of the invention there is provided a device for monitoring an electrical apparatus and transmitting data concerning the usage of the electrical apparatus across a network, the device comprising:

a battery terminal configured to provide electrical power to the device from a battery;

a sensor system configured to monitor instances of an electrical signal received via an input changing in a first predetermined manner with respect to a sensor threshold, each instance in which the signal changes in said first predetermined manner generating event data indicative of a change of operational state of the electrical apparatus;

a store configured to store the event data generated during a time window;

a transmitter configured to transmit a representation of the stored event data as an event data set to a server across a cellular telecommunications network each time the time window elapses.

The running costs for a device which transmits data across a cellular telecommunications network are typically dictated by the amount of data that is transmitted. This will also have an impact on the electrical energy that is consumed by the device. By controlling the data that is sent from the device during a time window, the device is able to maintain low running costs and a long battery life. This makes the device particularly well suited for use in remote applications where there is no available access to the mains electricity.

Unlike conventional telemeters, the device does not transmit “live” monitored data. The device instead stores the event data generated during a time window and transmits a representation of the event data each time the time window elapses. By batching the event data as such, the device limits the amount of data that is transmitted and so improves the performance of the device.

The device typically transmits low-resolution, basic information concerning a monitored electrical apparatus. The event data set preferably indicates the number of occasions on which the electrical apparatus was activated during the time window. For example, it may simply include a number indicating how many times the electrical apparatus was switched on during the time window. The event data set is hence only a representation of the event data and typically differs from the event data. In a more sophisticated approach, the event data set comprises characteristics of the signal during each period in which the signal exceeded the sensor threshold. For example, the characteristics may include any or each of the following: a timestamp indicating the time on which change of operational state occurred, the peak signal, the average signal and the length of time for which the signal exceeded the sensor threshold. The characteristics can be used to predict failures of the electrical apparatus, for example from increased current load or overuse of the electrical apparatus. Typically the event data set includes event data corresponding to the instances which occurred during the most recent time window only (prior to transmission), and not from any earlier time windows.

It is desirable to convey information regarding the performance of the device. It is advantageous therefore that the sensor system is further configured to monitor the remaining battery life, wherein the event data set comprises battery life data indicative of the remaining battery life. Similarly, the event data set may further comprise network signal data indicative of the connection strength of the device with the cellular telecommunications network. This enables a person receiving the transmitted event data to replace any batteries within the device, or relocate the device as necessary if the remaining battery life or network signal is low.

The device preferably comprises a battery configured to provide electrical power to the device via the battery terminal. The battery may be replaceable or rechargeable and provides an on-board power source for the device. The device may be able to operate for long periods without needing to be connected to a mains electricity supply. It is desirable therefore that the battery is the only electrical power source for the device.

Typically the sensor system is configured to monitor instances of the signal crossing the sensor threshold. The first predetermined manner may hence correspond to the signal crossing the sensor threshold. Preferably the first predetermined manner corresponds to the signal exceeding the sensor threshold. This provides a simple measure from which the basic information concerning the usage of the electrical apparatus may be obtained.

The signal is typically a voltage, although it could conceivably be a current. Preferably, the sensor threshold is between 1 to 200 millivolts, preferably 2 to 50 millivolts, preferably still 2.5 to 12 millivolts. The sensor system may monitor the signal periodically, preferably every 1 to 20 seconds, more preferably every 5 to 15 seconds, preferably still every 10 seconds.

The device preferably further comprises a current detector electrically connected to the input, wherein the current detector is configured to generate the signal in response to a monitored current. The monitored current is typically an alternating current used to power the electrical apparatus. The current detector may be configured to monitor a current to the electrical apparatus. By monitoring the current flowing to the electrical apparatus, basic information can be obtained regarding the usage of the electrical apparatus.

Typically the current detector is configured such that the signal changes in said first predetermined manner when the current monitored by the current detector changes in a second predetermined manner with respect to an activation threshold. The second predetermined manner may correspond to the current monitored by the current detector exceeding the activation threshold. An electrical apparatus may draw a low standby current when not in use, for example 0.1 amps. The activation threshold is preferably set to be above this standby current but below the normal current that is drawn when the electrical apparatus is in use. Preferably, the activation threshold is between 0.2 to 1.0 amps, most preferably 0.5 amps.

