Heat sensor assembly and method for power distribution systems

Abstract

This invention discloses a thermal sensor assembly for a power distribution system. The assembly includes: a cable comprising a plurality of at least three thermal sensors arranged along the length of the cable, each thermal sensor spaced apart from the next thermal sensor by a gap; an end module located at a first end of the cable, the end module having corresponding plurality of terminal pairs, each terminal pair dedicated to one of the thermal sensors; circuitry located within the cable connecting each of the thermal sensors to a corresponding pair of the terminal pairs, such that each terminal pair outputs a temperature signal indicating the temperature sensed by the corresponding thermal sensor; and a controller configured to receive the temperature signal from each terminal pair and compare the temperature signals to determine whether the temperature sensed by any one of the thermal sensors differs from the temperature sensed by the other thermal sensors by more than a predetermined threshold (ΔTALARM), and if so, generate an alarm signal.

Description

Technical Field

[0001] This invention relates to thermal sensor assemblies, thermal sensing systems comprising multiple such assemblies, and thermal sensing methods, all applicable to power distribution systems. The invention also relates to power distribution systems incorporating such thermal sensor assemblies and groups of busbar segments for such systems. Prior Technology

[0002] Bus ducts or overhead bus trunking are becoming a widely used power distribution method in various commercial buildings. This allows for fast and flexible point-to-point power distribution and enables the placement of taps at different points and the reconfiguration of the system layout, which is more efficient than using standard cables. It also eliminates the need for containment installations for cabling.

[0003] There are many manufacturers of such busbar conduit systems worldwide, and all of them have very similar designs. A typical system consists of a metal box-shaped conduit structure with conductor strips inside. These are usually manufactured in preset lengths of about 3 to 4 meters, and they are interconnected via custom-made connector components or simply plugged into each other using a male-to-female plug / socket method. Prefabricated angles and T-shaped fittings are also manufactured, allowing for the rapid installation of complex systems.

[0004] One problem with all these systems is weight. Busbar conduit components are bulky, accommodating up to four copper-aluminum busbars rated for currents ranging from 25A to 6300A. For shorter systems, this weight can range from tens of kilograms to hundreds of kilograms for larger systems.

[0005] As with any system, joints are the weakest points and are often the areas that require attention in the event of a failure. In a typical busbar conduit distribution system, there are numerous joints, such as between any two busbar conduit segments and between busbar conduit segments and taps.

[0006] Due to the system's weight, it requires extremely careful and robust support. Busbar conduit segments are typically attached to the surrounding steel structure or the building structure itself. Over time and under extreme temperatures, this support structure can and does shift, putting stress on the joints, weakening them, and causing damage to electrical connections. These supports can also stretch if the wrong materials are used or insufficient support is provided, which can similarly damage the joints. In all cases, when joints shift and become damaged, they generate heat, and undetected heat can lead to equipment shutdown or, in the worst case, a catastrophic system failure, resulting in prolonged organizational downtime. For example, such downtime can result in hundreds of thousands of dollars in losses annually for a typical organization.

[0007] Currently, there is no definitive method for continuously monitoring damaged joints in busbar conduit systems. To date, the only method for inspecting the system's condition is through visual inspection or the use of thermal imaging. This leads to numerous problems, such as time-based inspections (typically performed annually) and variations in load. A simple visual inspection from the ground does not always allow users to detect sagging or bending in the structure.

[0008] There are also fiber optic-based systems for fire detection or leaky pipe inspection. These systems utilize Raman scattering, involving emitting laser signals along the entire length of the fiber, causing some of the light to scatter and reflect back to the controller unit. This scattering changes with temperature, allowing a temperature profile to be established along the fiber. These systems are expensive and are typically used for fire detection in submarine cables, large pipeline systems, oil and gas distribution, and tunnels. Such systems are unsuitable for detecting damaged joints in busbar conduit power distribution systems because they are very expensive (approximately $40,000 for a 1000-meter system), complex to configure and commission, bulky, and each controller requires rack-mount space.

[0009] Therefore, it is hoped that solutions can be provided to overcome at least some of these shortcomings. Summary of the Invention

[0010] A first aspect of the present invention provides a thermal sensor assembly for a power distribution system, comprising: A cable comprising a plurality of at least three thermal sensors arranged along the length of the cable, each of the thermal sensors being spaced apart from the next thermal sensor by a gap; An end module, located at the first end of the cable, has a corresponding plurality of terminal pairs, each terminal pair dedicated to one of the thermal sensors; A circuit, located within the cable, connects each of the thermal sensors to a corresponding pair of the terminal pairs, such that each terminal pair outputs a temperature signal indicating the temperature sensed by the corresponding thermal sensor; and The controller is configured to receive the temperature signal from each terminal pair and compare the temperature signals with each other to determine whether the temperature sensed by any one of the thermal sensors differs from the temperature sensed by the other thermal sensors by more than a predetermined threshold (ΔTALARM), and if so, generate an alarm signal.

[0011] This type of thermal sensor assembly provides an easy-to-install, easy-to-use, and low-cost solution for detecting damaged joints in power distribution systems formed by busbar conduits. The cable containing the thermal sensor can be attached to the exterior of the busbar conduit housing (e.g., via cable ties or clamp assemblies), allowing for direct retrofitting of existing power distribution systems, or it can be installed inside the busbar conduit, for example, during system installation. The assembly leverages the fact that if all joints are functioning properly, their temperatures should be approximately equal. However, if a joint is damaged (e.g., loose or even open), excessive heat will be generated locally, increasing the temperature of that joint relative to others. The thermal sensors can be installed near different joints in the power distribution system. A controller (which can be included in an end module or provided remotely) then compares the temperature signals from each thermal sensor, generating an alarm if the temperature difference between one sensor and the others exceeds a preset threshold (ΔTALARM). This allows system operators to be alerted to damaged joints virtually immediately upon the occurrence of a fault, rather than waiting for annual inspections. In this way, faults can be quickly repaired, avoiding costly downtime.

[0012] This circuit can be implemented in various ways. In a particularly preferred embodiment, the circuit includes a plurality of corresponding measurement lines and a common return line, each of the measurement lines connecting one of the thermal sensors to a first terminal of a corresponding terminal pair in the end module, and the common return line connecting each of the thermal sensors to a second terminal of a corresponding terminal pair in the end module. This approach minimizes the number of core wires that the cable needs to carry, thus allowing the use of relatively small diameter cables.

