The present invention is directed to a plug for attachment to for example the mains cable of an electrically operated device, the plug including safety features.

Electrically operated devices may be arranged to receive power from a battery, an electricity generator, or from a general purpose alternating current electric power supply generally referred to as mains power in the UK and by a variety of names elsewhere: in the US for example mains electricity may be referred to as household power, household electricity house current, powerline, domestic power, wall power, line power, AC power, city power, street power and grid power. For the purposes of the present document it will be referred to as mains power. Where the device relies on receiving power from the mains, electrical power is generally delivered through a cable which is, at a first end, either hard wired to the device or otherwise engaged thereto, and at a second end includes a means to interface with the mains, such as a plug.

Mains electricity provides electrical energy at, in some countries such as the UK, an electromotive force (EMF) of 240 volts, and in other countries of the order of 110 to 120 volts. The large currents associated with the supply of such voltages can give rise to a heating effect for example in or adjacent the plug or in the electrically powered device, and this is a common cause of domestic, industrial, business or other fires leading to damage, expense and, more importantly, loss of life.

Conventional safety devices are available that provide an alert when conditions associated with a fire are detected, such as smoke alarms that detect the presence of smoke generated in the first stages of a fire. Such safety devices are helpful to provide opportunities for residents, workers or others to escape the effects of a fire, and to alert the relevant authorities to take action to fight the fire, but damage to at least the building and possessions is usually inevitable.

What is needed is a means to alert residents, workers or others when the conditions that may lead to a fire occur, so that a fire can be avoided. The present invention provides, in accordance with a first aspect, a safety plug for attachment to an electrically operated device's power source cable, including protruding pins for engagement with the contacts of a mains socket-outlet, the pins adapted to securely engage with respective wires of the mains cable, at least one temperature sensor, and an alarm mechanism, the alarm mechanism engaged with the at least one temperature sensor and adapted to initiate an alarm when the temperature sensor detects a temperature above a predetermined threshold.

Preferably the safety plug further comprises a first portion including the pins and a second portion including the alarm mechanism, wherein at least one of the at least one temperature sensor is positioned in the second portion.

Preferably the safety plug further comprises a first portion including the pins and a second portion including the alarm mechanism, wherein at least one of the at least one temperature sensor is positioned in the first portion.

Preferably the temperature sensor is positioned between two of the pins.

Preferably the at least one temperature sensor and alarm are connected to, and powered by, an extra low voltage supply.

Preferably the extra low voltage is less than 50 volts

Preferably the extra low voltage is less than 9 volts

Preferably the extra low voltage is between 3 and 6 volts.

Preferably the second portion includes a fuse of between 0.5 - 1 A.

Preferably the second portion includes a light source which is activated to shine a light while the extra low voltage is powering the temperature sensor and alarm.

Preferably the light source is positioned on an external surface of the safety plug.

Preferably while active, the light shone by the light source is green. Preferably the second portion includes a temperature indicator light source which is activated to shine an alarm light when a temperature detected by the at least one temperature sensor exceeds a predetermined temperature.

Preferably the temperature indicator light source is positioned on an external surface of the safety plug.

Preferably the temperature indicator light source shines a red light.

Preferably the temperature indicator light source shines a flashing light.

Preferably the second portion includes a sound generator which is activated to issue an aural alarm when a temperature detected by the at least one temperature sensor exceeds a predetermined threshold.

Preferably the sound generator issues a buzz.

Preferably the second portion also includes at least one auxiliary socket.

Preferably the at least one auxiliary socket is positioned on an external surface of the plug.

Preferably the at least one auxiliary socket is connectable to a remote temperature sensor.

Preferably the remote temperature sensor is positionable adjacent a device powered by the cable.

Preferably the at least one auxiliary socket comprises a communication socket to initiate a remote alarm when a detected temperature exceeds a predetermined threshold.

Preferably the safety plug further comprises a remote sensing device through which said electrically powered device connects to said plug.

Preferably said remote sensing device is remote said plug and connected thereto by a cable. Preferably said remote sensing device is positionable within said electrically powered device.

Preferably said remote sensing device includes at least one temperature sensor.