Typically the current detector is a current transformer. These are typically configured to fit around the outside of an electrical cable in order to monitor the current within that cable, without the need for a direct electrical connection to be made. If the monitored current is alternating, a potential difference will be generated across the current transformer due to an electromagnetic interaction. This potential difference provides the signal which is monitored by the sensor system. The current transformer is preferably a split-core current transformer as these can conveniently clip around the outside of a cable.

In order to reduce the amount of data that is transmitted across the cellular telecommunications network the device preferably comprises a processor configured to process the event data into an event data set. The processor may form part of the sensor system, for example in addition to an analogue-to-digital converter. The transmitter may comprise a modem, typically GPRS or 3G modem. The cellular telecommunications network may therefore be a GPRS or 3G network accordingly. These networks generally have excellent coverage and are well suited for when the device is used in remote applications.

The time window selected is typically selected so as to be large enough for a number of potential instances of the signal exceeding the sensor threshold to have occurred, whilst providing useful information reflecting the recent usage of the electrical apparatus. A time window between 12 to 36 hours is preferred, more preferably between 18 to 30 hours, preferably still 24 hours.

In order to improve the battery life of the device and reduce the running costs, it is desirable that the total data transmitted by the transmitter to the server during the time window is low. For example, the event data set may be the only data that is regularly transmitted by the transmitter. Typically the quantity of data in the event data set is less than 10 kilobytes, preferably less than 5 kilobytes, more preferably less than 2 kilobytes.

The total amount of data that is transmitted may depend to some extent on the number of instances for which the signal exceeded the signal threshold within the time window. The device is therefore preferably configured to limit the number of instances from which event data is generated or from which event data is included to the event data set. For example, an upper limit between 20 to 200 instances or 50 to 100 instances may be chosen. This may enable the device to limit the quantity of data in each event data set to below a maximum value, meanwhile maintaining a constant time window. For example a maximum value of 50 kilobytes, 20 kilobytes or 10 kilobytes may be achieved.

The change of operational state which is indicated typically relates to the electrical apparatus being activated. Alternatively it could relate to the electrical apparatus being deactivated. This would still indicate that the electrical apparatus was previously activated; i.e. in use.

Advantageously, the device may be configured such that the event data stored in the store after each time window overwrites the event data in the store corresponding to the previous time window. This enables a store to be used with a relatively small storage capacity, thereby increasing the simplicity of the device and reducing its cost.

In a second aspect of the invention there is provided a system for transmitting usage data from an electrical apparatus across a network, the system comprising:

an electrical apparatus and a device according to the first aspect of the invention;

wherein the electrical apparatus is connected to the device via the input so as to generate said event data in response to a change of operational state of the electrical apparatus.

The second aspect shares similar advantages as discussed with reference to the first aspect. The electrical apparatus can be thought of as a target apparatus from which event data concerning the usage of the apparatus is generated. The electrical apparatus typically requires electrical energy for use. The electrical apparatus may hence be driven by electricity. In a preferred example, the electrical apparatus is an electric motor. Preferably still the electric motor drives a sewage pump. The device is well suited for use with domestic sewage pumps, such as those found with sceptic tanks, where live high-resolution monitored data is not required and where access to mains electricity cannot be guaranteed. Other preferred examples of electrical apparatus include lights and heaters.

The device may conveniently use an already existing electrical circuit, namely that which powers the electrical apparatus, as a source for generating the monitored signal. The device may be retrofitted to this circuit to monitor the current within.

In a third aspect of the invention there is provided a network for monitoring a plurality of electrical apparatus, the network comprising:

one or more systems according to the second aspect of the invention; a server configured to receive the event data sets transmitted by the device(s) across the telecommunications network, wherein the server is further configured to extract usage data from the event data sets and store the usage data within a database.

Advantageously, the server may monitor the behaviour of a plurality of electrical apparatus distributed over a wide area from a central location. This may be useful where the electrical apparatus are licensed to users or where a service agreement is in place regarding the electrical apparatus. The event data sets transmitted to the server may enable an assessment to be made regarding the usage, performance or health of an electrical apparatus using the information stored in the database. It is also possible to use this information to generate invoices to charge users in relation to their use of the electrical apparatus.

The usage data preferably includes the event data and may be the event data set. Alternatively the server may apply transformations to the event data set received before storing it within the database.

It is desirable that the server is configured to send an email to a user based on the usage data. For example, the email may be generated automatically in response to new usage data being stored within the database for an associated device or electrical apparatus. Alternatively the email may be generated periodically. This email may include billing data.

