Burst-proof system for capacitors and capacitor device

Abstract

The burst-proof system (1) for capacitors comprises: - at least one strain sensing assembly (9) associated with at least one capacitor device (2) and adapted to sense the strain of the capacitor device (2); and at least one electronic control device (10) operationally connected to the strain sensing assembly (9) and operationally configured to receive from the latter at least one first data item, related to the strain of the capacitor device (2), and to process at least one second data item, related to the first data item and indicative of the risk of potential burst of the capacitor device (2).

Description

[0001] BURST-PROOF SYSTEM FOR CAPACITORS AND CAPACITOR DEVICE

[0002] Technical Field

[0003] The present invention relates to a burst-proof system for capacitors and a capacitor device.

[0004] Background Art

[0005] With particular reference to the field of electronics, the use is well known of particular electronic components, known as capacitors, which have the ability to store electrostatic energy associated with an electrostatic field.

[0006] The capacitors of known type comprise two conducting bodies, made of an electrically conductive material and called armatures, and an insulating body, made of an electrically insulating material, positioned between the conducting bodies and called a dielectric.

[0007] In addition, the capacitors of known type comprise an outer containment body preferably made of aluminum and inside of which the armatures and the dielectric are arranged.

[0008] Preferably, the outer containment body has a substantially cylindrical conformation.

[0009] Capacitor armatures are connectable to an external electrical source through electrical connecting wires that protrude from the top wall of the outer containment body.

[0010] Again, the capacitors of known type can be associated with a fixed structure through a fastening tang that protrudes from the bottom wall of the outer containment body.

[0011] Generally, the dielectric of the capacitors consists of a polypropylene film winding which is externally metallized in order to make the armatures of the capacitor.

[0012] Preferably, metallization of the propylene film is made by depositing a very thin layer of Zinc and Aluminum thereon.

[0013] Sometimes, during the use of capacitors of known type, it may happen that the layer of polypropylene film is perforated at a point that becomes electrically inert and constitutes a discontinuity in the flow of the electric current.

[0014] In this situation, the remaining portions of the polypropylene film ensure the passage of the electric current along the armatures.

[0015] This condition is known as “regeneration of the metallized film” and does not constitute a capacitor failure event but is a condition of normal operation of the latter.

[0016] On the other hand, in the case where the polypropylene film loses its ability to regenerate and the perforation affects an increasing number of layers of polypropylene film, a short circuit condition within the capacitor may result, which can lead to a failure of the latter.

[0017] During short circuiting of a capacitor, it is possible to identify a first phase characterized by a high-impedance short circuit during which polypropylene extrusions are formed that may be involved in a combustion process, resulting in the formation of combustion gases within the outer containment body.

[0018] During the first phase, which generally lasts a few fractions of a second or, at most, a few minutes, the capacitor is still able to withstand the applied voltage, although its functionality is impaired.

[0019] It is possible, as well, to identify a second phase during the short circuit in which there is the formation of a short circuit arc within the capacitor.

[0020] This condition is generated by the progressive combustion of polypropylene and generally leads to the formation of large amounts of combustion gas within the outer containment body, which leads to an increase in pressure therein.

[0021] This increase in pressure causes the walls of the outer containment body to deform and sometimes the outer containment body itself may burst.

[0022] It is easy to appreciate how the burst of the outer containment body makes the capacitor unusable and needs the replacement thereof, resulting in increased costs.

[0023] Added to this is the fact that the burst of a capacitor can lead to damage to other electrical components connected to the deflagrated capacitor and / or to objects and / or people in the proximity of that capacitor.

[0024] To at least partly obviate the aforementioned unpleasant drawbacks, the use is known of burst-proof systems for capacitors which are configured to detect a possible capacitor burst in a timely manner in order to block the passage of current on the armatures prior to deflagration.

[0025] A first type of burst-proof systems of known type involves interrupting the passage of electric current on the armatures by disconnecting the latter from the electrical connecting wires.

[0026] Specifically, as a result of the strain of the outer containment body, the top wall moves away from the armatures causing disconnection of the electrical wires connected to the armatures themselves.