[0013] This circuit can be provided, for example, by using any form of multi-core cable that provides at least the number of lines required to obtain each temperature signal. For instance, a 7-core cable (approximately 6 mm in diameter) can be used, with each thermal sensor connected to the relevant two cores at appropriate points along the cable length. Alternatively, standard CAT5 or CAT6 patch cords can be used to form at least a portion of the connection cable between the thermal sensors.

[0014] The controller can be implemented using firmware, hardware, or software (or any combination thereof) and is typically provided on a local card to which the terminal pairs are connected (e.g., via connectors that can be coupled and decoupled, or via hardwired terminal strips), but in other cases, the controller may be located at a remote location. Determining whether the temperature sensed by any one thermal sensor differs from the temperature sensed by other thermal sensors by more than a predetermined threshold (ΔTALARM) can be achieved using any technique that identifies “odd one out” cases in the signals. In a first preferred embodiment, the controller is configured to compare temperature signals in the following manner: For each temperature signal, calculate the difference between that temperature signal and every other temperature signal; and Each calculated difference is compared with the predetermined threshold (ΔTALARM).

[0015] In a second preferred embodiment, the controller is configured to compare temperature signals in the following manner: Calculate the average value of all temperature signals; For each temperature signal, calculate the difference between that temperature signal and the calculated average value; and Each calculated difference is compared with the predetermined threshold (ΔTALARM).

[0016] In a third preferred embodiment, the controller is configured to compare temperature signals in the following manner: For each temperature signal, calculate the average of all other temperature signals, and then calculate the difference between the current temperature signal and the calculated average; and Each calculated difference is compared with the predetermined threshold (ΔTALARM).

[0017] The predetermined threshold (ΔTALARM) can be factory-set or user-configurable, for example, via a DIP switch provided on the control unit, or configured via suitable software tools. This value may depend on the specific method used to perform the comparison. In a preferred example, the predetermined threshold (ΔTALARM) is any of the following: 4°C, 8°C, 12°C, 16°C, 20°C, 24°C, 28°C, or 32°C. In one embodiment, each of these (or other) options can be selected by the user, for example, by providing a set of three DIP switches.

[0018] Alarm signals can be output in any convenient manner, such as via a siren or light (locally on the controller or on a panel elsewhere), and / or via wired or wireless data connection to another device, such as a central controller. Preferably, the alarm signal includes identification of which thermal sensor triggered the alarm. This allows for the rapid identification and repair of damaged connections.

[0019] Thermal sensor assemblies can be supplied as a single, integral unit, such as a continuous cable with the thermal sensor connected in place. However, in other cases, it is advantageous to supply thermal sensor assemblies in a modular manner, for example, in field-connected configurations. In this case, the cable preferably comprises two or more cable segments detachably connected to each other via connectors, which preferably include keying features such that they are coupled in a single opposing direction. The connectors can take the form of, for example, plug and socket connectors, such as RJ45 plugs and corresponding sockets. Preferably, each cable segment comprises a thermal sensor cable sub-segment and a link cable sub-segment, optionally detachably connected to each other via connectors, the thermal sensor cable sub-segment comprising at least one thermal sensor. If the thermal sensor cable sub-segments and link cable sub-segments are detachable from each other, the thermal sensor assembly can be supplied as a kit comprising a plurality of thermal sensor cable sub-segments and a plurality of link cable sub-segments, one of which is equipped with an end module (optionally including a controller). The various parts can then be assembled to form a complete assembly. Preferably, the connectors will be configured to allow connection in only one direction to ensure correct wiring. Thermal sensor cable sub-segments can be marked to ensure they are connected in the correct order.

[0020] Whether the thermal sensor assembly comprises a single cable or multiple cable segments, the circuitry and thermal sensor are contained within the cable, for example, within an outer sheath. The outer sheath itself may be continuous along the assembly, or it may be formed by multiple connecting portions corresponding to the cable segments.

[0021] A thermal sensor assembly may include any number of thermal sensors, greater than two. In a preferred embodiment, the plurality of thermal sensors includes at least six or at least eight thermal sensors. In a particularly preferred embodiment, the thermal sensor assembly includes exactly six or exactly eight thermal sensors. The more thermal sensors there are, the more wiring is required, and therefore the thicker the cables, which can be disadvantageous.

[0022] The thermal sensors are spaced apart along the length of the cable, preferably at substantially equal intervals. The spacing can be selected based on the typical spacing of joints in a standard busbar conduit system. For example, in a preferred embodiment, the spacing between each thermal sensor can be between 2 and 4 meters, more preferably approximately 3 meters. Therefore, a thermal sensor assembly comprising six thermal sensors spaced 3 meters apart would be able to monitor a 15-meter busbar conduit.

[0023] Any type of thermal sensor can be used in the component, but preferably all thermal sensors are of the same type. Ideally, the thermal sensor is a contact thermal sensor designed to be placed close to the junction to be monitored and to experience a corresponding temperature rise if the junction heats up. In a preferred embodiment, each of the plurality of thermal sensors includes a thermistor, thermocouple, resistance temperature detector (RTD), or semiconductor-based sensor.

[0024] The controller may optionally be configured to perform one or more further routine actions, such as providing backup alarm signals. Therefore, in a preferred embodiment, the controller is also configured to compare each temperature signal to a preset critical temperature threshold (TCRIT) and generate an alarm signal if any temperature signal exceeds the preset critical temperature threshold (TCRIT). In this way, an alarm is generated if any one or more thermal sensors detect an abnormally high temperature (exceeding TCRIT). This can be used to detect excessively high loads erroneously applied to the power distribution system, for example, due to an upstream fault. The value of the predetermined threshold (TCRIT) can be factory-set or user-configurable, for example, via a DIP switch provided on the control unit, or via suitable software tools. In a preferred example, TCRIT can be set to any one of 55°C, 60°C, 65°C, 70°C, 80°C, 85°C, or 90°C. In one embodiment, one of these (or other) options can be user-selectable, for example, by providing a set of three DIP switches.

[0025] In another preferred embodiment, the thermal sensor assembly may further include an ambient temperature sensor (e.g., an additional thermal sensor located away from any connector, preferably close to the controller) configured to output an ambient temperature signal to the controller. The controller is preferably also configured to calculate, for each temperature signal, the difference between that temperature signal and the ambient temperature signal, and compare that difference with a preset critical temperature difference threshold (ΔTCRIT). If the difference is greater than the preset critical temperature difference threshold (ΔTCRIT), an alarm signal is generated. This provides a more accurate method for monitoring abnormally high temperatures because any local fluctuations in ambient temperature are taken into account, thereby reducing false alarms. In a preferred example, the controller may be configured to generate a warning alarm signal if a first value of ΔTCRIT is exceeded, and a critical alarm signal if a second, larger ΔTCRIT value is exceeded. For example, the warning value ΔTCRIT could be 30°C, and the critical value ΔTCRIT could be 40°C, conforming to the NETA standard.

