Systems and methods for acoustic detection of dielectric breakdown and partial discharge events in electrical devices - Patents.com

Abstract

To provide a system that accurately detects dielectric breakdown and / or partial discharge in an electrical device in a short time without shortening the operational life of the electrical device.SOLUTION: A system 100 for acoustically detecting dielectric breakdown of, or partial discharge within, or on, an electrical device 100 includes at least one electroacoustic (EA) transducer 106 configured to detect an acoustic vibration of the electrical device 100, and a controller 108 electrically connected to the at least one EA transducer 106. The controller 108 is configured to receive a signal from the at least one EA transducer 106, and analyze the signal to determine whether the signal includes data associated with an acoustic vibration in a frequency range of dielectric breakdown and / or partial discharge of the electrical device 102.SELECTED DRAWING: Figure 1

Description

[Background technology]

[0001] The field of the disclosure relates generally to systems and methods for detecting dielectric breakdown and / or partial discharge in electrical devices, and more particularly to systems and methods for acoustically detecting dielectric breakdown in electrical devices.

[0002] At least some known methods for testing electrical components (such as the dielectric substrate of a printed circuit board or printed wiring board) include exposing the component to a large direct current (DC) or alternating current (AC) electric field and waiting a predetermined time (e.g., 60 seconds) for dielectric breakdown to occur. If no current in excess of the leakage current is detected in the component during this type of test (commonly referred to as a "withstand test"), the component may be deemed suitable for use since it may be deemed to have no physical defects or imperfections that may tend to cause dielectric breakdown during normal operation. One drawback of this method is that dielectric breakdown (even a "partial discharge" that does not necessarily result in breakdown of the dielectric insulator) may not occur until and unless a cosmic ray is projected (or other ionization or free electron generation event occurs) on a defect (e.g., a void or cavity) in the dielectric of the component. As a result, the defect may go undetected even when subjected to testing.

[0003] Another technique for testing electrical components may involve applying a large alternating current (AC) electric field to the component. In this type of test, the component may be observed over a period of time for current spikes that indicate dielectric breakdown and / or partial discharges within the component. One drawback of this method is that the test procedure itself may expose the tested component to electrical stresses beyond its typical operating range, thereby shortening the operating life of the component. Another drawback is that the test procedure may be time consuming since the component must be observed over a period of time.

[0004] This "Background" section is intended to introduce the reader to various aspects of the art that may be related to the present disclosure, which is described and / or claimed below. This description is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these descriptions are to be read in this light, and not as admissions of prior art. Summary of the Invention

[0005] In one aspect, a system for acoustically detecting electrical breakdown or partial discharge in an electrical device is provided, the system including at least one electroacoustic (EA) transducer configured to detect acoustic vibrations in the electrical device, and a controller electrically connected to the at least one EA transducer, the controller configured to execute instructions stored in a memory that, when executed, cause the controller to at least: receive a signal from the at least one EA transducer, analyze the signal received from the at least one EA transducer, determine based on the analysis whether the signal received from the at least one EA transducer includes data associated with acoustic vibrations in a frequency range of partial discharges in the electrical device, and generate an alert in response to determining that the signal received from the at least one EA transducer includes data associated with acoustic vibrations in a frequency range of partial discharges.

[0006] In another aspect, an electrical system is provided that includes an electrical device, at least one electroacoustic (EA) transducer configured to detect acoustic vibrations of the electrical device, and a controller electrically connected to the at least one EA transducer, the controller configured to execute instructions stored in a memory that, when executed, cause the controller to at least: receive a signal from the at least one EA transducer, analyze the signal received from the at least one EA transducer, determine based on the analysis whether the signal received from the at least one EA transducer includes data associated with acoustic vibrations in a partial discharge frequency range of the electrical device, and generate an alert in response to determining that the signal received from the at least one EA transducer includes data associated with acoustic vibrations in the partial discharge frequency range.