[0027] This can interrupt the passage of the electric current on the armatures, blocking the combustion of the polypropylene film and the consequent production of combustion gases.

[0028] The burst-proof systems of the first type do, however, have some drawbacks that are mainly related to the fact that they often do not intervene in a timely manner to prevent the deflagration of the capacitors or, at least, not to impair their functionality irreparably.

[0029] In other words, in some cases, the burning of the polypropylene film occurs so quickly that the outer containment body bursts before the connecting wires detach from the armatures.

[0030] In other cases, the containment body deforms more slowly, thus allowing the connecting wires to detach from the armatures, but this is unlikely to happen before the functionality of the capacitor is irreparably jeopardized.

[0031] A second type of burst-proof systems of known type involves the use of a pressure sensor adapted to detect the pressure value within the outer containment body and adapted to communicate this data item to an outer management and control unit. Such an outer management and control unit compares the detected pressure value with a standard pressure value related to a limit state of strain of the outer containment body which identifies a possible deflagration condition.

[0032] As soon as the management and control unit detects that this standard pressure value has been exceeded, it intervenes on the external electrical source in order to block the passage of the electric current between the latter and the armatures of the capacitor.

[0033] The burst-proof systems for capacitors of the second type do, however, have some critical issues that are similar to the drawbacks suffered by the burst-proof systems of the first type.

[0034] In this regard, it is worth noting that the burst-proof systems of the second type do not always succeed in intervening in a timely manner in order to prevent the burst of the capacitor.

[0035] In particular, the pressure within the outer containment body increases so rapidly that it is not detected in a timely manner by the pressure sensor to take timely action on the passage of current on the armatures.

[0036] Description of the Invention

[0037] The main aim of the present invention is to devise a burst-proof system for capacitors and a capacitor device which allows the timely detection of a possible explosion of the outer containment body of a capacitor.

[0038] Another object of the present invention is to devise a burst-proof system for capacitors and a capacitor device which allows preserving as much as possible the functionality of the capacitor if it is affected by a condition of short circuit within it.

[0039] A further object of the present invention is to devise a burst-proof system for capacitors and a capacitor device which allows the aforementioned drawbacks of the prior art to be overcome within the framework of a simple, rational, easy and effective to use, as well as affordable solution.

[0040] The aforementioned objects are achieved by this burst-proof system having the characteristics of claim 1.

[0041] The aforementioned objects are also achieved by this capacitor device having the characteristics of claim 17.

[0042] Brief Description of the Drawings

[0043] Other characteristics and advantages of the present invention will become more apparent from the description of some preferred, but not exclusive, embodiments of a burst-proof system for capacitors and a capacitor device, illustrated by way of an indicative, yet non-limiting example in the accompanying tables of drawings in which:

[0044] Figures 1, 2, and 3 are schematic views, from different angles, of a burst-proof system for capacitors according to the invention, associated with a capacitor device and made according to a first embodiment;

[0045] Figure 4 is a schematic view of a burst-proof system for capacitors according to the invention, associated with a capacitor device and made according to a second embodiment;

[0046] Figure 5 is a schematic view of some components of the burst-proof system in Figure 1 and Figure 4;

[0047] Figure 6 is a schematic view of the burst-proof system in Figure 1 and in Figure 4 associated with a plurality of capacitor devices;

[0048] Figure 7 is an axonometric view of a capacitor device according to the invention. With particular reference to these figures, reference numeral 1 globally denotes a burst-proof system for capacitors.

[0049] Within the scope of this disclosure, it has been assumed that the burst-proof system 1 is used to promptly detect a possible deflagration of a capacitor device 2 connected to a power supply unit.

[0050] Embodiments of the Invention

[0051] With special reference to the figures, the capacitor device 2 comprises: at least one outer containment body 3; at least two conductive elements, made of electrically conductive material, arranged internally to the outer containment body 3 and electrically connected to at least one power supply unit; at least one insulating element made of electrically insulating material, positioned between the conductive elements and arranged internally to the outer containment body 3.

[0052] The capacitor device 2 also comprises two electrical connection elements 4 associated with the conductive elements, which can be connected to the power supply unit and adapted to transfer the electric current from the power supply unit to the conductive elements.