[0026] The thermal sensor assembly can be a standalone unit designed to issue a local alarm, such as via a light or sounder, when an alarm signal is generated. However, in a preferred embodiment, the assembly may also, or alternatively, further include a communication module for outputting temperature signals and / or any alarm signals from the controller to an external device, such as a central controller, for example, in the form of a computer. For example, the communication module may be configured to communicate with the central controller via the MODBUS protocol.

[0027] Each controller will typically require power, therefore the thermal sensor assembly preferably also includes a power module for supplying power to the controller from a local or external power source. If a local power source is used, this may include a battery or solar panel. The power module may include an adapter for converting AC input from an external power source into DC power for the controller. Alternatively, the external power source may be a DC power source.

[0028] A second aspect of the present invention provides a thermal sensor system comprising a plurality of thermal sensor components, each thermal sensor component being configured according to a first aspect of the present invention, wherein each controller (each forming part of an end module) is powered by a common power source. Preferably, the common power source is a DC power source.

[0029] Each controller can be equipped with a separate power adapter and configured to receive power from the mains power supply. However, more preferably, the controllers are divided into two or more groups, each group comprising at least two controllers, each group having an input power connection for receiving power from the common power supply and an output power connection for supplying power to the other group of controllers. This simplifies installation and reduces the number of required parts. More thermal sensor components can be added to the system in a plug-and-play manner.

[0030] In a preferred embodiment, the system further includes a central controller (e.g., a computer or control panel), with each controller configured to communicate with the central controller. The controllers are preferably divided into two or more groups, each group comprising at least two controllers, and each group of controllers is equipped with a data connection for exchanging data with the central controller and / or with another group of controllers. Similarly, this grouping of controllers simplifies installation by reducing the number of connections that need to be established. As mentioned above, communication can be achieved via the MODBUS protocol.

[0031] In a particularly preferred embodiment, input power connections, output power connections, and data connections are provided by RJ45 socket inputs and RJ45 socket outputs at each group of controllers. For example, each group (e.g., two) of controllers can be housed in a respective enclosure that provides a single RJ45 socket input and a single RJ45 socket output for supplying data and power to / from the controller (which can be implemented as a data card). Multiple thermal sensor assemblies can then be connected to the system using standard cables (e.g., CAT5 or other Ethernet cables) for simple power and communication transmission.

[0032] A third embodiment of the invention provides a set of busbar segments for a power distribution system, each busbar segment comprising an elongated housing containing a plurality of conductors for distributing power in use, the conductors extending along the elongated length of the housing between connection points at each end for connection to another busbar segment, and each busbar segment further comprising a thermal sensor assembly segment comprising a cable segment including at least one thermal sensor and a plurality of connectors located at each end of the cable segment, configured such that when the set of busbar segments is connected, the connected cable segments form a cable, the cable including a plurality of at least three thermal sensors arranged along the length of the cable, each of the thermal sensors being spaced apart from the next thermal sensor by a gap, and circuitry located within the cable connecting each of the thermal sensors to one pair of a corresponding plurality of terminal pairs, such that each terminal pair outputs a temperature signal indicating the temperature sensed by the corresponding thermal sensor.

[0033] As described above, the thermal sensor assembly of the first embodiment can be provided in a modular form. In the third embodiment of the invention, the module is combined with a conductor strip segment, allowing the installation of the thermal sensor assembly to be performed simultaneously with the construction of the power distribution system. The cable segment can be located within the conductor strip segment or can be attached externally. Preferably, each cable segment includes a thermal sensor cable sub-segment and a link cable sub-segment, optionally detachably connected to each other via a connector, the thermal sensor cable sub-segment including at least one thermal sensor. For example, a set can be provided as a kit comprising a plurality of conductor strip segments, each conductor strip segment having a link cable sub-segment extending its length, and a corresponding plurality of thermal sensor cable sub-segments. When installing the conductor strip segments, the thermal sensor cable sub-segments can then be used to connect each pair of adjacent link cable sub-segments at each joint location. In this way, all conductor strip segments can be manufactured to the same specifications (including the link cable sub-segments), and only one set of thermal sensor cable sub-segments needs to be configured differently for each joint location (each thermal sensor connects to a different pair of wires in the cable). As before, the thermal sensor cable sub-segments can be marked to ensure they are connected in the correct order. An end module connecting the terminal pairs to the controller can then be provided. The controller is configured to receive temperature signals from each terminal pair and compare the temperature signals to each other to determine if the difference between the temperature sensed by any one thermal sensor and the temperature sensed by the other thermal sensors is greater than a predetermined threshold (ΔTALARM). If so, an alarm signal is generated, as described above.

[0034] A fourth embodiment of the present invention provides a power distribution system comprising one or more conductor segments, each conductor segment including conductors for distributing power in use, and a thermal sensor assembly according to a first embodiment or a thermal sensor system according to a second embodiment, configured such that each thermal sensor is positioned as a connector adjacent to a junction in the power distribution system, preferably a junction between conductor segments or a junction between a conductor segment and a power socket optionally fixed to the conductor segment.

[0035] A fifth embodiment of the present invention provides a method for monitoring fault connections in a power distribution system, the power distribution system including one or more busbar segments, each busbar segment comprising a plurality of conductors for distributing power in use, comprising: providing a plurality of at least three thermal sensors, each thermal sensor being located near a joint in the power distribution system, preferably a joint between busbar segments or a joint between a busbar segment and a power outlet optionally fixed to the busbar segment; monitoring a temperature signal output by each of the plurality of thermal sensors; comparing the temperature signals with each other to determine whether the difference between the temperature sensed by any one of the thermal sensors and the temperature sensed by the other thermal sensors exceeds a predetermined threshold (ΔTALARM), and if so, generating an alarm signal.

[0036] This method offers all the advantages of describing the first-state sample and is preferably implemented using a thermal sensing component based on the first-state sample.

[0037] As described above, the comparison that leads to the generation of the alarm signal can be performed in various different ways. In a first preferred embodiment, comparing the temperature signal includes: For each temperature signal, calculate the difference between that temperature signal and every other temperature signal; and Each calculated difference is compared with the predetermined threshold (ΔTALARM).

