System and method for acoustic detection of dielectric breakdown and partial discharge in an electrical device

Abstract

A system and method for acoustically detecting dielectric breakdown or partial discharge in an electrical device, the system including 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 is configured to receive a signal from the at least one EA transducer and analyze the signal to determine whether the signal includes data associated with acoustic vibrations in a frequency range of dielectric breakdown and / or partial discharge of the electrical device. The applicability of this system includes, but is not limited to, screening of electronic parts or components, lifetime characterization testing of materials and processes, diagnostic methods or aids, enhanced testing of components, assemblies or systems, and in-service monitoring to support preventive or conditional maintenance to avoid problems in service.

Description

Technical Field

[0001] The field of the present disclosure generally relates to systems and methods for detecting dielectric breakdown and / or partial discharge within an electrical device, and more particularly to systems and methods for acoustically detecting dielectric breakdown of an electrical device. Background Art

[0002] At least some known methods for testing dielectric substrates of electrical components such as printed circuit boards or printed wiring boards include subjecting the component to a high direct current (DC) or alternating current (AC) electric field and waiting a predetermined time (e.g., 60 seconds) for dielectric breakdown to occur. During such a test (commonly referred to as a "dielectric withstand test"), if no current above the leakage current is detected within the component, the component can be considered suitable for use because it is assumed that the component is free of physical flaws or defects that could cause dielectric breakdown during normal operation. One drawback of this method is that dielectric breakdown, or even a "partial discharge" that may not fully result in dielectric insulation breakdown, will not occur until and unless cosmic rays (or other ionizing or free electron generating events) impinge on a flaw (e.g., a void or cavity) within the component dielectric. As a result, flaws may not be detected even under test.

[0003] Another technique for testing electrical components can include applying a large alternating current (AC) electric field to the component. During such a test, current spikes within the component can be observed over a period of time, which indicate dielectric breakdown and / or partial discharge within the component. One drawback of this method is that the component under test itself may be subjected to electrical stress beyond its normal operating range by the test procedure, thereby shortening the component's service life. Another drawback is that the test procedure can be time-consuming because the component must be observed over a period of time.

[0004] This background art section is intended to introduce the reader to various aspects of the field that may be relevant to the present disclosure, which will be described and / or claimed below. It is believed that this discussion will help to provide background information to the reader to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read from this perspective and not as an admission of prior art. Summary of the Invention

[0005] In one aspect, a system for acoustically detecting dielectric breakdown or partial discharge of an electrical device is provided. The system includes 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 is configured to execute instructions stored in a memory, which 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; based on the analysis, determine whether the signal received from the at least one EA transducer includes data associated with acoustic vibrations in a frequency range of partial discharge 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 a frequency range of partial discharge.

[0006] In another aspect, an electrical system is provided. The electrical system 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 is configured to execute instructions stored in a memory, which 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; based on the analysis, determine whether the signal received from the at least one EA transducer includes data associated with acoustic vibrations in a frequency range of partial discharge 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 a frequency range of partial discharge.

[0007] In another aspect, a method for acoustically detecting dielectric breakdown or partial discharge of an electrical device is provided. The method includes: receiving, by a controller electrically connected to 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 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 discharge 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 a frequency range of partial discharge.

[0008] There are various improvements to the features mentioned in the above aspects. Further features may also be incorporated into the above aspects. These improvements and additional features may exist alone or in any combination. For example, the various features discussed in connection with any of the illustrated embodiments may be incorporated into any of the above aspects individually or in any combination. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1is a block diagram of an example system for acoustically detecting dielectric breakdown and / or partial discharge in an electrical device;

[0010] Figure 2 is a circuit diagram of another example system for acoustically detecting dielectric breakdown and / or partial discharge in an electrical device;

[0011] Figure 3 is a flowchart showing an example process for acoustically detecting dielectric breakdown and / or partial discharge in an electrical device.

[0012] Figure 4 is Figure 2 a graph of several output waveforms of the system shown in , where there is no dielectric breakdown and / or partial discharge in the electrical device.

[0013] Figure 5 is Figure 2 a graph of several output waveforms of the system shown in , where there is dielectric breakdown and / or partial discharge in the electrical device; and

[0014] Figure 6 is Figure 2 an enlarged graph of several output waveforms of the system shown in , where there is dielectric breakdown and / or partial discharge in the electrical device, and showing the accelerated pressure wave caused by the dielectric breakdown and / or partial discharge of the electrical device.