[0053] Again, the capacitor device 2 comprises at least one fastening tang 5 adapted to allow the coupling of the capacitor device 2 to a supporting structure.

[0054] With particular reference to the preferred embodiment shown in the figures, the outer containment body 3 has a substantially cylindrical conformation and is provided with a top wall 6, with a lateral wall 7 and with a bottom wall 8.

[0055] The electrical connection elements 4 are associated with the top wall 6 and protrude therefrom.

[0056] The fastening tang 5 is associated with the bottom wall 8 and protrudes from the latter.

[0057] The conductive elements and the insulating element are not shown in the figures for pure descriptive’s sake but are of the type known to the engineer in the field. Under some particular conditions of use, anomalies may be generated during the transmission of electrical energy from the power supply unit towards the conductive elements which may generate a short circuit condition.

[0058] During a short circuit, a combustive process involving the conductive elements and / or the insulating element may be generated, leading to the formation of combustion gases inside the outer containment body 3.

[0059] The outer containment body 3 is insulated from the outside which prevents the combustion gases from escaping from the outer containment body 3 itself.

[0060] Under such conditions, there is an increase in pressure within the outer containment body 3 which gradually deforms until it bursts.

[0061] According to the invention, the burst-proof system 1 comprises: at least one strain sensing assembly 9 associated with at least one capacitor device 2 and adapted to sense the strain of the capacitor device 2; and at least one electronic control device 10 operationally connected to the strain sensing assembly 9 and operationally configured to receive from the latter at least one first data item, related to the strain of the capacitor device 2, and to process at least one second data item, related to the first data item and indicative of the risk of potential burst of the capacitor device 2.

[0062] The strain sensing assembly 9 is associated with the outer containment body 3 and is adapted to detect a size strain thereof.

[0063] In detail, the first data item sensed by the strain sensing assembly 9 is indicative of the level of size strain achieved by the outer containment body 3.

[0064] The level of strain achieved by the outer containment body 3 is related to the air pressure within it which, in turn, is variable depending on the amount of combustion gases that may be present.

[0065] The electronic control device 10 is configured to compare the first data item received from the strain sensing assembly 9 with a reference strain data item related to a strain limit condition of the outer containment body 3 exceeded which the outer containment body 3 bursts.

[0066] Therefore, if the electronic control device 10 senses that the first data item is less than the strain limit condition, the second data item is indicative of an unlikely burst condition of the capacitor device 2.

[0067] On the other hand, if the electronic control device 10 senses that the first data item is equal to or higher than the strain limit condition, the second data item is indicative of a probable burst condition of the capacitor device 2.

[0068] In this latter case, as will be described in detail below, the burst-proof system 1 is adapted to directly or indirectly operate on the power supply unit of the capacitor device 2 in order to block the passage of current towards the conductive elements of the same capacitor device 2.

[0069] Conveniently, the strain sensing assembly 9 comprises at least one strain gauge 11, 12, 13, 14 associated with the outer containment body 3 of the capacitor device 2 and deformable as a result of the strain of the outer containment body 3. Preferably, the strain gauge 11, 12, 13, 14 is directly associated with the outer containment body 3 by interposition of an adhesive.

[0070] Alternatively, the strain sensing assembly 9 comprises a supporting body associable with the outer containment body 3 and adapted to hold the strain gauge 11, 12, 13, 14.

[0071] As is well known to the technician in the field, the strain gauge 11, 12, 13, 14 is at least partly made of a substantially elastic material, has a substantially extended conformation and extends as a result of the strain of the body with which it is associated.

[0072] With particular reference to the preferred embodiment shown in the figures, the strain gauges 11, 12, 13, 14 deform elastically as a result of the strain of the outer containment body 3 resulting from the pressure increase inside it.

[0073] Conveniently, the strain sensing assembly 9 comprises at least one measuring device 15 associated with the strain gauge 11, 12, 13, 14 and adapted to measure the strain thereof as a result of the strain of the outer containment body 3.

[0074] In other words, the measuring device 15 processes the first data item which is related to the extension of the strain gauge 11, 12, 13, 14 resulting from the strain of the outer containment body 3.