Preferably, the server is further configured to generate a low battery alert based on the received event data sets. This is typically the case where the event data sets include battery life data. Alternatively the battery level may be estimated, for example based on the length of time for which a device has been transmitting data, and a low battery alert generated accordingly. Similarly, the server is preferably further configured to generate a low network signal alert based on the received event data sets. The low network signal alert is typically generated in accordance with network signal data included to the event data set. The low battery alert and/or the low network signal alert may be included to an email that is sent to an associated user of the device. Alternatively these alerts may be used internally by the provider of the electrical apparatus to indicate that maintenance is required.

The database or a portion thereof is preferably accessible to users across an Internet connection to enable easy account access to the user for viewing their usage of the electrical apparatus.

In a fourth aspect of the invention there is provided a method for monitoring the usage of an electrical apparatus comprising:

monitoring instances of a signal changing in a first predetermined manner with respect to a sensor threshold, each instance in which the signal changes in said first predetermined manner generating event data indicative of a change of operational state of the electrical apparatus;

storing the event data generated during a time window;

transmitting a representation of the stored event data as an event data set to a server across a cellular telecommunications network each time the time window elapses.

The signal preferably changes in the first predetermined manner in response to a change of operational state of the electrical apparatus. Furthermore, the method may further comprise monitoring a current to the electrical apparatus and generating the signal in response to said current. This monitoring and generating may be performed by a combination of the current detector and sensor system earlier described.

Each of the features discussed specifically in connection with any of the aspects of the invention are also combinable with the remaining aspects of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be discussed with reference to the accompanying drawings, in which:

Figure 1 is an illustration of a system according to an embodiment;

Figure 2 is a cross-sectional illustration of a device according to an embodiment; Figure 3 is an illustration of a network according to an embodiment; and Figure 4 is a flow diagram illustrating a method performed according to an embodiment.

DETAILED DESCRIPTION

A system for transmitting data from an electrical apparatus 10 across a network is illustrated by Figure 1. The system comprises an electrical apparatus 10 in the form of an electric motor and a battery powered telemetric device 1. The device 1 comprises a current detector 8 in the form of a split core current transformer which is electrically connected to an input socket 11 of the device 1 via flying leads 9, 9’ (which may form a co-axial cable). An electrical circuit comprising cables 2, 2’ carries an alternating current from a power source (not shown) to the motor 10 for operation of the motor 10. The current detector 8 may be connected to either cable 2, 2’ for monitoring the current drawn by the motor 10. In Figure 1 the current detector 8 is clipped around the outside of the cable 2 (including its jacket) to make a physical connection with the cable 2, but not an electrical connection. The alternating current in the cable 2 will induce a potential difference across the current detector 8 through an electromagnetic interaction, which forms an electrical signal that is monitored by the device 1. The current detector 8 is detachable from the device 1 at the input socket 11.

The external housing of the device 1 is visible in Figure 1, whilst the current detector 8 and motor 10 are shown schematically only. The internal components of the device 1, and the input socket 11, are shown in the cross-sectional view of Figure 2. The device 1 comprises a battery source provided by four batteries 4 connected to battery terminals (now shown) of the device 1. The batteries 4 are the sole power source for the device 1, thereby enabling the device 1 to be used remotely where access to mains electricity is not available.

The device 1 comprises a sensor 5, which may be an analogue-to-digital converter, configured to monitor the signal from the current detector 8 and to determine whether this signal exceeds a sensor threshold. The sensor threshold is a voltage chosen so that the signal exceeds the sensor threshold only when the motor 10 is in use. The motor 10 may draw a low “standby current” when not in use, for example 0.1 amps, which increases to a larger “active current”, for example 1 to 10 amps, when the motor 10 is in use. The sensor threshold is selected to correspond to an activation threshold which is a current between the standby current and the active current. The magnitude of the voltage generated by the current detector 8 will depend on the number of coils within the current transformer 8. For example, a sensor threshold of 5.5 millivolts may be chosen, which could equate to an activation threshold of 0.5 amps. Alternatively a sensor threshold of 2.75 millivolts could be chosen to correspond to an activation threshold of 0.25 amps, or a sensor threshold of 11 millivolts could be chosen to correspond to an activation threshold of 1 amp. The signal may have an upper limit of approximately 330 millivolts, corresponding to a current through the cable 2 of 30 amps.