[0015] Although specific features of various embodiments may be shown in some figures and not in others, this is for convenience only. Any features of any other figure may be combined to reference and / or claim any features of any figure.

[0016] Unless otherwise noted, the figures provided herein are intended to illustrate features of embodiments of the present disclosure. These features are considered applicable to a variety of systems including one or more embodiments of the present disclosure. As such, the figures are not intended to include all conventional features known to those of ordinary skill in the art necessary to practice the embodiments disclosed herein. Detailed Description

[0017] describes systems and methods for acoustically detecting dielectric breakdown and / or partial discharge in an electrical device. In an example embodiment, due to flaws or defects (such as voids or cavities) within the dielectric of the electrical device, partial discharge may occur within or on the surface of the electrical device. The flaw can be considered a dielectric breakdown and / or partial discharge of the electrical device because the flaw will develop over time when the device is operating in the field.

[0018] To detect dielectric breakdown and / or partial discharge, an electroacoustic transducer, such as a contact microphone, can be mechanically coupled to an electrical device, e.g., to the dielectric of the device. The electroacoustic device can be tuned or configured to detect acoustic vibrations in a frequency range associated with partial discharge, where, for example, the partial discharge can cause a mechanical pressure wave within the dielectric, which can be detected by the EA transducer. A controller or processor can receive and analyze the data signal provided by the EA transducer, and if acoustic vibrations (such as frequency spikes) in the frequency range associated with partial discharge occur, the controller can generate an alert to indicate a possible dielectric breakdown and / or partial discharge of the device.

[0019] The technical effects of the systems and methods described herein include at least: (a) acoustically detecting acoustic vibrations representative of partial discharge and / or dielectric breakdown and / or partial discharge using an electroacoustic transducer coupled to the dielectric of an electrical device; (b) detecting one or more circuit characteristics representative of partial discharge and / or dielectric breakdown using a quadrilateral detection circuit; (c) verifying partial discharge and / or dielectric breakdown using the circuit characteristics derived from the quadrilateral detection circuit; (d) verifying partial discharge and / or dielectric breakdown based on a comparison of the peak-to-peak distance of the signal received from the electroacoustic transducer or the gap between the frequency spikes of the peaks; (e) generating an alert, warning, or other indication that a partial discharge and / or dielectric breakdown has occurred.

[0020] Thus, as used herein, the phrase "dielectric breakdown" can refer to an event that results in a full loss of the dielectric or electrical insulator that insulates two or more electrical conductors at different potentials. As used herein, the phrase "destructive discharge" is an electrical event in which the charge and the current it produces (the rate of charge movement) are sufficient to allow a high fault current to flow between electrical conductors at different voltage potentials. In a solid insulation system, a destructive discharge can cause the material to break down, rendering it at least partially unable to provide any insulation between the electrical conductors. In a liquid- or gas-based insulation system, the damage is reversible, but the affected electrical equipment or associated electrical system is tripped or otherwise de-energized through protective action. Dielectric breakdown can also occur on the surface of a device or component, where the insulation is damaged or otherwise defective.

[0021] Accordingly, as used herein, the phrase "partial discharge" can refer to a discharge that only partially bridges the insulation system between conductors when the voltage stress exceeds a critical value. These partial discharges may or may not occur near the conductors. Inside a dielectric structure (such as in the case of a printed wiring board or printed circuit board), defects such as delaminations or voids in an epoxy resin may contain trapped gas. Under sufficient electric field stress and temperature conditions, charges accumulate near or within the voids. In the presence of a sufficient local electric field, the gas becomes ionized, thereby releasing the local charge accumulation through the gas within the void. The heating resulting from the movement of free electrons and ions causes rapid heating of the gas, and then high-voltage pulses are generated. Then, this high-voltage pulse is transmitted as acoustic energy or mechanical energy through the surrounding dielectric structure. The acoustic sensors and transducers described herein are designed to detect and operate at the correct frequencies, and signal processing can be used to detect "partial discharge", "destructive discharge", or "dielectric breakdown". Surface partial discharges are also possible, which may also generate acoustic energy that is transmitted into the dielectric structure, conductors, interfaces, and the surrounding gaseous or liquid dielectrics.