[0075] Preferably, the strain gauge 11, 12, 13, 14 is of the type of an electric resistance strain gauge.

[0076] In the figures, the strain gauge 11, 12, 13, 14 is shown in schematic form for pure representational simplicity.

[0077] The strain gauge 11, 12, 13, 14 comprises a supporting element, made of electrically insulating, elastically deformable material and directly associated with the outer containment body 3, and a circuit board, consisting of an electrically conducting track made locked together with the supporting element. The conducting track consists of a metal filament which is arranged on the supporting element so as to define a path that can be traveled by the electric current.

[0078] In this regard, pads are made at the end of the conducting track for connecting the power and measurement leads.

[0079] The supporting element and the conducting track have a substantially plateshaped and substantially extended conformation.

[0080] As a result of the strain of the outer containment body 3, the strain gauge 11, 12, 13, 14 and, in detail, the supporting element and the conducting track extend and cause a variation in the electrical resistance of the strain gauge 11, 12, 13, 14.

[0081] The variation in the electrical resistance of the strain gauge 11, 12, 13 14 can be measured and related to the magnitude of the strain that caused it, i.e., the force exerted on the outer containment body 3 by the combustion gases inside it in case of extensive combustion of the conductive elements and / or of the insulating element. Preferably, the measuring device 15 is of the type of a Wheatstone bridge connected to the strain gauge 11, 12, 13, 14 and adapted to sense the change in the electrical resistance of the strain gauge 11, 12, 13, 14 as a result of a relevant strain.

[0082] As is familiar to the technician in the field, the Wheatstone bridge is a circuit diagram that is schematically shown in Figure 5 and consists of a current generator, which generates a supply voltage V, and of two resistive branches, which are connected to the current generator and placed in parallel with each other.

[0083] A first resistive branch consists of a first resistor Rl, directly connected to the voltage generator, and of a fourth resistor R4, connected in series to the first resistor Rl.

[0084] The second resistive branch consists of a second resistor R2, directly connected to the current generator, and of a third resistor R3, connected in series to the second resistor R2.

[0085] Under normal operating conditions, the first resistive branch and the second resistive branch have the same electrical resistance, resulting in the fact that at two unpowered ends S- and S+ of the circuit, the same voltage is measured.

[0086] On the other hand, in the event of at least one of the resistors consisting of a strain gauge 11, 12, 13, 14 and in the event of the latter undergoing a variation in length, it is possible to find a variation in the electrical resistance along at least one of the two resistive branches leading to the formation of a difference in potential U between the two ends S- and S+.

[0087] Conveniently, the strain sensing assembly 9 comprises a plurality of strain gauges 11, 12, 13, 14.

[0088] The previously described measuring device 15 can be used to measure the variation in resistance of a plurality of strain gauges 11, 12, 13, 14, in detail up to four strain gauges 11, 12, 13, 14.

[0089] Alternatively, the strain sensing assembly 9 may comprise a plurality of measuring devices 15 wherein each is adapted to measure the variation in resistance of a respective strain gauge 11, 12, 13, 14. In this regard, it is worth noting that three main connection configurations of the Wheatstone Bridge are known, namely: quarter-bridge connection, wherein there is a strain gauge 11, 12, 13, 14 and three completion resistors; half-bridge connection, wherein there are two strain gauges 11, 12, 13, 14 and two completion resistors; full-bridge connection, wherein there are four strain gauges 11, 12, 13, 14.

[0090] The difference in potential U, in the case where there are strain gauges 11, 12, 13, 14 having the same calibration factor K, can be defined by the following formula, where the factors ei, £2, £3, £4 identify the variation in length of each strain gauge 11, 12, 13, 14 and £TOT the total variation in length of all strain gauges 11, 12, 13, 14:

[0091] In light of this, it can be inferred that by measuring the difference in potential U, it is possible to obtain the variation in the length of the strain gauges 11, 12, 13, 14 and from there to trace the stress level on the outer containment body 3.