The output from the sensor 5 is periodically monitored by a processor 6, for example every 10 seconds. The processor 6 is configured to generate event data for each instance in which there is a change of operational state between the motor 10 being inactive and active, as indicated by the output from the sensor 5. The sensor 5 and the processor 6 hence form a sensor system configured to monitor instances of the signal exceeding the sensor threshold. The processor 6 is further configured to store the event data in a store 7, which provides a source of non-volatile memory. A volatile memory source (not shown) may also be provided for use with the remaining components of the device 1 in performing steps from the method which is later described.

The device 1 comprises a transmitter 3 configured to wirelessly transmit data from the device 1 across a cellular telecommunications network, such as a GPRS or 3G network. The transmitter 3 comprises a modem with a SIM card and may be configured to automatically connect to the strongest available network. The transmitter 3 is electrically connected to the processor 6 and the store 7.

Figure 3 illustrates a network comprising a plurality of devices 1, 1', 1, each connected to target electrical apparatus as described with reference to Figure 1. The devices 1, T, 1 are configured to transmit data across a cellular telecommunications network 50. The data transmitted from the devices 1, T, 1 across the network 50 is sent to a server 20 via the Internet 40. User terminals 31, 3131 are also connected to the server 20 via the Internet 40.

A method for monitoring an electrical apparatus 10 and transmitting data concerning its usage will now be discussed with reference to the flow diagram of Figure 4 together with Figures 1 to 3. The method begins at step 101 where the sensor 5 monitors a signal in the form of a potential difference across the current detector 8. An event indicative of the electrical apparatus 10 being active occurs whenever the current in the cable 2 exceeds the activation threshold. Through electromagnetic interaction, this causes the signal at the input 11 to exceed the sensor threshold. The sensor 5 monitors the input electrical signal and generates an output accordingly. The output from the sensor 5 is periodically monitored by the processor 6, which generates event data if the signal exceeds the sensor threshold, the event data indicative of the motor 10 being activated.

In a basic embodiment the output from the sensor 5 may be a simple “1” or “0” indicating whether the monitored signal is above or below the sensor threshold. This output is periodically monitored by the processor 6 and event data is generated if the output is “1”. The event data may comprise data concerning the characteristics of the events; i.e. characteristics of the signal during each period in which the signal exceeded the threshold. These characteristics may include a timestamp indicating the time on which change of operational state occurred, the peak signal, the average signal and the length of time for which the signal exceeded the threshold. The event data is stored in the store 7 at step 102.

It is an object of the invention to provide a device 1 with a long battery life and low running costs. A cellular telecommunications network provider will typically charge according to the amount of data which is transmitted across the network 50. The running costs for the device 1 are therefore primarily dictated by the amount of data which is transmitted by the device 1. This will also affect the electrical energy that is consumed by the device 1. In order to improve the performance of the device 1 and reduce the running costs, it is therefore desirable to minimise the amount of data transmitted by the device 1.

At step 103 the processor 6 determines that a pre-determined time window has expired. The method then proceeds to step 104, where the stored event data (corresponding to instances of the signal exceeding the sensor threshold during the time window) is batched by the processor 6 into an event data set for transmission by the transmitter 3. Optionally, the event data may be compressed by the processor 6 at this stage to form the event data set. The time window selected is large enough for a number of potential events to have occurred, whilst providing useful up to date information regarding the usage of the electrical apparatus 10. A regular time window of 24 hours is therefore preferred. This will typically result in each event data set consisting of lowresolution data of less than 4 kilobytes in total, most typically between 0.5 and 2 kilobytes.

Each event could generate additional data to be included to the event data set. The device 1 is therefore configured to enforce a limit on the number of events detected during the time window from which event data is generated, or from which event data is included to the event data set. This limits the total amount of data within the event data set to a level which ensures the performance of the device and its running costs are not unduly worsened as a result of an exceptionally high level of use of the motor 10. For example, a limit of 50 events may be selected. This will typically limit the total data within the event data set to less than 10 kilobytes. The total number of events detected during the time window may be counted and included to the event data set. In order to limit the total data within the event data set, the characteristics from only a limited number of events (e.g. 50 events) may be included to the event data set.

The processor 6 is configured to monitor the remaining battery life for the batteries 4, as well as the connection strength of the device 1 with the cellular telecommunications network 50 each time the time window elapses. This information is quantified as a number (typically ranging from 0 to 5) and included in the event data set as battery life data and network signal data respectively.

At step 105 the event data set is transmitted from the transmitter 3 across the cellular telecommunications network 50 as one or more packets, typically in binary form, each time the time window elapses. The event data set may include a first portion indicating a serial number for the device, the number of events that occurred during the time window, the battery life data and the network signal data. A subsequent portion of the event data set may comprise more detailed information concerning the characteristics of each of the events.