Preferably said at least one temperature sensor positioned at an end of a lead.

Preferably said at least one temperature sensor is connectable to and communicable with a fire alarm system.

Preferably the second section includes a test button for confirming functionality of the sensors and alarms.

Preferably the second section includes a circuit protection device to, when initiated, protect the circuit from overheating or short circuit.

Preferably either of the test button or circuit protection device is positioned on an external surface of the plug.

The present invention provides, in accordance with a further embodiment, an electrically operated device including a mains cable attached to a safety plug as disclosed above.

Preferred embodiments of the present invention will now be described by way of example only and with reference to the accompanying drawings in which:

Figure 1 shows a first side of a plug in accordance with a first embodiment of the present invention,

Figure 2 shows a second, opposite side of the plug of Figure 1, showing an internal cross sectional view of a first portion, and

Figure 3 shows the second side of the plug of Figure 1 with a cover attached. Figures 4 (a) - (d) show a front, a back, a side and a perspective view respectively of an alternative version of the plug of Figure 1.

Figure 5 (a) shows a second embodiment of the present invention, including a remote sensing device positionable within an electrically operated device, and

Figure 5 (b) shows the remote sensing device of Figure 5 (a) positioned within an electrically operated device.

A plug 1 in accordance with a first embodiment of the present invention may be seen from a first side in Figure 1. The plug comprises a first 10 and a second 20 portion.

The first portion 10 is similar to the arrangement of a conventional plug, with, in the present case, three pins 11, 12 and 13 extending outwardly away from the body of first portion 10 and a mains cable 14 extending away from a base section of the first portion 10 for engagement with for example an electrically powered device (not shown). The three pins are conventionally adapted for location in a socket, for engagement with a mains power supply, to provide power to for example the electrically powered device (not shown).

Figure 1 also shows a central screw 15 for connection of a rear cover of the plug to the body of the plug, and further screws 16 to further secure the cover of the plug to the body of the plug. Such screws are optional any other means may be utilised to secure the cover to the body of the plug.

The second portion 20 of the plug is shown to extend away from the first portion 10 in a direction opposite that of the mains cable, although any direction is contemplated to be covered by the present invention, and includes an information plate 21 where for example technical information relating to the plug may be located. Two further screws 22 may be seen towards the top of the second portion of the plug, also for securing a cover to the body of the plug. Although the presence of such screws is optional as alternative means may be employed to attach the plug components together. On the second portion, between the screws 22, where present, may be positioned a 'buzzer vent' 23 to allow any noise generated within portion two 20 of the plug to be heard outside the plug.

Figure 1 also shows two auxiliary sockets 24, 25 positioned on a side surface of portion two of the plug, although the auxiliary socket positions are not limited to a side of the plug body, they may be placed in any convenient location on the plug.

Figure 2 shows a cross sectional view of a second, opposite side of the plug of Figure 1, revealing the internal architecture of the first portion. As can be seen the arrangement of the first portion of the plug is largely conventional, including seating for the three pins 11, 12 and 13, screws 15, 16, and also showing a conventional securing mechanism 18 for the mains cable. Figure 2 also shows a conventional fuse 19.

Positioned within the first portion of the plug may also be seen a temperature sensor 50, with wires 51 attached thereto and passing into the second portion 20 of the plug 1. It is contemplated that wires 51 may be contained within a wall of the plug body (not shown) so they are not visible or accessible when removable cover 17 (not shown in Figure 1) is removed. As can be seen the temperature sensor 50 is positioned adjacent one of pins 11, 12, 13 and it is contemplated that it may be positioned anywhere in the first section, for example between two of the pins (not shown).

Figure 2 also shows the second portion 20 of the safety plug 1 with a cover 26. The interior of the second portion of the plug is broadly conventional however it is contemplated that the second portion will be inaccessible to users.

Several features of the second portion 20 of the plug may be seen in Figure 2, including an activity monitor light 52, a temperature indicator (alarm) light 53, a buzzer alarm 54, a test button 55, and a circuit protection device 56. Figure 2 also shows the first 24 and second 25 auxiliary sockets shown in Figure 1, in accordance with a first embodiment, positioned on a side of the plug body.