[0007] In yet another aspect, a method for acoustically detecting electrical breakdown or partial discharge in an electrical device is provided, the method including receiving, by a controller electrically connected to the at least one electroacoustic (EA) transducer, a signal from the at least one EA transducer, the EA transducer being mechanically coupled to the electrical device and configured to detect acoustic vibrations of the electrical device, analyzing, by the controller, the signal received from the at least one EA transducer, determining, by the controller and based on the analysis, whether the signal received from the at least one EA transducer includes data associated with acoustic vibrations in a partial discharge frequency range of the electrical device, and generating an alert in response to determining that the signal received from the at least one EA transducer includes data associated with acoustic vibrations in the partial discharge frequency range.

[0008] There are various refinements of the features described in relation to the above-mentioned aspects. Also, additional features may be incorporated into the above-mentioned aspects. Such refinements and additional features may exist individually or in any combination. For example, various features described below in relation to any of the illustrated embodiments may be incorporated into any of the above-mentioned aspects, either alone or in any combination. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a block diagram of an exemplary system for acoustically detecting electrical breakdown and / or partial discharge in an electrical device. [Diagram 2] FIG. 2 is a circuit diagram of another exemplary system for acoustically detecting electrical breakdown and / or partial discharge in an electrical device. [Diagram 3] FIG. 1 is a flow diagram illustrating an exemplary process for acoustically detecting electrical breakdown and / or partial discharge in an electrical device. [Figure 4] 3 is a graph of several output waveforms of the system shown in FIG. 2, in which no dielectric breakdown and / or partial discharge of electrical devices occurs; [Diagram 5] 3 is a graph of several output waveforms of the system shown in FIG. 2 in which breakdown and / or partial discharge of an electrical device occurs; [Figure 6] FIG. 3 is an enlarged graph of several output waveforms of the system shown in FIG. 2, in which electrical breakdown and / or partial discharge of an electrical device occurs, illustrating that electrical breakdown and / or partial discharge of the electrical device causes an accelerating pressure wave. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Although specific features of various embodiments may be shown in some drawings and not in others, this is for convenience only, and any feature of any drawing may be referenced and / or claimed in combination with any feature of any other drawing.

[0011] Unless otherwise indicated, the drawings provided herein are intended to illustrate features of embodiments of the present disclosure. Such features may be applicable to a wide variety of systems incorporating one or more embodiments of the present disclosure. As such, the drawings are not intended to include all conventional features known to those of ordinary skill in the art to be required for the practice of the embodiments disclosed herein.

[0012] A system and method for acoustically detecting dielectric breakdown and / or partial discharge in an electrical device is described. In one exemplary embodiment, a partial discharge within or on the surface of an electrical device may occur as a result of a defect or imperfection (such as a void or cavity) in the dielectric of the electrical device. This defect may worsen over time as the device operates in the field, and therefore may be considered a dielectric breakdown and / or partial discharge in the electrical device.

[0013] To detect breakdown and / or partial discharge, an electroacoustic transducer (such as a contact microphone) may be mechanically coupled to the electrical device (e.g., to the dielectric of the device). The electroacoustic device may be tuned or configured to detect acoustic vibrations within a frequency range associated with partial discharge. The partial discharge may, for example, induce mechanical pressure waves in the dielectric that the EA transducer may detect. A controller or processor may receive and analyze the data signal provided by the EA transducer. Upon the occurrence of acoustic vibrations (e.g., a frequency spike) within a frequency range associated with partial discharge, the controller may generate an alarm indicating a possible breakdown and / or partial discharge of the device.

[0014] Technical effects of the systems and methods described herein include at least: (a) acoustic detection of acoustic vibrations indicative of partial discharges and / or dielectric breakdown using an electroacoustic transducer coupled to a dielectric of an electrical device; (b) detection of one or more circuit characteristics indicative of partial discharges and / or dielectric breakdown using a quadrilateral detection circuit; (c) verification of partial discharges and / or dielectric breakdown using the circuit characteristics obtained from the quadrilateral detection circuit; (d) verification of partial discharges and / or dielectric breakdown based on a comparison of the peak-to-peak distance or spacing between frequency spikes of the peaks of the signal received from the electroacoustic transducer; and (e) generation of an alarm, warning, or other indication that partial discharges and / or dielectric breakdown have occurred.