[0092] Advantageously, the strain sensing assembly 9 comprises at least a first strain gauge 11 associated with the lateral wall 7 of the outer containment body 3, the outer containment body 3 having a substantially cylindrical conformation, the first strain gauge 11 being adapted to sense the strain of the lateral wall 7 along the longitudinal development axis 16 of the outer containment body 3.

[0093] As can be seen from Figure 1, the first strain gauge 11 is associated with the lateral wall 7 so that it is arranged substantially parallel to the longitudinal development axis 16 of the outer containment body 3.

[0094] Under certain conditions of use, it may occur that the outer containment body 3 undergoes axial strain, that is, it deforms along a direction substantially parallel to the longitudinal development axis 16.

[0095] For example, this particular type of strain is detectable when the outer containment body 3 extends, that is, when the top wall 6 moves away from the bottom wall 8.

[0096] In such a case, the first strain gauge 11 extends along the longitudinal development axis 16 and the measuring device 15 associated with the first strain gauge 11 provides a first identification data item of the axial strain level of the outer containment body 3.

[0097] Conveniently, the strain sensing assembly 9 comprises at least a second strain gauge 12 associated with the lateral wall 7 and adapted to sense the strain of the lateral wall 7 transversely to the longitudinal development axis 16.

[0098] As can be seen from Figure 2, the second strain gauge 12 is associated with the lateral wall 7 so that it is arranged transversely, preferably orthogonally, to the longitudinal development axis 16 of the outer containment body 3.

[0099] Under certain conditions of use, it may occur that the outer containment body 3 undergoes radial strain, that is, it deforms along a transverse direction, preferably orthogonal to the relevant longitudinal development axis 16.

[0100] In such a case, the second strain gauge 12 extends transversely, preferably orthogonally, to the longitudinal development axis 16 of the outer containment body 3 and the measuring device 15 associated with the second strain gauge 12 provides a first identification data item of the radial strain level of the outer containment body 3.

[0101] It is possible to say that the synergistic combination of the first strain gauge 11 and of the second strain gauge 12 allows sensing the strain of the outer containment body 3 where the lateral wall 7 is located.

[0102] Conveniently, the strain sensing assembly 9 comprises at least one third strain gauge 13 associated with the bottom wall 8 of the outer containment body 3 and adapted to sense the strain of the bottom wall 8 along the radial development direction 17 of the bottom wall 8.

[0103] The bottom wall 8 has a substantially circular conformation and the radial development direction 17 is substantially parallel to the radius of the bottom wall 8.

[0104] With particular reference to Figure 3, it can be seen that the third strain gauge 13 is associated with the bottom wall 8 so that it is arranged substantially parallel to the radial development direction 17 of the bottom wall 8.

[0105] Under some operating conditions, it may occur that the bottom wall 8 may deform by bulging outwards from the outer containment body 3.

[0106] In such a case, the third strain gauge 13 extends and the measuring device 15 associated therewith can provide a first identification data item of the strain level of the bottom wall 8.

[0107] With particular reference to Figure 3, it can be seen that the strain sensing assembly 9 comprises a plurality of third strain gauges 13, in detail three third strain gauges 13, mutually offset by an angle of amplitude substantially equal to 120°.

[0108] This particular technical expedient also makes it possible to sense any localized strain of the bottom wall 8.

[0109] Figure 4 shows a second embodiment of the burst-proof system 1, wherein the components identical to the first embodiment have the same reference numbers as the first embodiment to the detailed description of which reference is fully made.

[0110] The second embodiment of the burst-proof system 1 differs from the first embodiment mainly in that the strain sensing assembly 9 comprises at least a fourth strain gauge 14 associated with the bottom wall 8 and adapted to sense the strain of the bottom wall 8 transversely to the radial development direction 17. Referring to Figure 4, it can be seen that the fourth strain gauge 14 is associated with the bottom wall 8 so that it is arranged transversely, preferably orthogonal, to the radial development direction 17 of the bottom wall 8.

[0111] The fourth strain gauge 14 undergoes extension if the bottom wall 8 undergoes strain in a transverse direction, preferably orthogonal, to the radial development direction 17.