[0022] When a partial discharge occurs within an electrical device, the discharge may cause acoustic vibrations in the electrical device (or its dielectric), which, as described herein, can be detected and analyzed. The vibrations typically resonate in a frequency range of approximately 500 kHz to 250 MHz (although other frequency ranges may also occur).

[0023] Figure 1 is a block diagram of an example system 100 for acoustically detecting dielectric breakdown of an electrical device 102. System 100 includes an electrical device 102 and a controller 108. Electrical device 102 includes a dielectric 104 and an electroacoustic (EA) transducer 106. Controller 108 includes a memory 110 and a processor 112.

[0024] In an example embodiment, dielectric 104 may include any suitable dielectric or dielectric substrate, such as any dielectric composite or multi-layer laminate used in the manufacture of a printed circuit board (PCB), printed wiring board (PWB), rotating machine winding or coil, and / or any other electrical device or circuit.

[0025] Electrical device 102 may also include a plurality of components mounted on dielectric 104 and electrically connected by one or more electrical traces, wires, solder joints, etc. The components included on the electrical device are generally not central to understanding the present disclosure and 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 various other hardware components.

[0026] In at least some embodiments, the electrical device can be operable to control or monitor another system or device, such as a motor, 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 installed in an aerospace system such as an aircraft and controls one or more systems or subsystems of the aircraft or aerospace system.

[0027] The EA transducer 106 is any of a variety of electroacoustic transducers, e.g., a contact microphone, a piezoelectric microphone, or a ceramic piezoelectric microphone, and / or any other EA transducer capable of being mechanically coupled to the electrical device 102 and / or the dielectric 104 and detecting structural acoustic vibrations within the electrical device 102 and / or the dielectric 104. In an example embodiment, the EA transducer 106 is mechanically coupled to the dielectric 104 or another portion of the electrical device 102.

[0028] In some embodiments, more than a single EA transducer 106 can be mechanically coupled to the dielectric 104. For example, multiple EA transducers can be implemented, each tuned to a specified frequency range, or each arranged to “listen” to a particular portion of the dielectric 104. In other embodiments, the EA transducer 106 can include one or more air microphones (sensitive to vibrations in air as opposed to structural vibrations).

[0029] In some embodiments, a single or multiple EA transducers 106 can be mechanically coupled to the dielectric 104 as a permanent part of a large component. For example, a single or multiple EA transducers 106 can be implemented as part of a component, each EA transducer 106 tuned to a specified frequency range, or each EA transducer 106 arranged to “listen” to a particular portion of the dielectric 104. In a printed circuit board embodiment, the discretely mounted EA transducer 106 and associated control and drive circuitry 108, 110, and 112 can be part of a complete printed circuit assembly. This enables “self-monitoring” for faults or degradation during the life of the component and also enables preventive or conditional maintenance or replacement.

[0030] As described in more detail herein, the EA transducer 106 can be configured to detect acoustic vibrations within a specified frequency range and generate an output signal in response. In at least some embodiments, the EA transducer 106 can be selected or configured to detect structural acoustic vibrations within a frequency range associated with dielectric breakdown or electrical breakdown of the dielectric 104. For example, as described above, acoustic vibrations caused by dielectric breakdown or partial discharge (PD) within the dielectric 104 typically resonate within a frequency range of approximately 500 kHz to 250 MHz (although other frequency ranges can be accommodated). As a result, the EA transducer can be configured to detect acoustic vibrations within these high kHz to low MHz ranges.

[0031] In response to detecting an acoustic vibration, the EA transducer 106 can generate an output signal that can include data (e.g., frequency data) indicating that PD has occurred. In some cases, an amplifier or preamplifier can be connected to the EA transducer 106 to amplify the signal output by the EA transducer 106. Similarly, in some embodiments, a filter such as a bandpass filter can be connected to the EA transducer 106 to exclude frequencies not related to PD.

[0032] Figure 2 is a circuit diagram of another example system 200 for acoustically detecting dielectric breakdown and / or partial discharge of an electrical device 102. System 200 is similar to system 100 and includes portions of system 100 described above. System 200 also includes a quadrilateral detection circuit 202. The quadrilateral detection circuit 202 can be a Schering bridge (or a modified version of a Schering bridge), a Wheatstone bridge, and / or another similar circuit.