[0038] In a second preferred embodiment, the comparison temperature signal includes: Calculate the average value of all temperature signals; For each temperature signal, calculate the difference between that temperature signal and the calculated average value; and Each calculated difference is compared with the predetermined threshold (ΔTALARM).

[0039] In a third preferred embodiment, the temperature signal comparison includes: For each temperature signal, calculate the average of all other temperature signals, and then calculate the difference between the current temperature signal and the calculated average; and Each calculated difference is compared with the predetermined threshold (ΔTALARM).

[0040] The method may also include performing one or more additional functions, such as providing a backup alarm. Preferably, the method further includes comparing each temperature signal with a preset critical temperature threshold (TCRIT), and generating an alarm signal if any temperature signal is greater than the preset critical temperature threshold (TCRIT). The method may also include: providing an ambient temperature sensor; and for each temperature signal, calculating the difference between the temperature signal and the ambient temperature, comparing the difference with a preset critical temperature difference threshold (ΔTCRIT), and generating an alarm signal if the difference is greater than the preset critical temperature difference threshold (ΔTCRIT). Simple Explanation of the Diagram

[0041] Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings, wherein: Figure 1 schematically shows a portion of a disassembled conventional power distribution system; Figure 2 schematically shows a portion of a power distribution system according to an embodiment of the present invention; Figure 3 depicts an embodiment of the thermal sensor assembly according to the present invention, not drawn to scale; Figure 4(a) schematically shows an exemplary circuit that can be provided in the thermal sensor assembly of Figure 3; Figure 4(b) shows an exemplary component of the end module in a plan view, which can be used with the circuit of Figure 4(a); Figures 5(a) to (d) show components of another embodiment of the thermal sensor assembly according to the present invention; Figure 6 schematically shows one of a set of bus bar segments according to an embodiment of the present invention; and Figure 7 schematically shows an embodiment of the thermal sensor system according to the present invention. Implementation

[0042] For the context, Figure 1 schematically shows selected elements of a conventional busbar conduit power distribution system 1. System 1 comprises a plurality of busbar segments 2 (only one is shown), each typically including a metal housing 4 that houses multiple busbar conductors 5 extending along the elongated length of segment 2. Mounting fixtures 3 are provided for assembling the busbar system to a structure such as a building. Busbar segments 2 are typically supplied in standard lengths, such as 3 meters. To distribute power to the desired locations, multiple busbar segments are connected using joint kits 6. Joint kits 6 form an electrical connection between conductors 5 of one segment 2 and conductors 5 of the next segment. As mentioned above, over time, movement of the supporting structure and the busbar segments 2 relative to each other can cause the joints to loosen and thus become damaged. Damaged electrical connections can lead to increased temperature due to increased resistance.

[0043] Figure 2 illustrates a typical busbar conduit layout of a power distribution system 1 according to an embodiment of the present invention. In this example, the system includes multiple conductor segments 2 connected by connector kits 6. Connector kit 6' is a T-joint, allowing another set of conductors to branch off, while connector kit 6" is an elbow joint. A tap 9 is provided at a selected joint for reorienting the system at corners. A tap 9 is provided at a selected joint for connecting to a device (not shown) powered by the system. The power distribution system 1 is provided with at least one thermal sensor assembly 10 (a second thermal sensor assembly 10' is also shown here). The thermal sensor assembly 10 will be described in more detail below. As can be seen in Figure 2, the thermal sensor assembly 10 includes a plurality of thermal sensors 11a, 11b, 11c, which are coupled into a cable 15 and spaced apart along the cable 15. Each thermal sensor 11a, 11b, 11c is placed near one of the joints in the power distribution system. At one end of the cable 15, an end module including a controller 19 is provided, which receives temperature signals from the thermal sensors 11a, 11b, 11c and determines whether an alarm should be generated. Each controller 19 may be equipped with an output module for indicating an alarm or transmitting an alarm to an external device, such as a central controller.

[0044] It should be noted that although Figure 2 depicts the thermal sensor assemblies 10, 10' as located outside the bus conduit system, the thermal sensor assemblies can alternatively be located inside the bus conduit housing, as shown below with reference to Figure 6. This may be suitable, for example, when the thermal sensing system is installed concurrently with the power distribution system. Conversely, external mounting allows the thermal sensing system to be retrofitted to an existing installation.

[0045] Figure 3 shows an embodiment of the thermal sensor assembly 10 in more detail (not to scale). The thermal sensor assembly 10 can be implemented as a low-cost sensor loom, which can be easily attached to the housing of the busbar conduit 2 (or can be installed inside) via cable tie or clamp assembly. The assembly 10 is presented as a single (multi-core) cable 15 instead of multiple separate cables, which simplifies installation.

[0046] The thermal sensor assembly 10 includes a plurality of individual thermal sensors 11, such as thermistors or thermocouples (or other thermal sensor technologies), spaced apart along the cable 15. Contact thermal sensors, such as these examples, are generally preferred. In this embodiment, the thermal sensor assembly 10 includes six thermal sensors 11a to 11f, each spaced apart from the other by approximately 3 meters. In practice, these spacings are chosen to correspond to the joints 6 of the cable tray 2 in the power distribution system. Therefore, the spacing distance can be varied to suit the system in question. Typically, the spacing will be in the range of 2 to 4 meters. Preferably, the spacing between each thermal sensor on the cable is the same, but this is not required. The exemplary thermal sensor assembly 10 shown has six sensors, each spaced 3 meters apart, which will allow us to monitor each sensor bundle 15 meters of busbar conduit. The cable 15 may be labeled with tags 12 for quick identification of each thermal sensor. Cable 15 can be modularized at each sensor location to house the thermal sensor 11 around the main cable, such that the thermal sensor and cable circuitry are contained within the outer cable sheath. In the example, the modularized areas can have a length L1 of approximately 25 mm and a diameter of approximately 7 mm, while the sections of cable 15 between them can have a length L2 of approximately 3 meters and a diameter of approximately 6 mm. Element 14 is an optional ambient temperature sensor.