[0112] With particular reference to the embodiment shown in Figure 4, it can be seen that the strain sensing assembly 9 comprises a plurality of fourth strain gauges 14, in detail three fourth strain gauges 14, mutually spaced away from each other along a circumference defined on the bottom wall 8. This particular technical expedient also allows sensing any localized strain of the bottom wall 8.

[0113] The characteristics of the burst-proof system 1 enunciated and described below are to be considered common to both previously described embodiments.

[0114] Advantageously, the burst-proof system 1 comprises at least one first communication channel 18 of the analog type operationally connected to the strain sensing assembly 9 and adapted to transfer the first data item to the electronic control device 10.

[0115] The first communication channel 18 is operationally connected to the measuring device 15.

[0116] The first data item is of the analog type.

[0117] Conveniently, the burst-proof system 1 comprises at least one second communication channel 19 of the digital type operationally connected to the electronic control device 10 and adapted to transfer the second data item from the electronic control device 10 to at least one outer management unit configured to manage the operation of the power supply unit of the capacitor device 2. Preferably, the second data item is of the digital type.

[0118] According to a preferred embodiment of the burst-proof system 1, the communication protocol used by the first communication channel 18 and by the second communication channel 19 is RS485.

[0119] According to an alternative embodiment of the burst-proof system 1, the communication protocol used by the first communication channel 18 and by the second communication channel 19 is RTU.

[0120] As previously mentioned, in the event of the second data item processed by the electronic control device 10 being indicative of an unlikely burst condition of the capacitor device 2, the outer management unit does not take action in the operation of the power supply unit of the capacitor device 2.

[0121] On the contrary, if the second data item is indicative of a probable burst condition of the capacitor device 2, the outer management unit takes action on the power supply unit of the capacitor device 2 in order to block the passage of current of the latter towards the conductive elements of the same capacitor device 2. Conveniently, the burst-proof system 1 comprises at least one pressure sensor associated with the outer containment body 3 and adapted to sense at least one pressure data item within the outer containment body 3.

[0122] The pressure sensor is operationally connected to the electronic control device 10.

[0123] With particular reference to the preferred embodiment shown in the figures, the pressure sensor is not shown in the figures for pure representational simplicity. Preferably, the pressure sensor is associated with the bottom wall 8.

[0124] The electronic control device 10 compares the pressure value sensed by the pressure sensor with a limit pressure value, which is related with a probable burst condition of the capacitor device 2.

[0125] In the event of the pressure value sensed by the pressure sensor being equal to or higher than the limit pressure value, the electronic control device 10 communicates with the outer management unit in order to take action on the power supply unit of the capacitor device 2.

[0126] Conveniently, the burst-proof system 1 comprises at least one temperature sensor associated with the capacitor device 2 and adapted to sense the temperature of the capacitor device 2.

[0127] The temperature sensor is operationally connected to the electronic control device 10.

[0128] With special reference to the figures, the temperature sensor is not shown for pure representational simplicity.

[0129] During a short circuit the capacitor device 2 can overheat and this temperature rise can greatly affect the ability of the electrical components to transmit the electric current.

[0130] In detail, the value of the difference in potential U can be affected by the temperature of the capacitor device 2.

[0131] Consequently, any variation in the electrical resistance of the strain gauge 11, 12, 13, 14, which can be derived from the value of the difference in potential U, cannot be attributed solely to the strain of the outer containment body 3 but can be affected by the temperature of the capacitor device 2. As will be detailed later on, the electronic control device 10 processes the second data item also taking into account the temperature value sensed by the temperature sensor.

[0132] Preferably, the temperature sensor is of the type of a thermistor.

[0133] As is familiar to the technician in the field, a thermistor is a resistor whose resistance value varies significantly with temperature.

[0134] In detail, the resistance value of the thermistor can be used to quantify the temperature rise of the capacitor device 2 and to compensate for the effects of that temperature on the measured value of the difference in potential U.

[0135] Preferably and as is visible in Figure 6, the burst-proof system 1 comprises a plurality of strain sensing assemblies 9 each of which is associated with a respective capacitor device 2.