[0033] The quadrilateral detection circuit 202 can thus include a first branch 204, a second branch 206, a third branch 208, and a fourth branch 210. The electrical characteristics of three of the four branches (e.g., branches 204 - 208) are known. For example, branches 204 - 208 can include one or more capacitors, resistors, and / or inductors, whereby the resistance, inductance, and / or capacitance of branches 204 - 208 can be known. The circuit 102 can be included or connected in the fourth branch 210.

[0034] Thus, it will be appreciated that one or more electrical characteristics of the circuit 102 can be derived by using the known values associated with the first through third branches 204 - 208 and solving for the electrical characteristics of the circuit by using one or more known voltage and current formulas (e.g., Kirchhoff's laws). For example, the data collected from the quadrilateral detection circuit 202 can include the voltage (V1) across the circuit 102, the differential voltage (V d ) between the third branch 208 and the fourth branch 210 (i.e., the circuit 102), and the current (i1-3 )。

[0035] In operation, system 100 and / or system 200 can be used to test for PD (or dielectric breakdown) of the electrical device 102. For example, system 100 or 200 can be used to perform real-time health monitoring of the circuit 102. In another embodiment, system 100 or 200 can be used to test the circuit 102 in a laboratory, for example, in the case where the circuit 102 is removed from the field for testing and analysis.

[0036] Figure 3 is a flowchart showing an example process 300 for acoustic detection of PD and / or dielectric breakdown of the electrical device 102. In the example embodiment, the controller 108 receives a data signal from the EA transducer 106 (step 302). The data signal can include frequency data representing acoustic vibrations detected by the EA transducer 106, if any. For example, in the case of PD occurring, the data signal can include amplitude spikes in the frequency range of dielectric breakdown (see additional description below).

[0037] In response to receiving the data signal, the controller 108 can analyze the data signal (step 304). For example, the controller 108 can analyze the data signal to determine whether there is a frequency spike or a frequency spike has occurred in the frequency range of dielectric breakdown and / or partial discharge (step 306). If such a frequency spike exists, the controller 108 can determine that dielectric breakdown and / or partial discharge has occurred (or may have occurred), and generate an alarm for indication (step 308). The alarm can be provided to the user, for example, on a computer display or as an audible or another type of alarm. On the other hand, if the data signal does not include a frequency spike representative of PD or dielectric breakdown, the controller 108 can continue to monitor the electrical device 102 in real time or substantially in real time, receiving continuous reports from the EA transducer in the time domain (return to step 302).

[0038] In addition, in some embodiments, the controller 108 can use the quadrilateral detection circuit 202 to measure and / or calculate one or more circuit characteristics of the circuit 102. Specifically, as described above, the voltage (V1) across the circuit 102, the differential voltage (V d ) between the third branch 208 and the fourth branch 210 (i.e., the circuit 102) can be determined 1-3) Any of these. This data can be used to independently determine whether PD or dielectric breakdown has occurred, or they can be used in combination with the data signals received from the EA transducer 106 to verify the data received from the EA transducer. For example, if, as described above, the data signal received from the EA transducer 106 includes a frequency spike, the data from the quadrilateral detection circuit can be used to verify that the data spike is caused by PD within the electrical device 102.

[0039] Figure 4 is a graph 400 of several output waveforms of the system 200( Figure 2 ) shown, where no PD occurs within the electrical device 102. Figure 5 is a graph 500 of the output waveform of the system 200, where PD occurs. More specifically, graphs 400 and 500 show the voltage (V1) across the circuit 102, the differential voltage (V d ) between the third branch 208 and the fourth branch 210 (i.e., the circuit 102), the current (i 1-3 ) flowing through the circuit, and the data signal (V EA ) received from the EA transducer 106. In Figure 4 and Figure 5 , V1 has been reduced to one-thousandth of the actual value; this is because a high-voltage probe with a voltage divider is used to measure V1 in these figures.