[0047] Cable 15 includes circuitry connecting each thermal sensor 11 to an end module 18, which includes a plurality of terminals, denoted herein as pins 18b. In this example, the end module includes a connector 18a with pins 18b for corresponding connection coupling with a controller 19 (e.g., a plug and socket connector). However, the connection from the terminals to the controller 19 can be made in any convenient manner, including hard-wiring the terminals to the controller 19 via a terminal strip. The circuitry connects each thermal sensor 11 to a pair of terminals 18b (forming a “terminal pair”) such that a corresponding temperature signal from the thermal sensor is output through this pair. The terminals are connected to the controller 19, which is typically implemented on a local datacard, and receives the temperature signal from each thermal sensor 11. The controller 19 is configured to perform comparisons between the temperature signals and determine whether any one of the temperature signals differs from the other temperature signal by more than a predetermined amount (ΔTALARM), which will be described in more detail below. If so, it indicates that the corresponding connector where the thermal sensor that returns the high temperature signal is located has malfunctioned, and the controller 19 generates an alarm signal accordingly.

[0048] Figure 4(a) is a schematic diagram showing a preferred circuit layout of the thermal sensor assembly of Figure 3. It will be seen that the cable provides six measuring lines 16a to 16f, one for each sensor, and a common return line 17 connected to ground. Each thermal sensor 11a to 11f is connected to its respective measuring line 16a to 16f and return line 17. This design allows the use of a seven-core cable (one core for each line) as the basis for assembly 10, resulting in a small cable diameter. Each measuring line 16a to 16f and return line 17 are connected at one end of the cable to one of the terminal pins 18b in the end module 18. In a preferred example, the end module 18 includes a standard Molex type 12-pole connector (shown as element 18a in the plan view of Figure 4(b)), in which case the return line 17 is connected to common ground connection pins 1 to 6.

[0049] It should be understood that the same principle can be extended to provide different numbers of thermal sensors 11. For example, a 16-pole connector 18a and a nine-core cable can be used to provide eight thermal sensors 11 along the cable (if spaced 3 meters apart), which would allow monitoring of 21 meters and 8 connectors for each component 10.

[0050] The signal processing capability of controller 19 can be implemented in hardware, firmware, or software, or any combination thereof. Preferably, signal processing is performed locally by controller 19, for example on a data card provided within end module 18, but in other cases, the controller can be remote, providing suitable wired or wireless connectivity to enable controller 19 to receive signals from terminal 18b. For example, each end module 18 can instead be equipped with a communication device that simply transmits signals to the remote controller 19 without performing local calculations (other than any analog-to-digital conversion or other processing that may require data transmission).

[0051] In most cases, the length of the busbar conduit should have the same load passing through the busbar, so the load at each joint is the same. Under normal conditions (within one or two degrees of temperature), all joints along this should be at substantially the same temperature. Therefore, the controller 19 is configured to look for “special” conditions along the monitored joints. This routine can be performed by many alternative processes. In a first preferred embodiment, the controller 19 compares each temperature signal with every other temperature signal and calculates whether the difference between the temperatures is greater than a predetermined threshold ΔTALARM. For example, in the case of monitoring the temperatures of six joints A to F, the controller can make the following comparison (where “Ti” is the temperature of joint i, derived from the temperature signal output by the thermal sensor located at the i-th position): • Is TA-ΔTALARM>TB? • Is TA-ΔTALARM>TC • Is TA-ΔTALARM>TD? • Is TA-ΔTALARM>TE? • Is TA-ΔTALARM>TF? • Is TB-ΔTALARM>TA • Is TB-ΔTALARM>TC • Is TB-ΔTALARM>TD • Is TB-ΔTALARM>TE • Is TB-ΔTALARM>TF? • Is TC-ΔTALARM>TA ...and so on for all connector pairs.

[0052] Essentially, this routine check determines whether the temperature of any connector below the alarm level (ΔTALARM) is higher than the temperature of any other connector. If any one or more comparisons return a positive result, controller 19 generates an alarm signal. This can be output locally (e.g., via a sounder, light, and / or display) and / or transmitted to an external device, such as a central controller or control panel. Preferably, the alarm includes information about which thermal sensor triggered the alarm so that the corresponding connector can be quickly identified.

[0053] It should be understood that other ways of performing the comparison exist, such as calculating whether Ti - Tj > ΔTALARM (where Ti and Tj are the temperatures of joint i and joint j, respectively, derived from the temperature signals output by thermal sensors located at joint i and joint j). There is no substantial difference between these methods.

[0054] In an alternative embodiment, controller 19 may be configured to perform the determination of whether an "odd one out" condition exists in a different manner. For example, the computational cost of comparing each temperature signal to an average temperature value, rather than comparing each of the other temperature signals individually, may be lower. Thus, in a preferred embodiment, with N thermal sensors, controller 19 may be configured to compare the temperature signals by: calculating the average value (TAV.N) of all temperature signals; for each temperature signal (T1...N), calculating the difference between that temperature signal and the calculated average value; and comparing each calculated difference value with a predetermined threshold (ΔTALARM). Alternatively, controller may be configured to compare the temperature signals by: for each temperature signal (T1...N), calculating the average value of all other temperature signals (TAV.N-1), then calculating the difference between the temperature signal and the calculated average value; and comparing each calculated difference value with a predetermined threshold (ΔTALARM). In both cases, an alarm signal is generated if any calculated difference value is found to be greater than ΔTALARM.

[0055] The value of ΔTALARM can be factory set or user-configurable, for example, via a set of DIP switches provided on controller 19. In a preferred example, the value of ΔTALARM can be any of the following: 4°C, 8°C, 12°C, 16°C, 20°C, 24°C, 28°C, or 32°C. A set of eight such values ​​can be implemented in a user-selectable manner using a set of three DIP switches, achieving an arrangement from 0,0,0 to 1,1,1. Of course, alternative ΔTALARM values ​​can be provided depending on the installation configuration. Alternatively, a software tool can be provided to set the ΔTALARM value instead of using DIP switches.

[0056] Optionally, controller 19 can be configured to run one or more additional routines that can provide backup alarm signals. For example, such routines might be able to detect overall system failures or erroneously applied high loads to the power distribution system. This situation could cause multiple connections (e.g., all connections) to overheat, which might not necessarily be detected by the "special case" mentioned above.