For example, the first portion of the transmission might consist of a packet showing [452435, 20, 5, 5] indicating that device serial number 452435 monitored that the motor 10 was activated 20 times in a day, the device having full battery charge and a full network signal strength at the time the packet was transmitted. In the embodiment described above where the output from the sensor 5 is either a “0” or a “1”, the number of the times in which the motor 10 is activated is estimated from the number of times in which the output from the sensor 5, as periodically monitored by the processor 6, transitions from “0” to “1” during the time window. In the subsequent portion, a further 20 packets may then follow with characteristics of the monitored signal for each period in which this signal exceeded the threshold. Each packet may comprise a timestamp indicating when the current exceeded the threshold, the length of time for which the current exceeded the threshold, the average current and the peak current. For example, the packet [14/09/2016 15:10, 120, 1.3, 1.8] could show that the motor 10 was activated on 14/09/2016 at 15:10, the motor 10 was active for 120 seconds, the average current drawn by the motor 10 during that time was 1.3 amps and the peak current during that time was 1.8 amps. By selectively outputting the event data as such, it has been found that a battery life of 27 months can be obtained from four “C” cell batteries 4.

Once the event data set is transmitted by the transmitter 3, the processor 6 erases the event data set and any corresponding event data from the store 7 so as to provide additional storage for subsequent event data to be stored. This is step 106. Optionally the event data from a previous time window may be erased before any event data corresponding to a new time window is stored. Alternatively the event data from a new time window may simply overwrite the event data from a previous time window as it is generated and subsequently stored. Steps 101 to 106 then repeat for subsequent time windows.

The packets which are transmitted by the devices 1, T, 1” across the GPRS network 50 are received by the server 20 via the Internet 40. The server 20 reads the event data sets from the packets and extracts usage data from the event data sets. The usage data may comprise the event data and indicates the usage of the electrical apparatus monitored by each of the devices 1, T, 1”. At step 107 the usage data is stored within a database stored in non-volatile memory on the server 20. The database typically provides a list of different electrical apparatus 10 and associated data regarding their usage provided by the corresponding device 1, T, 1”. The database may further comprise the battery life data and the network signal data associated with each of the devices 1, T, 1”.

The server 20 is configured to periodically perform a review of the database, for example every 24 hours. If the usage data indicates that an electrical apparatus 10 has been used during those 24 hours, a report may be automatically generated and emailed to a client at step 108 using an email address obtained from account information that is associated with the electrical apparatus 10. The battery life data and the network signal data may optionally be included to the report. This email is transmitted across the Internet 40 to a user terminal 31, 31’ 31”. The server 20 may also generate an alert, for example in the form of an email, if the battery life data or the network signal data is low (e.g. for values of 0 or 1). The alert may hence correspond to a low battery alert or a low network signal alert.

The information stored in the database may further enable an assessment to be made regarding the usage, performance or health of an electrical apparatus. It can further be used to indicate when maintenance of an electrical apparatus or the associated device is required. For example, the characteristics included in the event data set may indicate that the peak or average monitored current is above an acceptable level, which may suggest that failure of the electrical apparatus is likely to soon occur.

The device 1 is particularly well suited for monitoring electrical apparatus which are switched on and off one or more times a day (e.g. an electric motor, light or heater) and for which high-resolution information is not required. One such example is where the electrical apparatus comprises an electric motor which drives a pump, such as a sewage pump, for example for use in a septic tank.

Sewage pumps in septic tanks are typically run based on the levels of fluid in a tank and therefore are variable based on factors such as rainfall. The pumps themselves are typically low cost and therefore do not warrant high resolution, high cost monitoring devices where low resolution device will suffice.

As will be appreciated, the device 1 provides a simple solution for transmitting data concerning the usage of an electrical apparatus 10 without the need for the device 1 to have access to a mains electricity supply. A long battery life and low running costs are obtained as a result of the method of data processing and transmission that occurs at the device 1.

Claims

1. A device for monitoring an electrical apparatus and transmitting data concerning the usage of the electrical apparatus across a network, the device comprising:

a store configured to store the event data generated during a time window;

2. A device according to claim 1, wherein the event data set indicates the number of occasions on which the electrical apparatus was activated during the time window.

3. A device according to claims 1 or 2, wherein the event data set comprises characteristics of the signal during each period in which the signal exceeded the threshold.