[0040] To evaluate the data shown in graphs 400 and 500, as described above, and in one embodiment, the controller 108 can determine whether the data signal V EA includes frequency spikes within the frequency range of dielectric breakdown and / or partial discharge. Referring to Figure 5 shows this frequency spike 502. The data signal received from the EA transducer 106 does not include a frequency spike (such as the frequency spike 502) in the graph 400 of Figure 4 (indicating that no PD has occurred). In at least some embodiments, a frequency spike within the range of dielectric breakdown and / or partial discharge indicated on the data signal V EA may be sufficient to conclude that the circuit 102 has experienced some dielectric breakdown and / or partial discharge.

[0041] 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 the voltage V1 across the circuit 102 when the frequency spike 502 occurs according to the curve 500. In this example, V1 is approximately 1840 Vrms at the frequency spike 502. Additionally, the controller 108 may retrieve the thickness of the dielectric 104 from the memory 110 and calculate the electric field E that generates PD in the void or cavity based on the assumed shape of the void or cavity within the dielectric 104. Specifically, the controller 108 may calculate the electric field according to the following formula: In this formula, E is the electric field in the void, e is the relative permittivity of the dielectric, and Eo is the electric field in the dielectric.

[0042] In the above formula, assuming the dielectric thickness is 250 μm, E can be calculated. void is approximately equal to 1.39 x 10 7 V / m.

[0043] As shown above, using the calculated electric field E in the void void , the controller 108 can further use the following formula to determine the estimated void radius:

[0044] In the above formula, a is the estimated void radius, and P is the air pressure within the void in Pascals. Therefore, the controller can substitute the calculated electric field E in the void void and the estimated or measured air pressure P within the void to solve for the estimated void radius.

[0045] In this example, the void radius a calculated based on the data received from the quadrilateral detection circuit 202 is 16 μm.

[0046] Once the void radius a is calculated based on the data collected from the quadrilateral detection circuit 202, the void radius a can 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 the speed of sound stored in the memory 110 is 343 m / s and the period of the frequency spike 502 is 40 ns, the controller 108 can calculate the estimated void radius b to be 13.6 μm.

[0047] The controller 108 can compare the estimated void radius a derived from the quadrilateral detection circuit 202 with the estimated void radius b derived from the data signal received from the EA transducer 106, and if the two estimates are within a certain percentage tolerance of each other, the controller 108 can conclude (or verify) that, as here, the frequency spike 502 actually represents a partial discharge within the electrical device 102. This partial discharge can in turn be generated by the discharge of ionized gas within a void having a radius of approximately 13 - 16 μm.

[0048] Figure 6 Yes Figure 5 The amplified graph 600 of the output waveform shown. Generally, Figure 6 More specifically shows the frequency spike 502 and the accelerated pressure wave generated by the partial discharge. Thus, Figure 6 Shows the voltage (V1) across the circuit 102, the differential voltage (V d ) between the third branch 208 and the fourth branch 210 (i.e., the circuit 102), the current (i 1-3 ) flowing through the circuit 102, and the data signal (V EA ) received from the EA transducer 106.

[0049] On this scale, the controller 108 can perform a third verification that PD has occurred within the dielectric 104 of the electrical device 102. Specifically, as shown, if a frequency spike 502 occurs at time t1, then 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, to a third peak 604 at time t3, and to a fourth peak 606 at time t4.

[0050] Due to the fact that PD releases heat energy within the dielectric 104, the first time gap A between the frequency spike 502 and the first subsequent peak 602 can be measured. Similarly, the second time gap B between the peak 602 and the second subsequent peak 604 can be measured, and the third time gap C between the peak 604 and the third subsequent peak 606 can be measured. Generally, as the speed of sound within the dielectric 104 increases proportionally with the temperature rise generated, it can be expected that the time gap between earlier-occurring peaks and later-occurring peaks will decrease (i.e., it can be expected that in at least some cases, the hotter transmission medium conducts acoustic vibrations at a higher speed).

[0051] Accordingly, to verify that the frequency spike 502 is in fact the result of a partial discharge, the controller 108 can also compare the time gap (e.g., time gap A) between the frequency spike 502 and the subsequent peak 602 with the time gap between the peak 602 and the peak 604 (i.e., time gap B) and / or the time gap between the peak 604 and the peak 606 (i.e., time gap C). If the time gap B and / or the time gap C is less than the time gap A, the controller 108 can determine (or verify) that the frequency spike 502 has occurred as a result of a PD. A similar comparison of the time gap C with the time gap B can also be performed.