[0057] In one embodiment, controller 19 can therefore be further configured to operate a "HIGH" function, which compares each temperature signal with a preset critical temperature threshold (TCRIT) and generates an alarm signal if any temperature signal is greater than the preset critical temperature threshold (TCRIT). Similarly, the value of TCRIT can be factory-set or user-configurable, for example, via a DIP switch or software tool. Alternatively or additionally, thermal sensor assembly 10 may be provided with an ambient thermal sensor 14 (FIG. 3), and controller 19 can be configured to operate a "DELTA HIGH" function, in which the temperature signal is compared with the local ambient temperature, and an alarm is triggered if the difference is greater than a preset critical temperature difference threshold (ΔTCRIT). Again, the value of ΔTCRIT can be factory-set or user-configurable, for example, via a DIP switch or software tool. For this general case, controller 19 can be configured to calculate the difference between the temperature measured by each thermal sensor and the ambient temperature TAMB, and check if the difference is greater than ΔTCRIT. For example, in assembly 10 which has six thermal sensors at joints A through F, the following comparison can be performed: • Is TA-TAMB > ΔTCRIT? • Is TB-TAMB > ΔTCRIT? • Is TC-TAMB > ΔTCRIT? • Is TD-TAMB > ΔTCRIT? • Is TE-TAMB > ΔTCRIT? • Is TF-TAMB > ΔTCRIT? An alarm signal is generated if any comparison yields a positive result.

[0058] In the above embodiments, the thermal sensor assembly 10 is provided as a single unit formed of a continuous cable 15, with the thermal sensor 11 connected to the continuous cable 15 at an appropriate location. However, in other embodiments, it may be preferable to provide the thermal sensor assembly 10 in a modular form (i.e., as a kit of parts) that can be connected together to form an assembly. Figures 5(a) to (d) show such embodiments. Here, the kit includes a plurality of thermal sensor cable sub-segments 21 (one of which is shown in Figure 5(a)) and a plurality of link cable sub-segments 22, 23 (two examples of which are shown in Figures 5(b) and 5(c)).

[0059] The thermal sensor cable sub-segment 21 includes a thermal sensor 11 connected to a cable portion 15 on either side, with a connector 29 at each end. The cable 15 is a multi-core cable (e.g., a seven-core cable) as previously described, and the thermal sensor 11 is connected to one of the measuring lines and a return line passing through the cable 15. The length of the thermal sensor cable sub-segment 21 may be, for example, approximately 150 mm. Preferably, each is equipped with a label 12 to ensure they are connected in the correct order. The connector 29 is a multi-pin connector, preferably a plug and socket type, which allows the thermal sensor cable sub-segment 21 to be connected at one or both ends to link cable sub-segments 22, 23.

[0060] Each of the connecting cable sub-segments 22 and 23 essentially includes a pre-fabricated mating cable carrying the necessary number of wires, with a corresponding connector 29 at at least one end for connection to the thermal sensor cable sub-segment 21. For example, in this example, cable 15 is again a seven-core cable. Connector 29 may be a multi-pin plug / receptacle connector, and possible configurations are shown in Figure 5(d), with each pin labeled with the cable it connects to. The pin / receptacle configuration on each connector 29 is identical. Preferably, connector 29 includes a keying feature 29a to ensure they mate only in a single, unique orientation to prevent the lines from crossing.

[0061] The link cable sub-segment 23 shown in Figure 5(c) is configured to be mounted at the first end of the thermal sensor assembly, and thus an end module 18 is provided at one end thereof. The controller 19 may also be provided as a connector 18b connected to the end module 18, or the connection may be made in the field.

[0062] An alternative method for connecting between sensor modules is to use RJ45 sockets as connectors 29 at each end of the thermal sensor cable sub-segment 21. This allows for greater flexibility in branch length and busbar conduit length, as “off-the-shelf” CAT5 / 6 patch cables can be used between modules 21 to overcome any boundaries with different conduit lengths.

[0063] Once these sub-segments 21, 22, and 23 are connected, the resulting thermal sensor assembly has essentially the same form as described with respect to Figure 3 and the same circuitry as shown in Figure 4. It should be understood that the order in which the thermal sensor cable sub-segments 21 are connected to the link cable sub-segments is important—they are not interchangeable because in each, the thermal sensor 11 is connected to a different measuring line 16. The measuring line connecting the thermal sensor in each sub-segment effectively terminates in that sub-segment, so the corresponding core wire in the downstream cable segment will not carry any signal. Preferably, the thermal sensors 11 are connected in a predetermined order such that each thermal sensor 11 is bridged across a pair of preselected terminals 18b, and the controller 19 is programmed to associate the signal bridging this pair of terminals with the corresponding thermal sensor 11 (thus the connector is in this position). In this case, if the thermal sensors 11 are connected in a different order, the terminal pair outputting the corresponding temperature signal will not be the intended terminal pair, and therefore an alarm signal may indicate a faulty connector.

[0064] Of course, ideally, the thermal sensor cable sub-segments 21 can be connected in any order (so each sub-segment is connected to any terminal pair). A configuration process can then be performed to identify which thermal sensor corresponds to which temperature signal detected across the terminal pair. This can be done, for example, by sequentially providing a heat source near each temperature sensor and identifying which temperature signal increases. In this way, a correlation can be established between each temperature signal and each thermal sensor (and therefore, the connector location).

[0065] The modular system described above is well-suited for simultaneous installation with the power distribution system 1 itself. For example, each busbar segment 2 can be provided pre-assembled with a link cable sub-segment 22 extending along its length, either internally or externally. This is schematically depicted in Figure 6. Each busbar segment 2 can also carry a thermal sensor cable sub-segment 21 connected to one end of the link cable sub-segment 22, or this can be provided separately. When the power distribution system is installed, and when the busbar conductors 5 are connected at each connector kit 6, the link cable sub-segments 22 in each busbar segment 2 will also be interconnected via sensor modules 21, where thermal sensors are appropriately positioned at each connector. At one end, link cable sub-segments 23 will be assembled with end modules 18 and controllers 19 to complete the thermal sensor assembly 10.

[0066] A typical power distribution system 1 will include a large number of joints that need to be monitored. While in some cases a large number of thermal sensors can be equipped on a single thermal sensor assembly, in practice, the number of lines and therefore the number of cores required will quickly lead to the need for cables 15 of excessive diameter to receive all the temperature signals. Therefore, it is preferable to use a thermal sensor system 30 comprising a plurality of thermal sensor assemblies 10 to monitor joints, each thermal sensor assembly 10 as described above.

[0067] In such a thermal sensor system 30, each controller 19 requires power and communication. A simple way to achieve this is to place a separate power adapter (e.g., a 24V DC power adapter) in each housing that houses one of the controllers 19, and to install data communication and main power separately for each thermal sensor assembly 10.