Figure 3 shows the plug of Figure 2 with cover section 17 covering the first portion 10 of the plug 1 and cover 26 covering the second portion 20 of the plug 1, with the monitor light 52, alarm light 53, buzzer alarm 54, test button 55 and circuit protection device 56 positioned thereon. Figure 3 also shows the first 24 and second 25 auxiliary sockets positioned on a side wall of the plug body, as in Figures 1 and 2.

Figures 4 (a) to 4 (d) show views of an alternative arrangement of the plug of Figure 1. In particular Figure 4 (a) shows a view of cover sections 17, 26 of a plug, with a test button light 55, power indicator light 52, and alarm indicator light 54 positioned thereon, and cable 14 extended away. Figure 4 (b) shows the reverse side of the plug of Figure 4 (a), with three pins, 11, 12, 13 extending outwardly away from a lower section of the body of the plug, with central screw 15, and a buzzer vent 23 on an upper section of the plug.

Figure 4 (c) shows a side view of the plug of Figure 4(a), showing pins 11, 12, 13, lights 52, 54, 55 and also auxiliary sockets 24, 25. Figure 4(d) shows a perspective view of the plug of Figure 1.

As stated, power supplied from the mains to the plug is directed to an electrical device through a mains cable 14, and in addition in the present case power is also directed into the second portion of the plug to conventionally provide an extra low voltage (ELV) to features in the second portion of the plug such as the activity monitor light 52, temperature indicator (alarm) light 53, buzzer alarm 54, test button 55, and circuit protection device 56. It is contemplated that the ELV will provide less than 50 volts: it is further contemplated that the ELV may provide less than 9 volts, perhaps between 3 and 6 volts. The circuit protection device 56 may be a conventional thermal cut-out or a fuse of for example 0.5 - 1 Amps, although other arrangements may be suitable and fall within the scope of the present invention. This is an important safety feature of the plug.

The activity monitor light 52 will remain illuminated while the safety plug is connected to the mains and receiving power, and it is contemplated that the activity monitor light 52 provides a green light. As stated, ELV power is also supplied to alarm light 53, alarm buzzer 54, test button 55 and, when present, circuit reset button 56. Thus a user can be reassured that provided the safety plug shows a green light the device is powered and monitoring the temperature of the plug, and that should the temperature sensor, or one of the temperature sensors, detect that a temperature has reached or exceeded a threshold an alarm will be triggered. In addition, a user wishing to confirm or establish what an alarm will look or sound like can press the test button to find out.

Should the ELV fuse blow, the activity monitor light will cease to work, alerting users that the safety features of the plug are not active. The second portion of the plug is adapted so that the fuse can be replaced by conventional means without a user needing to gain access to the second portion of the plug.

In use, with a safety plug in accordance with the present invention attached to the power cable of an electrically powered device, the plug may be inserted into a mains socket and a socket switch, if present, set to On' to provide mains power to the plug. The activity monitor light 52 will be seen to show a green light by a user, thereby providing reassurance that the safety plug is powered and working. If the user wishes to test any alarms available in the plug, the test button 55 may be activated, in response to which the alarm light 53 will shine for example a red light, which may, if the safety plug is suitably arranged, flash, and the aural alarm, for example buzzer 54, may sound, perhaps through vent 23. The alarms will cease once the test button is released.

Temperature sensor 50 in the first portion of the plug will proceed to monitor the temperature of the plug. The particular temperature sensor 50 used in the plug is selected based on the temperature threshold considered suitable for the arrangement. Generally it is expected that a temperature within the plug that is below 45°C, or perhaps below 40°C, is suitable and safe, whereas a temperature that exceeds this threshold may indicate a problem is developing. The particular sensor selected will also depend on where, in the plug, the sensor is to be positioned. For example where the sensor is to be positioned between the pins of the plug a particular temperature sensor would be deemed suitable, whereas if the sensor is positioned elsewhere in the plug a slightly different sensor may be selected. The temperature sensor selected for placement in the plug is likely to be a sensor with a threshold of 45°C, or perhaps 40°C, however other temperatures are contemplated, for example for other circumstances, and fall within the scope of the present invention. Should the temperature detected by the temperature sensor within plug 1 exceed the threshold, the safety plug is adapted in a conventional manner to initiate the or all the alarms in the plug, including for example the visual alarm of alarm light 53 and the aural alarm or buzzer 54. Such alarms will draw attention to the plug and the developing problem so that action can be taken, i.e. the plug removed from the socket, and investigations carried out, before a fire develops.