[0052] As described more briefly above, some embodiments can include multiple EA transducers 106. Multiple EA transducers 106 can be included for various reasons. For example, in one embodiment, each EA transducer 106 of the multiple EA transducers 106 can be positioned structurally to detect or "listen for" PDs in the region or zone adjacent to the EA transducer 106. In related embodiments, to precisely locate the position of a PD on a dielectric structure, one of the multiple EA transducers 106 can be positioned on the dielectric structure. For example, it will be appreciated that if three EA transducers 106 are positioned on a dielectric structure, the precise position of the PD on the dielectric structure can be geometrically determined (e.g., by triangulation or trilateration) based on the acoustic start times at each EA transducer 106 (i.e., the times at which each EA transducer 106 detects acoustic vibrations).

[0053] The technical effects of the system and method for acoustic detection of dielectric breakdown and / or partial discharge in an electrical device include: (a) acoustically detecting acoustic vibrations representative of partial discharge and / or dielectric breakdown using an electroacoustic transducer coupled to the dielectric of the electrical device; (b) detecting one or more circuit characteristics representative of partial discharge and / or dielectric breakdown using a quadrilateral detection circuit; (c) verifying partial discharge and / or dielectric breakdown using the circuit characteristics derived from the quadrilateral detection circuit; (d) verifying partial discharge and / or dielectric breakdown based on a comparison of the peak-to-peak distance of the signals received from the electroacoustic transducer or the gaps between the frequency spikes of the peaks; and (e) generating an alarm, warning, or other indication indicating that a partial discharge and / or dielectric breakdown has occurred.

[0054] The systems and methods described herein are not limited to the specific embodiments described herein. Rather, the components of the system and / or the steps of the method can be used independently and separately from other components and / or steps described herein.

[0055] Although specific features of various embodiments of the present disclosure may be shown in some figures and not in others, this is for convenience only. In accordance with the principles of the present disclosure, any features of any other figure may be combined to reference and / or claim any features of the figures.

[0056] As used herein, an element or step recited in the singular and preceded by the word "a" or "an" should be understood as not excluding a plurality of elements or steps, unless expressly stated to the contrary. Further, a reference to "one embodiment" or "example embodiment" of the present disclosure is not intended to be construed as excluding the existence of additional embodiments that also incorporate the recited features.

[0057] This written description uses examples to disclose various embodiments, including the best mode, to enable those skilled in the art to practice those embodiments, including making and using any device or system and performing any incorporated 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 do not differ from the literal language of the claims by a substantial amount.

[0058] Note: The following items describe other aspects of the present disclosure.

[0059] Item 1. An electrical system, comprising:

[0060] An electrical device;

[0061] At least one electroacoustic (EA) transducer mechanically coupled to the electrical device and configured to detect acoustic vibrations of the electrical device; and

[0062] A controller electrically connected to the at least one EA transducer, the controller being configured to execute instructions stored in a memory, the instructions when executed causing the controller to at least:

[0063] Receive a signal from the at least one EA transducer;

[0064] Analyze the signal received from the at least one EA transducer;

[0065] Based on the analysis, determine whether the signal received from the at least one EA transducer includes data associated with acoustic vibrations of the electrical device within a frequency range of partial discharge of the electrical device; and

[0066] In response to determining that the signal received from the at least one EA transducer includes data associated with acoustic vibrations within a frequency range of partial discharge, generate an alarm.

[0067] Item 2. The electrical system of Item 1 further includes a quadrilateral detection circuit having four branches, wherein three of the four branches have known resistances, and wherein one of the four branches includes an electrical device, and wherein the quadrilateral detection circuit is electrically connected to a controller.

[0068] Item 3. The electrical system of Item 2, wherein the quadrilateral detection circuit is one of a Wheatstone bridge and a Schering bridge.

[0069] Item 4. The electrical system of Item 2, wherein the instructions, when executed, further cause the controller to at least:

[0070] Receive at least one measurement value from the quadrilateral detection circuit; and

[0071] In response to determining that the signal received from at least one EA transducer includes data associated with acoustic vibrations in the frequency range of partial discharge, verify the determination based on at least one measurement value received from the quadrilateral detection circuit.