4. A device according to claim 3, wherein the characteristics include any or each of the following: a timestamp indicating the time on which change of operational state occurred, the peak signal, the average signal and the length of time for which the signal exceeded the threshold.

5. A device according to any of the preceding claims, wherein the sensor system is further configured to monitor the remaining battery life and wherein the event data set comprises battery life data indicative of the remaining battery life.

6. A device according to any of the preceding claims, wherein the event data set further comprises network signal data indicative of the connection strength of the device with the cellular telecommunications network.

7. A device according to any of the preceding claims, further comprising a battery configured to provide electrical power to the device via the battery terminal.

8. A device according to any of the preceding claims, wherein the first predetermined manner corresponds to the signal exceeding the sensor threshold.

9. A device according to any of the preceding claims, wherein the signal is a voltage.

10. A device according to claim 9, wherein the sensor threshold is between 1 to 200 millivolts, preferably 2 to 50 millivolts, preferably still 2.5 to 12 millivolts.

11. A device according to any of the preceding claims, wherein the sensor system is configured to monitor the signal periodically, preferably every 1 to 20 seconds, more preferably every 5 to 15 seconds, preferably still every 10 seconds.

12. A device according to any of the preceding claims, further comprising a current detector electrically connected to the input, wherein the current detector is configured to generate the signal in response to a monitored current.

13. A device according to claim 12, wherein the current detector is configured to monitor a current to the electrical apparatus.

14. A device according to claims 12 or 13, wherein the current detector is configured such that the signal changes in said first predetermined manner when the current monitored by the current detector changes in a second predetermined manner with respect to an activation threshold.

15. A device according to claim 14, wherein the second predetermined manner corresponds to the current monitored by the current detector exceeding the activation threshold.

16. A device according to claims 14 or 15, wherein the activation threshold is between 0.2 to 1.0 amps, preferably 0.5 amps.

17. A device according to any of claims 12 to 16, wherein the current detector is a current transformer, preferably a split-core current transformer.

18. A device according to any of the preceding claims, further comprising comprises a processor configured to process the event data into an event data set.

19. A device according to any of the preceding claims, wherein the transmitter comprises a GPRS or 3G modem.

20. A device according to any of the preceding claims, wherein the time window is between 12 to 36 hours, preferably between 18 to 30 hours, preferably still 24 hours.

21. A device according to any of the preceding claims, wherein the quantity of data in the event data set is less than 10 kilobytes, preferably less than 5 kilobytes, more preferably less than 2 kilobytes.

22. A device according to any of the preceding claims, wherein the device is configured to limit the number of instances from which event data is included to the event data set.

23. A device according to any of the preceding claims, wherein the change of operational state relates to the electrical apparatus being activated.

24. A device according to any of the preceding claims, the device configured such that the event data stored in the store after each time window overwrites the event data in the store corresponding to the previous time window

25. A system for transmitting usage data from an electrical apparatus across a network, the system comprising:

an electrical apparatus and a device according to any of the preceding claims;

26. A system according to claim 25, wherein the electrical apparatus is an electric motor.

27. A system according to claim 26, wherein the electric motor drives a sewage pump.

28. A network for monitoring a plurality of electrical apparatus, the network comprising:

one or more systems according to any of claims 25 to 27; a server configured to receive the event data sets transmitted by the device(s) across the telecommunications network, wherein the server is further configured to extract usage data from the event data sets and store the usage data within a database.

29. A network according to claim 28, wherein the server is configured to send an email to a user based on the usage data.

30. A network according to claims 28 or 29, wherein the server is further configured to generate a low battery alert based on the received event data sets.

31. A network according to any of claims 28 to 30, wherein the server is further configured to generate a low network signal alert based on the received event data sets.

32. A method for monitoring the usage of an electrical apparatus comprising: monitoring instances of a signal changing in a first predetermined manner with respect to a sensor threshold, each instance in which the signal changes in said first predetermined manner generating event data indicative of a change of operational state of the electrical apparatus;

storing the event data generated during a time window;

transmitting a representation ofthe event data as an event data set to a

5 server across a cellular telecommunications network each time the time window elapses.

33. A method according to claim 32, wherein the signal changes in the first predetermined manner in response to a change of operational state of the

10 electrical apparatus.

34. A method according to claims 32 or 33, further comprising monitoring a current to the electrical apparatus and generating the signal in response to said current.

Intellectual

Property

Office

Application No: GB 1621000.7