[0015] Thus, as used herein, the term "dielectric breakdown" may refer to an event that results in a complete loss of the dielectric or electrical insulation that separates two or more conductors at different voltage potentials. As used herein, the term "disruptive discharge" is an electrical event in which the charge and resulting current (rate of charge transfer) become sufficient to allow a large fault current to flow between conductors at different voltage potentials. In solid insulation systems, a disruptive discharge may destroy the material, at least partially rendering it unable to provide any separation between the conductors. In liquid- or gas-based insulation systems, the damage is reversible, but the affected electrical equipment or associated electrical system will fail or otherwise be rendered non-current-carrying by a protective action. Dielectric breakdown may also occur on the surface of a device or assembly, where the insulation on such surfaces is weak or otherwise incomplete.

[0016] Thus, as used herein, the term "partial discharge" may refer to a discharge that only partially bridges the insulating system between conductors when voltage stress exceeds a threshold value. Such partial discharges may or may not occur adjacent to the conductors. Within dielectric structures (e.g., in printed wiring boards or printed circuit boards), defects such as epoxy delaminations or voids may contain trapped gas. Under sufficient electric field stress and temperature, charge may accumulate adjacent to or within the voids. In the presence of a sufficient local electric field, the gas may be ionized, allowing release of local charge accumulation through the gas within the void. Heating caused by the movement of free electrons and ions results in rapid heating of the gas, which then generates a high voltage pulse. This high voltage pulse is then transmitted through the surrounding dielectric structure as acoustic or mechanical energy. The acoustic sensors and transducers described herein are designed for the appropriate frequencies to detect and signal processing can be used to detect "partial discharges", "disruptive discharges", or "dielectric breakdown". Surface partial discharges are also possible, which can generate acoustic energy. The acoustic energy is transferred into dielectric structures, into conductors, at interfaces, and even in surrounding gas or liquid dielectrics.

[0017] When a partial discharge occurs in an electrical device, the discharge may induce acoustic vibrations in the electrical device (or its dielectric), which may be detected and analyzed as described herein. The vibrations may typically resonate in a frequency range of approximately 500 kHz to 250 MHz, but may also be in other frequency ranges.

[0018] 1 is a block diagram of an exemplary system 100 for acoustically detecting dielectric breakdown in an electric device 102. The system 100 includes an electric device 102 and a controller 108. The electric device 102 includes a dielectric 104 and an electroacoustic (EA) transducer 106. The controller 108 includes a memory 110 and a processor 112.

[0019] In this exemplary embodiment, dielectric 104 may include any suitable dielectric or dielectric substrate (e.g., any dielectric composite or dielectric multi-layer laminate used in the manufacture of a printed circuit board (PCB), a printed wiring board (PWB), a winding or coil of a rotating machine, and / or any other electrical device or circuit).

[0020] The electrical device 102 may also include a number of components attached to the dielectric 104 and electrically connected by one or more electrical traces, wires, solder joints, etc. These components included in the electrical device are generally not central to understanding this disclosure, but may include, for example, one or more resistors, one or more capacitors, one or more inductors, one or more switching devices (e.g., transistors, MOSFETs, IGBTs, BJTs, etc.), and / or a wide variety of other hardware components.

[0021] In at least some embodiments, the electrical device may be operable to control or monitor another system or device (e.g., a monitor, an air compressor, a control panel or display, and / or any other desired device or system). Additionally, in at least some embodiments, the electrical device 102 is onboard an aerospace-related system (such as an aircraft) and controls one or more systems or subsystems of the aircraft or aerospace-related system.

[0022] EA transducer 106 may be any of a wide variety of electroacoustic transducers, such as a contact microphone, a piezoelectric microphone, or a ceramic piezoelectric microphone, and / or any other EA transducer that is mechanically coupled to electrical device 102 and / or dielectric 104 and capable of detecting structural acoustic vibrations within electrical device 102 and / or dielectric 104. In this exemplary embodiment, EA transducer 106 is mechanically coupled to dielectric 104 or another portion of electrical device 102.

[0023] In some embodiments, more than one EA transducer 106 may be mechanically coupled to the dielectric 104. For example, multiple EA transducers may be implemented, each tuned to a particular frequency range or each positioned to "listen to" a particular portion of the dielectric 104. In other embodiments, the EA transducer 106 may include one or more air microphones (which are sensitive to air vibrations rather than structural vibrations).