In other embodiments a temperature sensor may be placed in a location remote from the plug, for example a temperature sensor may be attached to one end of a lead, the other end of which is inserted into one of the auxiliary sockets 24, 25. The temperature sensor may then be attached to the device which is powered via the plug. For example if the powered device is a dishwasher, lap top, microwave or other suitable device, the remote temperature sensor may be secured upon or attached to the dishwasher, laptop, microwave or other suitable device. This has the advantage that when the device is powered by the plug such a sensor will monitor the temperature at the device, and provide an alert should the temperature at the device rise beyond an expected or desired level.

Figure 5 shows a second embodiment of the present invention, in particular showing remote sensing device 100 for connection to a plug 20, via cable 14 and designed to be installed within a device such as a washing machine, dishwasher, freezer or other electricity powered device. The remote sensing device 100 transfers power to the electricity powered device through a further cable 102, meaning that the remote sensing device is connected between the plug 20 and an electric powered machine.

Remote sensing device 100 utilises the power supplied not only to power the electrically operated device but in addition provides additional sensing capabilities to the arrangement. As can be seen the device of Figure 5 has two sensors 104, 106 connected to the remote sensor by leads 103, 105, and these sensors may be positioned distal the remote sensing device at positions around the interior of the electrically operated device. This has the advantage that the two remote sensors are capable of detecting an increase in temperature beyond an expected temperature within the device, when the device is in use. It is contemplated that more or less than two sensors may be positioned in this manner.

The remote sensing device 100 has a further feature, shown in Figure 5 (a) as third sensor 108, which may be integrated with for example a fire alarm system 110 installed at the location where the electrically operated device is in use. Should the sensor detect a temperature outside an expected range, the fire alarm system will react. It may be that the fire alarm system will set of an alarm, or it may send a message to a mobile phone, to the police or fire services, or it may communicate the situation by some other means.

In addition, the remote sensing device 100 includes a light 130 on an exterior surface which shines when power is received by the remote sensing device, i.e. when the device is active. The remote sensing device 100 also includes a reset button 140 which may be used to reset the device should an error occur.

Figure 5 (b) shows the remote sensing device of Figure 5 (a) in situ in a washing machine 120 in a domestic setting. The remote sensing device 100 is shown positioned within the device 120 and connected with plug 20 via cable 14. The remote sensing device 100 engages with the electrically operated device 120 via further cable 102. Cables 103, 105 with respective sensors 104, 106 mounted at an end remote the remote sensing device 100 but connected thereto are shown positioned in an internal space of the device 100, and further sensor 110, mounted at a distal end of cable 108, is shown connected to a fire alarm system in operation at the location of the electrically operated device.

The presence of the remote sensing device 100 is not apparent to a user, but provides an additional level of security, protecting the users when the device is in use by issuing an alert if the temperature detected is outside an expected or desired range.

It is expected that the fire alarm system will be a wireless arrangement, although alternatives are contemplated and fall within the scope of the invention. In general when considering remote sensors, i.e. those placed away from the plug for example, the type sensor (i.e. the temperature range it is designed to detect) should be selected such that the temperature threshold is suitable for the device to be monitored and the position in which the temperature sensor is to be placed. The further the temperature sensor is placed from a likely location of a temperature increase, the lower the temperature threshold should be due to the likely dissipation of heat between the heat source and the sensor, and this should be reflected in the temperature threshold of the sensor. Thus should the powered device develop a fault resulting in an unexpected rise in temperature the alarm(s) will be triggered.