[0136] As can be seen in Figure 6, the electronic control device 10 is operationally connected to each of the strain sensing assemblies 9 through the first communication channel 18 and can assess the risk of potential burst for each of the capacitor devices 2 to which the strain sensing assemblies 9 are connected. Conveniently, the burst-proof system 1 comprises a plurality of pressure sensors each of which is associated with the outer containment body 3 of a respective capacitor device 2.

[0137] Each pressure sensor is configured to sense the variation in pressure within the respective outer containment body 3.

[0138] Advantageously, the burst-proof system 1 comprises a plurality of temperature sensors each of which is associated with a respective capacitor device 2 and is adapted to sense the temperature of the respective capacitor device 2.

[0139] Conveniently, the electronic control device 10 is operationally configured to carry out at least the steps of: receiving the first data item from each of the strain sensing assemblies 9 through the first communication channel 18, the first data item being of the analog type; receiving at least one temperature data item from the temperature sensors; processing at least one correction factor of the first data item related to the temperature data item; processing the second data item on the basis of the first data item and of the correction factor, the second data item being of the analog type; digitally converting the second data item; sending the second data item to the outer management unit through the second communication channel 19.

[0140] The correction factor of the first data item allows compensation for the effects of the temperature of the capacitor device 2 on the variation in resistance of the strain gauge 11, 12, 13, 14.

[0141] In this way, the second data item, indicative of the potential burst of the capacitor device 2, is freed from the influence of the temperature and solely indicative of the strain of the outer containment body 3.

[0142] According to another aspect, the present invention relates to a capacitor device 2. The capacitor device 2 comprises: at least one outer containment body 3; at least two conductive elements, made of electrically conductive material, arranged internally to the outer containment body 3 and electrically connected to at least one power supply unit; at least one insulating element made of electrically insulating material, positioned between the conductive elements and arranged internally to the outer containment body 3.

[0143] According to the invention, the capacitor device 2 comprises at least one strain sensing assembly 9 associated with the outer containment body 3 and adapted to sense the strain of the outer containment body 3.

[0144] According to the invention, the strain sensing assembly 9 is operationally connected to at least one electronic control device 10 configured to receive from the strain sensing assembly 9 at least one first data item related to the strain of the outer containment body 3, and to process at least one second data item, related to the first data item and indicative of the risk of potential burst of the capacitor device 2.

[0145] The description of the strain sensing assembly 9 of the capacitor device 2 according to the invention and of the electronic control device 10 associated therewith can be traced in the description of the burst-proof system 1 according to the invention and previously given.

[0146] It has in practice been ascertained that the described invention achieves the intended objects, and in particular the fact is emphasized that the burst-proof system for capacitors and the capacitor device according to the invention enable early detection of a possible explosion of the outer containment body of a capacitor.

[0147] Moreover, the burst-proof system for capacitors according to the invention and the capacitor device according to the invention enable the functionality of the capacitor to be preserved as much as possible if it is affected by the occurrence of a short circuit inside it.