[0024] In some embodiments, the EA transducer 106 or transducers 106 may be mechanically coupled to the dielectric 104 as a permanent component of a larger assembly. For example, a single or multiple EA transducers 106, each tuned to a particular frequency range or positioned to "listen" to a particular portion of the dielectric 104, may be implemented as part of the assembly. In a printed circuit board embodiment, the separately mounted EA transducer 106 and associated control and drive circuits 108, 110, and 112 may be part of the finished printed circuit assembly. This allows for "self-monitoring" of failures or damage during the life of the assembly, which may also allow for preventative or condition-based maintenance or replacement.

[0025] As described in detail herein, the EA transducer 106 may be configured to detect acoustic vibrations within a particular frequency range and generate an output signal accordingly. In at least some embodiments, the EA transducer 106 may be selected or configured to detect structural acoustic vibrations within a frequency range associated with a dielectric breakdown or electrical breakdown of the dielectric 104. For example, as described above, acoustic vibrations caused by a dielectric breakdown or partial discharge (PD) in the dielectric 104 may generally resonate in a frequency range of approximately 500 kHz to 250 MHz (although other frequency ranges may also be applicable). As a result, the EA transducer may be configured to detect acoustic vibrations within such high kilohertz to low megahertz range.

[0026] In response to detecting the acoustic vibrations, the EA transducer 106 may generate an output signal. The output signal may include data (e.g., frequency data) indicative of the occurrence of PD. In some cases, an amplifier or pre-amplifier may be coupled to the EA transducer 106 to amplify the signal output by the EA transducer 106. Similarly, in some embodiments, a filter (such as a band-pass filter) may be coupled to the EA transducer 106 to filter out frequencies not associated with PD.

[0027] 2 is a circuit diagram of another example system 200 for acoustically detecting electrical breakdown and / or partial discharge in an electrical device 102. System 200 is similar to system 100 and includes the components of system 100 described above. System 200 also includes a quadrilateral detection circuit 202. Quadrilateral detection circuit 202 may be a Schering bridge (or a variation of a Schering bridge), a Wheatstone bridge, and / or other similar circuits.

[0028] Thus, the quadrilateral detection circuit 202 may include a first leg 204, a second leg 206, a third leg 208, and a fourth leg 210. The electrical characteristics of three of the four legs (e.g., legs 204-208) may be known. For example, legs 204-208 may include one or more capacitors, resistors, and / or inductors such that the electrical resistance, inductance, and / or capacitance of legs 204-208 may be known. The electrical circuit 102 may be included in or connected to the fourth leg 210.

[0029] Thus, it will be appreciated that one or more electrical characteristics of the electrical circuit 102 may be obtained using known values ​​associated with the first through third legs 204-208, and by determining the electrical characteristics of the electrical circuit using one or more known voltage-current equations (such as Kirchhoff's Laws). For example, data collected from the quadrilateral detection circuit 202 may include the voltage across the electrical circuit 102 (V1), the differential voltage between the third leg 208 and the fourth leg 210 (i.e., the electrical circuit 102) (V d ), and the current passing through the electrical circuit 102 (i 1-3 ).

[0030] System 100 and / or system 200 may be used to test electrical device 102 for PD (or dielectric breakdown) while in service. For example, system 100 or 200 may be used to perform real-time health monitoring of electrical circuit 102. In another embodiment, system 100 or 200 may be used to test electrical circuit 102 in a testing laboratory (e.g., such as when electrical circuit 102 is removed from the field for testing and analysis).

[0031] 3 is a flow diagram illustrating an example process 300 for acoustically detecting PD and / or breakdown in an electrical device 102. In this example embodiment, the controller 108 receives a data signal from the EA transducer 106 (step 302). The data signal may include frequency data representative of any acoustic vibrations detected by the EA transducer 106. For example, if PD occurs, the data signal may include an amplitude spike in the frequency range of the breakdown (see further discussion below).