Such a fault may arise if for example a device such as a mobile phone, or tablet, is left charging overnight or for a long period of time - in such circumstances a user may not be in the same room, or may be asleep, and be unaware that the device is in danger of overheating. It is often the case that users are unaware that an electric device left charging for long periods might overheat. In addition, it is often the case that washing machines or dishwashers are set to switch on during the night so users can benefit from low cost electricity tariffs, unaware of the dangers posed by such machines developing faults or overheating while they sleep. With a remote sensor device positioned within such a machine, an alarm will be triggered should an unexpected temperature be detected.

An advantage of having an ELV supply to the second portion of the plug is that the remote sensor will be powered by the ELV, meaning that the connecting cable, while providing power, will not provide power at 240 volts, making it a much safer arrangement.

Thus a safety plug in accordance with the present invention is adapted to generate an alarm should the plug itself or a device powered by the plug overheat, leading to the possibility of a fire. Once the alarm has been initiated a user has the opportunity to remove the plug from the socket, thereby removing the source of power, and investigate the cause of the alarm, for example whether the cause of the alarm is within the plug itself or the device powered by the plug. Where a remote sensor device is installed within an electrically operated device and the remote sensor is integrated with a fire alarm system, the fire alarm panel or message sent is capable of indicating exactly the device causing concern, or the location of the temperature increase in the building.

It is contemplated that the plug can be adapted to record all occasions in which an alarm has been triggered. This provides a 'paper trail' should one be needed, showing the history of the behaviour of the safety plug, the powered device, and those responsible for reacting to any alarms that occur. This can be useful in training, in monitoring devices, and in monitoring the behaviour of responsible parties to ensure safety protocols are observed. Such recording can occur remote from the plug, perhaps utilising for example one of the auxiliary sockets in a conventional manner.

The safety plug is adapted to ensure, as far as possible, that no 'false alarms' occur, in particular transmission noise may be discounted, and this is assisted by ensuring that the components from which the plug is made are adapted for 240 volts. This also enhances the robustness of the plug. In the event that a temperature rise occurs that is sufficient to set off an alarm, the safety plug provides an opportunity for an investigation to be carried out: if no immediate problem is found action may be taken to identify why the temperature threshold has been breached. By this means potential problems can be identified very early and action taken to ensure they do not develop further.

Thus the safety plug is adapted to initiate an alarm should a temperature in the plug exceed a predetermined threshold, and additionally may also initiate an alarm should a temperature in for example a device powered via the plug exceed a predetermined threshold. Detecting such incidents can ensure that fires that might otherwise occur can be avoided by taking suitable action to remove the plug from the mains and investigate why the heating effect has occurred, so that no further incidents arise; or by investigating why an electrically operated device such as a dishwasher, washing machine etc has triggered an alarm, and taking action to disconnect the machine from the mains. The safety of domestic, industrial, work and other environments is thereby enhanced. In addition, of course, the safety plug may be used with an extension lead or socket, and provides a means by which any overloading of the extension lead or socket may be detected.

An advantage of the present safety plug is that it may be fitted by a lay person as well as an electrician; also the remote sensing device may also be connected to a fire alarm system by a lay person as well as an electrician. In addition, an electrically powered device may be sold with the safety device already fitted thereto.

The invention is not restricted to the details of the foregoing embodiments. For example the buzzer vent may be positioned anywhere on the plug; the auxiliary sockets may be positioned anywhere on the plug, including on the same side of the plug, or on opposite sides of the plug. The position of the activity monitor 52, alarm light 53, aural alarm 54, test button 55, and circuit protection device 56 may be varied in particular they may be positioned in any suitable position on the plug body. In addition it is contemplated that these monitors, alarms and buttons may be controlled via one of the auxiliary sockets. The test button and circuit protection device may be any sort of switch or controller and are not limited to buttons. The present disclosure mentions two auxiliary sockets but it is contemplated that a different number be relied upon, either one, or several, as required. While only one external sensor has been disclosed, positioned on an electric device, there may be more than one such external sensor, for example for positioning in different places remote from the plug. The information plate shown on Figure 2 is optional, or may be placed elsewhere on the plug. The arrangement or number of screws to fix a cover to the plug body may be varied. The ELV arrangement may provide power to all the features in the second portion of the plug, or may provide a standard amount of power to this portion of the plug, with ELV provided to selected features.