[0068] However, a simpler and more economical installation method can also be achieved as follows. As shown in Figure 7, the thermal sensor system 30 includes a plurality of thermal sensor assemblies 10, here 12 such assemblies. Each controller 19 receives power from a common power supply 31 (e.g., a 24V DC power supply). This can be supplied individually to each controller. However, more preferably, the controllers 19 are grouped into groups of two or more controllers, each group being assembled into a small enclosed housing 32, of which six are provided in the example of Figure 7 (enclosed housings 32a to 32f). In this case, each group consists of two controllers 19. Each pair of assemblies 10 has its own cable 15 and an associated thermal sensor 11, which are arranged to monitor connectors in different (preferably opposite) directions. Thus, with each thermal sensor assembly including six thermal sensors spaced 3 meters apart, this allows monitoring of a 33-meter busbar conduit from each enclosed housing 32. In the arrangement shown, each line of the three enclosed housings 32a, 32b, 32c on one side and 32d, 32e, and 32f on the other side can thus monitor a busbar conduit up to 105 meters long.

[0069] Preferably, each enclosure 32 is provided with power input and power output connections, allowing the enclosure 32 to be connected in series to a common power supply 31, as shown in Figure 7. For example, each controller 19 can typically operate from 12V dc to 24V dc, so each enclosure 32 can be fitted with a single RJ45 socket input and a single RJ45 socket output. Internally, these will be connected to each of the two controllers 19 within the enclosure 32. Power and data can then be transmitted to or from each enclosure 32 along the connecting cable 33 (e.g., CAT5 or better Ethernet cable), ensuring optimization and simplified installation. Installation can be performed, for example, via a "plug and play" method, with additional components 10 added to the system 30 as needed. Thus, an easy-to-install kit can be created that includes prefabricated enclosures 32 connected to CAT5 or better cables 33. Controllers 19 can be configured to communicate with a central controller (which can be integrated with the power supply unit 31), for example, via the MODBUS protocol.

[0070] Typically, each controller 19 consumes approximately 30mA of current, but if we assume a worst-case scenario of 50mA, then using a CAT5 cable with a cross-sectional area of ​​0.2mm² and a resistance of 10.5Ω per 100 meters will result in: V = IR = 100mA * 10.5Ω = 1.05V DC voltage drop at a distance of 100 meters. V = IR = 100mA * 7Ω = 0.7V DC voltage drop at a distance of 66 meters. If we increase the load to 400mA to the furthest unit V = IR = 400mA * 10.5Ω = 4.2V DC voltage drop at a distance of 100 meters. V = IR = 400mA * 7Ω = 2.8V DC voltage drop at a distance of 66 meters.

[0071] Therefore, we can see from this that if the 24V DC power is supplied by the common power supply 31, our worst-case scenario is that we would see a drop to approximately 19V DC at the furthest enclosed housing 32, which is well within the capability of the controller 19. This would allow a small 24VDC 2.5A power supply 31 located in a central position to connect to 12 controllers 19 (six enclosed housings 32) and monitor a 200-meter bus conduit containing 72 connectors, as shown in Figure 7.

[0072] 1: Busbar conduit power distribution system, power distribution system, system 2: Cable strip segments, segments, cable trays 3: Install the clamps 4: Outer shell 5: Conductor bar, conductor 6: Connector kit, connector 6': Connector Kit 6": Connector Kit 9: Taper 10: Thermal sensor components, components 10': Second thermal sensor assembly, thermal sensor assembly 11: Thermal Sensor 11a: Thermal sensor 11b: Thermal sensor 11c: Thermal sensor 11d: Thermal sensor 11e: Thermal sensor 11f: Thermal sensor 12: Tags 14: Ambient temperature sensor, ambient heat sensor 15: Cable 16: Measuring line 16a: Measuring line 16b: Measuring line 16c: Measuring line 16d: Measuring line 16e: Measuring line 16f: Measuring line 17: Common return line, return line 18: End Module 18a: Connector 18b: Pins, terminals, terminal pins, connectors 19: Controller 21: Thermal sensor cable sub-segment, sub-segment, module, sensor module 22: Connecting cable sub-sections, sub-sections 23: Connecting cable sub-sections, sub-sections 29: Connector 29a: Keying features 30: Thermal sensing system, system 31: Common power supply, power supply unit, power supply 32: Enclosed shell 32a: Enclosed shell 32b: Enclosed housing 32c: Enclosed housing 32d: Enclosed shell 32e: Enclosed housing 32f: Enclosed shell 33: Connecting cables, electrical cables L1: Length L2: Length

Claims

1. A thermal sensor assembly for a power distribution system, comprising: A cable comprising a plurality of at least three thermal sensors arranged along the length of the cable, each of the thermal sensors being spaced apart from the next thermal sensor by a gap; an end module located at a first end of the cable, the end module having a corresponding plurality of terminal pairs, each terminal pair being dedicated to one of the thermal sensors; A circuit, located within the cable, connects each of the thermal sensors to a corresponding pair of the terminal pairs, such that each terminal pair outputs a temperature signal indicating the temperature sensed by the corresponding thermal sensor; and a controller configured to receive the temperature signal from each terminal pair and compare the temperature signals with each other to determine whether the temperature sensed by any one of the thermal sensors differs from the temperature sensed by the other thermal sensors by more than a predetermined threshold (ΔTALARM), and if so, generate an alarm signal.

2. The thermal sensor assembly as claimed in claim 1, wherein, The circuit includes a plurality of corresponding measurement lines and a common return line, each of the measurement lines connecting one of the thermal sensors to the first terminal of a corresponding terminal pair in the end module, and the common return line connecting each of the thermal sensors to the second terminal of a corresponding terminal pair in the end module.

3. The thermal sensor assembly as described in claim 1 or 2, wherein, The controller is configured to compare the temperature signal by: for each temperature signal, calculating the difference between the temperature signal and each other temperature signal; and comparing each calculated difference with a predetermined threshold (ΔTALARM).

4. The thermal sensor assembly as claimed in claim 1 or 2, wherein, The controller is configured to compare the temperature signal by: calculating the average of all such temperature signals; for each temperature signal, calculating the difference between the temperature signal and the calculated average; and comparing each calculated difference with a predetermined threshold (ΔTALARM).

5. The thermal sensor assembly as claimed in claim 1 or 2, wherein, The controller is configured to compare the temperature signal by: for each temperature signal, calculating the average of all other temperature signals, then calculating the difference between the temperature signal and the calculated average; and comparing each calculated difference with a predetermined threshold (ΔTALARM).

6. The thermal sensor assembly as claimed in claim 1 or 2, wherein, The alarm signal includes identification of which thermal sensor triggered the alarm.