[0032] In response to receiving the data signal, the controller 108 may analyze the data signal (step 304). For example, the controller 108 may analyze the data signal to determine whether a frequency spike is present or has occurred within a frequency range of breakdown and / or partial discharge (spike 306). If such a frequency spike is present, the controller 108 may determine that breakdown and / or partial discharge has occurred and may generate an alarm indicating so (step 308). The alarm may be provided to a user, for example, on a computer display or as an audible or other type of alarm. On the other hand, if the data signal does not include a frequency spike indicative of PD or breakdown, the controller 108 may receive continuous reports from the EA transducer within this time domain while continuously monitoring the electrical device 102 in real time or substantially real time (returning to step 302).

[0033] Additionally, in some embodiments, one or more circuit characteristics of the electrical circuit 102 may be measured and / or calculated by the controller 108 using the quadrilateral detection circuit 202. Specifically, as described above, the voltage across the electrical circuit 102 (V1), the differential voltage between the third leg 208 and the fourth leg 210 (i.e., the electrical circuit 102) (V d ), and the current passing through the electrical circuit 102 (i 1-3) may be identified. These data may be used to determine whether PD or breakdown has occurred individually, or may be used in conjunction with the data signal received from the EA transducer 106 to corroborate the data received from the EA transducer. For example, if the data signal received from the EA transducer 106 contains a frequency spike as described above, data from the quadrilateral detection circuitry may be used to corroborate that the data spike was caused by a PD in the electrical device 102.

[0034] 4 is a graph 400 of several output waveforms of system 200 (shown in FIG. 2) where no PD has occurred in electrical device 102. FIG. 5 is a graph 500 of output waveforms of system 200 where PD has occurred. More specifically, graphs 400 and 500 show the voltage across electrical circuit 102 (V1), the differential voltage between third leg 208 and fourth leg 210 (i.e., electrical circuit 102) (V d ), the current passing through the electric circuit 102 (i 1-3 ), and the data signal received from the EA transducer 106 (V EA ) In Figures 4 and 5, V1 is reduced to a factor of one thousand of its actual value because in these figures a high voltage probe with a voltage divider was used to measure V1.

[0035] To evaluate the data shown in graphs 400 and 500, in one embodiment, the controller 108 calculates the data signal (V EA ) includes a frequency spike within the frequency range of dielectric breakdown and / or partial discharge. Referring to FIG. 5, such a frequency spike 502 is shown. In the graph 400 of FIG. 4, the data signal received from the EA transducer 106 does not include a frequency spike (such as frequency spike 502), indicating that PD is not occurring. In at least some embodiments, the data signal (V EA) may be sufficient to conclude that some breakdown and / or partial discharge has occurred in the electrical circuit 102.

[0036] In another embodiment, the controller 108 may verify whether PD or dielectric breakdown has occurred based on data received or collected from the quadrilateral detection circuit 202. For example, the controller 108 may determine from the graph 500 the voltage (V1) across the electrical circuit 102 when the frequency spike 502 occurs. In this example, V1 at the time of the frequency spike 502 is approximately 1840 Vrm. In addition, the controller 108 may retrieve the thickness of the dielectric 104 from the memory 110 and calculate the electric field (E) in the void or cavity that caused the PD based on the assumed shape of the void or cavity in the dielectric 104. Specifically, the controller 108 may calculate the electric field from the following equation: E = E ∑ i = 1 ...

[0037] In the above equation, assuming the dielectric thickness is 250 μm, E void is approximately 1.39 × 10 7 This can be calculated to be equal to V / m.

[0038] The controller 108 controls the electric field (E void ) may be used to further determine the estimated void radius using the following equation:

[0039] In the above equation, a is the estimated void radius and P is the air pressure inside the void (in Pascals). Therefore, the controller multiplies the calculated electric field inside the void (E void ) and the estimated or measured air pressure in the void (P).

[0040] In this example, the void radius (a) calculated from the data received from the quadrilateral detection circuit 202 is 16 μm.

[0041] Once the void radius (a) is calculated from the data collected from the quadrilateral detection circuit 202, this void radius (a) may be verified by calculating or estimating the duration or period of the frequency spike 502 and dividing the period of the frequency spike 502 by the speed of sound stored in the memory 110. For example, if a speed of sound of 343 m / s is stored in the memory 110 and the period of the frequency spike 502 is 40 ns, the controller 108 may calculate an estimated void radius (b) of 13.6 μm.