Claims

CLAIMS1) Burst-proof system (1) for capacitors, characterized by the fact that it comprises: at least one strain sensing assembly (9) associated with at least one capacitor device (2) and adapted to sense the strain of said capacitor device (2); and at least one electronic control device (10) operationally connected to said strain sensing assembly (9) and operationally configured to receive from the latter at least one first data item, related to the strain of said capacitor device (2), and to process at least one second data item, related to said first data item and indicative of the risk of potential burst of said capacitor device (2).2) Burst-proof system (1) according to claim 1, characterized by the fact that said strain sensing assembly (9) comprises at least one strain gauge (11, 12, 13, 14) associated with the outer containment body (3) of said capacitor device (2) and deformable as a result of the strain of said outer containment body (3).3) Burst-proof system (1) according to one or more of the preceding claims, characterized by the fact that said strain sensing assembly (9) comprises at least one measuring device (15) associated with said strain gauge (11, 12, 13, 14) and adapted to measure the strain thereof as a result of the strain of said outer containment body (3).4) Burst-proof system (1) according to one or more of the preceding claims, characterized by the fact that said strain gauge (11, 12, 13, 14) is of the type of an electrical resistance strain gauge.5) Burst-proof system (1) according to one or more of the preceding claims, characterized by the fact that said measuring device (15) is of the type of a Wheatstone bridge connected to said strain gauge (11, 12, 13, 14) and adapted to sense the change in electrical resistance of said strain gauge (11, 12, 13, 14) as a result of a relevant strain.6) Burst-proof system (1) according to one or more of the preceding claims, characterized by the fact that said strain sensing assembly (9) comprises a plurality of said strain gauges (11, 12, 13, 14).7) Burst-proof system (1) according to one or more of the preceding claims,characterized by the fact that said strain sensing assembly (9) comprises at least one first strain gauge (11) associated with the lateral wall (7) of said outer containment body (3), said outer containment body (3) having substantially cylindrical conformation, said first strain gauge (11) being adapted to sense the strain of said lateral wall (7) along the longitudinal development axis (16) of said outer containment body (3).8) Burst-proof system (1) according to one or more of the preceding claims, characterized by the fact that said strain sensing assembly (9) comprises at least one second strain gauge (12) associated with said lateral wall (7) and adapted to sense the strain of said lateral wall (7) transversely to said longitudinal development axis (16).9) Burst-proof system (1) according to one or more of the preceding claims, characterized by the fact that said strain sensing assembly (9) comprises at least one third strain gauge (13) associated with the bottom wall (8) of said outer containment body (3) and adapted to sense the strain of said bottom wall (8) along a radial development direction (17).10) Burst-proof system (1) according to one or more of the preceding claims, characterized by the fact that said strain sensing assembly (9) comprises at least one fourth strain gauge (14) associated with said bottom wall (8) and adapted to sense the strain of said bottom wall (8) transversely to said radial development direction (17).11) Burst-proof system (1) according to one or more of the preceding claims, characterized by the fact that it comprises at least one first communication channel (18) of the analog type operationally connected to said strain sensing assembly (9) and adapted to transfer said first data item to said electronic control device (10).12) Burst-proof system (1) according to one or more of the preceding claims, characterized by the fact that it comprises at least one second communication channel (19) of the digital type operationally connected to said electronic control device (10) and adapted to transfer said second data item from said electronic control device (10) to at least one outer management unit configured to managethe operation of one power supply unit of said capacitor device (2).13) Burst-proof system (1) according to one or more of the preceding claims, characterized by the fact that it comprises at least one pressure sensor associated with said outer containment body (3) and adapted to sense at least one pressure data item within said outer containment body (3), said pressure sensor being operationally connected to said electronic control device (10).14) Burst-proof system (1) according to one or more of the preceding claims, characterized by the fact that it comprises at least one temperature sensor associated with said capacitor device (2) and adapted to sense the temperature of said capacitor device (2), said temperature sensor being operationally connected to said electronic control device (10).15) Burst-proof system (1) according to one or more of the preceding claims, characterized by the fact that it comprises a plurality of said strain sensing assemblies (9) each of which is associated with a respective said capacitor device (2).16) Burst-proof system (1) according to one or more of the preceding claims, characterized by the fact that said electronic control device (10) is operationally configured to carry out at least the steps of: receiving said first data item from said strain sensing assembly (9) through said first communication channel (18), said first data item being of the analog type; receiving at least one temperature data item from said temperature sensor; processing at least one correction factor of said first data item related to said temperature data item; processing said second data item on the basis of said first data item and of said correction factor, said second data item being of the analog type; digitally converting said second data item; sending said second data item to said outer management unit through said second communication channel (19).17) Capacitor device (2), comprising: at least one outer containment body (3);at least two conductive elements, made of electrically conductive material, arranged internally to said outer containment body (3) and electrically connected to at least one power supply unit; at least one insulating element made of electrically insulating material, positioned between said conductive elements and arranged internally to said outer containment body (3); characterized by the fact that it comprises at least one strain sensing assembly (9) associated with said outer containment body (3) and adapted to sense the strain of said outer containment body (3), said strain sensing assembly (9) being operationally connected to at least one electronic control device (10) configured to receive from said strain sensing assembly (9) at least one first data item related to the strain of said outer containment body (3), and to process at least one second data item, related to said first data item and indicative of the risk of potential burst of said capacitor device (2).

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