7. The thermal sensor assembly as claimed in claim 1 or 2, wherein, The cable comprises two or more cable segments that are detachably connected to each other via connectors, which preferably include keying features that allow them to couple in a single relative direction.

8. The thermal sensor assembly as claimed in claim 7, wherein, Each of the cable segments includes a thermal sensor cable sub-segment and a link cable sub-segment, which are optionally detachably connected to each other via a connector, and the thermal sensor cable sub-segment includes at least one of the thermal sensors.

9. The thermal sensor assembly as claimed in claim 1 or 2, wherein, The plurality of thermal sensors includes at least six thermal sensors.

10. The thermal sensor assembly as claimed in claim 1 or 2, wherein, The spacing between these thermal sensors is between 2 meters and 4 meters, preferably about 3 meters.

11. The thermal sensor assembly as claimed in claim 1 or 2, wherein, Each of the plurality of thermal sensors includes a thermistor, thermocouple, resistance temperature detector (RTD), or semiconductor-based sensor.

12. The thermal sensor assembly as claimed in claim 1 or 2, wherein, The controller is further configured to compare each of the temperature signals with a preset critical temperature threshold (TCRIT), and to generate an alarm signal if any of the temperature signals exceeds the preset critical temperature threshold (TCRIT).

13. The thermal sensor assembly as claimed in claim 1 or 2, further comprising an ambient temperature sensor, and wherein, The controller is further configured to calculate the difference between the temperature signal and the ambient temperature for each temperature signal, compare the difference with a preset critical temperature difference threshold (ΔTCRIT), and generate an alarm signal if the difference is greater than the preset critical temperature difference threshold (ΔTCRIT).

14. The thermal sensor assembly as claimed in claim 1 or 2, further comprising a communication module for outputting the temperature signal and / or any alarm signal from the controller to an external device.

15. The thermal sensor assembly as claimed in claim 1 or 2, further comprising a power module for supplying power to the controller from a local or external power source.

16. A thermal sensing system comprising a plurality of thermal sensing components as described in any one of claims 1 to 15, wherein, Each of the corresponding controllers is powered by a common power source.

17. The thermal sensor system as claimed in claim 16, wherein, The controllers are divided into two or more groups, each group including at least two of the controllers, each group of controllers being provided with an input power connection for receiving power from the common power source and an output power connection for supplying power to another group of controllers.

18. The thermal sensor system as claimed in claim 16, wherein, The system further includes a central controller, with corresponding controllers configured to communicate with the central controller. Preferably, the controllers are divided into two or more groups, each group including at least two of the controllers, and each group of controllers is provided with a data connection for exchanging data with the central controller and / or with another group of controllers.

19. The thermal sensor system as claimed in claim 17, wherein, The input power connection, output power connection, and data connection are provided by the RJ45 socket input and RJ45 socket output of each controller group.

20. A parts kit, wherein, When the components are connected together, they form a thermal sensor assembly as described in claim 8, the assembly comprising: a plurality of thermal sensor cable sub-segments and a plurality of link cable sub-segments, the thermal sensor cable sub-segments and the link cable sub-segments being detachably connected, and one of the link cable sub-segments being equipped with an end module.

21. A set of busbar segments for a power distribution system, each busbar segment comprising an elongated housing containing a plurality of conductors for distributing power in use, the conductors extending along the elongated length of the housing between connection points at each end for connection to another busbar segment, and each busbar segment further comprising a thermal sensor assembly segment comprising a cable segment including at least one thermal sensor and a plurality of connectors located at each end of the cable segment, configured such that when the set of busbar segments is connected, the connected cable segments form a cable, the cable including a plurality of at least three thermal sensors arranged along the length of the cable, each of the thermal sensors being spaced apart from the next thermal sensor by a gap, and circuitry located within the cable connecting each of the thermal sensors to one of a corresponding plurality of terminal pairs, such that each terminal pair outputs a temperature signal indicating the temperature sensed by the corresponding thermal sensor.

22. A set of busbar segments for a power distribution system as described in claim 21, wherein, Each of the cable segments includes a thermal sensor cable sub-segment and a link cable sub-segment, which are optionally detachably connected to each other via a connector, and the thermal sensor cable sub-segment includes at least one of the thermal sensors.

23. A power distribution system comprising one or more conductor segments including conductors for distributing power in use, and a thermal sensor assembly as described in any one of claims 1 to 15 or a thermal sensor system as described in any one of claims 16 to 19, arranged such that each thermal sensor is located near a joint in the power distribution system, preferably a joint between the conductor segments or a joint between a conductor segment and a power outlet optionally fixed to the conductor segment.

24. A method for monitoring fault connections in a power distribution system, the power distribution system comprising one or more busbar segments, the busbar segments including a plurality of conductors for distributing power in use, comprising: Provide a plurality of at least three thermal sensors, each of which is located near a connector in the power distribution system, preferably a connector between segments of the conductor strip or a connector between a conductor strip segment and a power socket optionally fixed to the conductor strip segment; monitor the temperature signal output by each of the plurality of thermal sensors; compare the temperature signals with each other to determine whether the difference between the temperature sensed by any one of the thermal sensors and the temperature sensed by the other thermal sensors exceeds a predetermined threshold (ΔTALARM), and if so, generate an alarm signal.

25. The method as described in claim 24, wherein, The comparison of these temperatures includes: for each temperature signal, calculating the difference between the temperature signal and each other temperature signal; and comparing each calculated difference with the predetermined threshold (ΔTALARM).

26. The method as described in claim 24, wherein, The comparison of these temperatures includes: calculating the average value of all the temperature signals; for each temperature signal, calculating the difference between the temperature signal and the calculated average value; and comparing each calculated difference value with the predetermined threshold (ΔTALARM).

27. The method as described in claim 24, wherein, The comparison of the temperatures includes: for each temperature signal, calculating the average of all other temperature signals, then calculating the difference between the temperature signal and the calculated average; and comparing each calculated difference with the predetermined threshold (ΔTALARM).

28. The method of any one of claims 23 to 27, further comprising: Each temperature signal is compared with a preset critical temperature threshold (TCRIT), and an alarm signal is generated if any temperature signal exceeds the preset critical temperature threshold (TCRIT).

29. The method of any one of claims 24 to 27, further comprising: Provides an ambient temperature sensor; For each temperature signal, the difference between the temperature signal and the ambient temperature is calculated, and the difference is compared with a preset critical temperature difference threshold (△TCRIT). If the difference is greater than the preset critical temperature difference threshold (△TCRIT), an alarm signal is generated.

Images