[0042] The controller 108 may compare the estimated void radius (a) obtained from the quadrilateral detection circuit 202 with the estimated void radius (b) obtained from the data signal received from the EA transducer 106. If the two estimates are within a certain percentage tolerance of each other, the controller 108 may now conclude (or verify) that the frequency spike 502 does indeed represent a partial discharge in the electrical device 102. That is, the partial discharge may be caused by a discharge through an ionized gas in a void having a radius of approximately 13-16 μm.

[0043] FIG 6 is a magnified graph 600 of the output waveform shown in FIG 5. FIG 6 generally details the frequency spike 502 and accelerated pressure wave caused by the partial discharge. Thus, FIG 6 shows the voltage across the electrical circuit 102 (V1), the differential voltage between the third leg 208 and the fourth leg 210 (i.e., the electrical circuit 102) (V d ), the current passing through the electric circuit 102 (i 1-3 ), and the data signal received from the EA transducer 106 (V EA ) is shown.

[0044] At this scale, the controller 108 may perform a third verification that PD has occurred within the dielectric 104 of the electrical device 102. Specifically, as shown, when the frequency spike 502 occurs at time t1, the acoustic vibrations within the dielectric 104 (or within the air contained in the void, if an air microphone is used) oscillate to a second peak 602 at time t2, a third peak 604 at time t3, and a fourth peak 606 at time t4.

[0045] As a result of the fact that the PD releases thermal energy within the dielectric 104, a first time interval (A) may be measured between the frequency spike 502 and the first subsequent peak 602. Similarly, a second time gap (B) between the peak 602 and the second subsequent peak 604, and a third time gap (C) between the peak 604 and the third subsequent peak 606 may also be measured. In general, the time gap between an earlier and later occurring peak may be expected to decrease as the speed of sound within the dielectric 104 increases in proportion to the resulting temperature increase (i.e., at least in some cases, the more the transmission medium heats up, the faster acoustic vibrations may be expected to be conducted).

[0046] Thus, the controller 108 may also compare the time gap between the frequency spike 502 and the subsequent peak 602 (e.g., time gap A) with the time gap between peak 602 and peak 604 (i.e., time gap B) and / or the time gap between peak 604 and peak 606 (i.e., time gap C) to verify that the frequency spike 502 was indeed the result of a partial discharge. If time gap B and / or time gap C are less than time gap A, the controller 108 may determine (or verify) that the frequency spike 502 occurred as a result of PD. A similar comparison of time gap C and time gap B may also be performed.

[0047] As briefly described above, some embodiments may include multiple EA transducers 106. Multiple EA transducers 106 may be included for a variety of reasons. For example, in one embodiment, each EA transducer 106 of the multiple EA transducers 106 may be placed on a structure to detect or "listen" for PD in a region or zone proximal to that EA transducer 106. In a related embodiment, multiple EA transducers 106 may be placed on a dielectric structure for the purpose of pinpointing the location of PD in the dielectric structure. For example, it will be appreciated that if three EA transducers 106 are placed on a dielectric structure, the precise location of PD in the dielectric structure may be geometrically determined (e.g., by triangulation or trilateration) based on the time of acoustic arrival at each EA transducer 106 (i.e., the time when each EA transducer 106 detects acoustic vibrations).

[0048] Technical effects of the systems and methods for acoustically detecting partial discharge and / or electrical breakdown in an electrical device include: (a) acoustic detection of acoustic vibrations indicative of partial discharge and / or electrical breakdown using an electroacoustic transducer coupled to a dielectric of an electrical device; (b) detection of one or more circuit characteristics indicative of partial discharge and / or electrical breakdown using a quadrilateral detection circuit; (c) verification of partial discharge and / or electrical breakdown using the circuit characteristics obtained from the quadrilateral detection circuit; (d) verification of partial discharge and / or electrical breakdown based on a comparison of the peak-to-peak distance or spacing between frequency spikes of the peaks of the signal received from the electroacoustic transducer; and (e) generation of an alarm, warning, or other indication that partial discharge and / or electrical breakdown has occurred.

[0049] The systems and methods described herein are not limited to the specific embodiments described herein, but rather the system components and / or method steps may be utilized separately from the other components and / or steps described herein.

[0050] Although specific features of various embodiments of the disclosure may be shown in some drawings and not in others, this is for convenience only, and in accordance with the principles of the disclosure, any feature of a drawing may be referenced and / or claimed in combination with any feature of any other drawing.

[0051] As used herein, an element or step described in the singular and followed by the word "a" or "an" is to be understood as not excluding a plural of that element or step, unless such exclusion is expressly stated. Furthermore, references to "one embodiment" or "an embodiment" of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.

[0052] This specification uses examples to disclose various embodiments, including the best mode, and to enable any person skilled in the art to practice such embodiments, including making and using any device or system, and performing any integrated method. The patentable scope is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements that differ only insignificantly from the literal language of the claims.

[0053] NOTE: The following clauses describe further aspects of the present disclosure.

[0054] Article 1. An electrical device; at least one electroacoustic (EA) transducer mechanically coupled to the electrical device and configured to detect acoustic vibrations of the electrical device; a controller electrically connected to the at least one EA transducer and configured to execute instructions stored in the memory, the instructions, when executed, causing the controller to at least: Receiving a signal from at least one EA transducer; Analyzing a signal received from at least one EA transducer; determining whether the signal received from the at least one EA transducer includes data related to acoustic vibrations of the electrical device within a frequency range of partial discharges of the electrical device based on the analysis; and generating an alarm in response to determining that a signal received from the at least one EA transducer includes data related to acoustic vibrations within a partial discharge frequency range.

[0055] Article 2. The electrical system of clause 1, further comprising a quadrilateral detection circuit having four legs, three of the four legs having known electrical resistance and one of the four legs including an electrical device, the quadrilateral detection circuit electrically connected to the controller.

[0056] Article 3. 3. The electrical system of claim 2, wherein the quadrilateral detection circuit is one of a Wheatstone bridge and a Schering bridge.

[0057] Article 4. The instructions, when executed, cause the controller to at least: receiving at least one measurement from a quadrilateral detection circuit; The electrical system of clause 2, further comprising: in response to a determination that the signal received from the at least one EA transducer includes data related to acoustic vibrations within a partial discharge frequency range, verifying the determination based on at least one measurement value received from the quadrilateral detection circuit.

[0058] Article 5. To verify a determination that a signal received from the at least one EA transducer includes data related to acoustic vibrations within a partial discharge frequency range, the instructions, when executed, may include instructions for causing the controller to at least: calculating a first estimate of at least one physical dimension of a void in a dielectric of the electrical device from a duration of the acoustic vibrations in a frequency range of the partial discharge and the sound speed stored in the memory; calculating an electric field within the void from the at least one measurement received from the quadrilateral detection circuit, and calculating a second estimate of at least one physical dimension of the void within the dielectric of the electrical device from the calculated electric field; 5. The electrical system of claim 4, further comprising: comparing the first estimate of the at least one physical dimension to the second estimate of the at least one physical dimension.

[0059] Article 6. 13. The electrical system of claim 1, wherein the electrical device is configured to control an aerospace-related system, the aerospace-related system generating ambient noise in a frequency range lower than the frequency range of partial discharges.

[0060] Article 7. 13. The electrical system of claim 1, wherein the acoustic vibrations are structural in a dielectric of the electrical device, and the EA transducer is mechanically coupled to the dielectric of the electrical device and configured to detect the acoustic vibrations.

[0061] Article 8. 2. The electrical system of claim 1, wherein the EA transducer is a contact microphone mechanically coupled to a dielectric of the electrical device and configured to detect acoustic vibrations.

[0062] Article 9. 2. The electrical system of claim 1, wherein the EA transducer is a piezoelectric microphone mechanically coupled to a dielectric of the electrical device and configured to detect acoustic vibrations.

Claims

1. 1. A system for acoustically detecting electrical breakdown or partial discharge in an electrical device, comprising: at least one electroacoustic (EA) transducer configured to detect acoustic vibrations of the electrical device; a controller electrically connected to the at least one EA transducer; a quadrilateral detection circuit having four legs, three of the four legs having known electrical resistance, one of the four legs including the electrical device, the quadrilateral detection circuit electrically connected to the controller; Equipped with The controller is configured to execute instructions stored in a memory that, when executed, cause the controller to perform at least: receiving a signal from the at least one EA transducer; analyzing the signal received from the at least one EA transducer; determining whether the signal received from the at least one EA transducer includes data related to acoustic vibrations within a frequency range of partial discharges of the electrical device based on the analysis; receiving at least one measurement from the quadrilateral detection circuit; responsive to determining that the signal received from the at least one EA transducer includes the data related to the acoustic vibration within a frequency range of the partial discharge, verifying the determination based on the at least one measurement received from the quadrilateral detection circuit; generating an alarm in response to determining that the signal received from the at least one EA transducer includes the data related to the acoustic vibration within a frequency range of the partial discharge.

2. 2. The system of claim 1, wherein the quadrilateral detection circuit is one of a Wheatstone bridge and a Schering bridge.

3. To verify the determination that the signal received from the at least one EA transducer includes the data related to the acoustic vibration within a frequency range of the partial discharge, the instructions, when executed, cause the controller to at least: calculating a first estimate of at least one physical dimension of a void in a dielectric of the electrical device generating a partial discharge from a duration of the acoustic vibration within a frequency range of the partial discharge and the sound speed stored in the memory; calculating an electric field within the void from the at least one measurement received from the quadrilateral detection circuitry, and calculating from the calculated electric field a second estimate of the at least one physical dimension of the void within the dielectric of the electrical device; The system of claim 1 , further comprising: comparing the first estimate of the at least one physical dimension to the second estimate of the at least one physical dimension.

4. The system of claim 1 , wherein the EA transducer is a contact microphone mechanically coupled to a dielectric of the electrical device and configured to detect the acoustic vibrations.

5. 2. The electrical system of claim 1, wherein the EA transducer is a piezoelectric microphone mechanically coupled to a dielectric of the electrical device and configured to detect the acoustic vibrations.

6. 2. The electrical system of claim 1, wherein the acoustic vibrations are structural in a dielectric of the electrical device, and the EA transducer is mechanically coupled to the dielectric of the electrical device and configured to detect the acoustic vibrations.

7. 1. A method for acoustically detecting partial discharges in an electrical device, comprising: receiving a signal from at least one electroacoustic (EA) transducer by a controller electrically connected to the at least one EA transducer, the EA transducer being mechanically coupled to the electrical device and configured to detect acoustic vibrations of the electrical device; analyzing, by the controller, the signal received from the at least one EA transducer; determining, by the controller and based on the analysis, whether the signal received from the at least one EA transducer includes data related to acoustic vibrations within a frequency range of partial discharges of the electrical device; receiving, by the controller, at least one measurement from a quadrilateral detection circuit having four legs, three of the four legs having known electrical resistance, one of the four legs including the electrical device, the quadrilateral detection circuit being electrically connected to the controller; in response to determining that the signal received from the at least one EA transducer includes the data related to the acoustic vibration within a frequency range of the partial discharge, verifying, by the controller, the determination based on the at least one measurement received from the quadrilateral detection circuit; generating an alarm in response to determining that the signal received from the at least one EA transducer includes the data related to the acoustic vibrations within a frequency range of the partial discharge.

8. to verify the determination that the signal received from the at least one EA transducer includes the data related to the acoustic vibration within a frequency range of the partial discharge; calculating, by the controller, a first estimate of at least one physical dimension of a void in a dielectric of the electrical device generating the partial discharge from a duration of the acoustic vibration within a frequency range of the partial discharge and the speed of sound stored in a memory; calculating, by the controller, an electric field within the void from the at least one measurement received from the quadrilateral detection circuit, and calculating from the calculated electric field a second estimate of the at least one physical dimension of the void within the dielectric of the electrical device; The method of claim 7 , further comprising comparing, by the controller, the first estimate of the at least one physical dimension to the second estimate of the at least one physical dimension.

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