[0072] Item 5. The electrical system of Item 4, wherein, in order to verify the determination that the signal received from at least one EA transducer includes data associated with acoustic vibrations in the frequency range of partial discharge, the instructions, when executed, further cause the controller to at least:

[0073] Calculate a first estimate of at least one physical dimension of a void in the dielectric of the electrical device that produces partial discharge, based on the time period of the acoustic vibrations in the frequency range of partial discharge and the speed of sound stored in a memory;

[0074] Calculate the electric field within the void based on at least one measurement value received from the quadrilateral detection circuit, and calculate a second estimate of at least one physical dimension of a void in the dielectric of the electrical device based on the calculated electric field; and

[0075] Compare the first estimate of at least one physical dimension with the second estimate of at least one physical dimension.

[0076] Item 6. The electrical system of Item 1, wherein the electrical device is configured to control an aerospace system, and wherein the frequency range of the ambient noise generated by the aerospace system is lower than the frequency range of partial discharge.

[0077] Item 7. The electrical system of Item 1, wherein the acoustic vibrations are structural vibrations within the dielectric of the electrical device, and wherein the EA transducer is configured to be mechanically coupled to the dielectric of the electrical device to detect the acoustic vibrations.

[0078] Item 8. The electrical system of Item 1, wherein the EA transducer is a contact microphone configured to be mechanically coupled to the dielectric of the electrical device to detect the acoustic vibrations.

[0079] Item 9. The electrical system of Item 1, wherein the EA transducer is a piezoelectric microphone configured to be mechanically coupled to a dielectric of an electrical device to detect acoustic vibrations.

Claims

1. A system for acoustically detecting dielectric breakdown or partial discharge in an electrical device, the system comprising: at least one electroacoustic transducer configured to detect acoustic vibrations of the electrical device; and a controller electrically connected to the at least one electroacoustic transducer; and a quadrilateral detection circuit having four branches, wherein three of the four branches have known resistances, and one of the four branches includes the electrical device, and wherein the quadrilateral detection circuit is electrically connected to the control, wherein the controller is configured to execute instructions stored in a memory, the instructions when executed cause the controller to at least: receive a signal from the at least one electroacoustic transducer; analyze the signal received from the at least one electroacoustic transducer; based on the analysis, determine whether the signal received from the at least one electroacoustic transducer includes data associated with acoustic vibrations in a frequency range of partial discharge of the electrical device; receive at least one measurement value from the quadrilateral detection circuit; in response to determining that the signal received from the at least one electroacoustic transducer includes the data associated with the acoustic vibrations in the frequency range of partial discharge, verify the determination based on the at least one measurement value received from the quadrilateral detection circuit; and in response to determining that the signal received from the at least one electroacoustic transducer includes the data associated with the acoustic vibrations in the frequency range of partial discharge, generate an alarm.

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

3. The system according to claim 1, wherein To verify the determination that the signal received from the at least one electroacoustic transducer includes the data associated with the acoustic vibrations in the frequency range of partial discharge, the instructions when executed further cause the controller to at least: calculate a first estimate of at least one physical dimension of a void in the dielectric of the electrical device that produces partial discharge, based on a time period of the acoustic vibrations in the frequency range of partial discharge and the speed of sound stored in the memory; calculate an electric field within the void based on the at least one measurement value received from the quadrilateral detection circuit, and based on the calculated electric field, calculate a second estimate of at least one physical dimension of the void in the dielectric of the electrical device; and compare the first estimate of the at least one physical dimension with the second estimate of the at least one physical dimension.

4. The system according to claim 1, wherein, The at least one electroacoustic transducer is a contact microphone configured to be mechanically coupled to the dielectric of the electrical device to detect the acoustic vibrations.

5. The system according to claim 1, wherein, The at least one electroacoustic transducer is a piezoelectric microphone configured to be mechanically coupled to the dielectric of the electrical device to detect the acoustic vibrations.

6. The system according to claim 1, wherein The acoustic vibrations are structure-borne acoustic vibrations within the dielectric of the electrical device, and wherein the at least one electroacoustic transducer is configured to be mechanically coupled to the dielectric of the electrical device to detect the acoustic vibrations.

7. A method for acoustically detecting partial discharge in an electrical device, the method comprising: A controller electrically connected to at least one electroacoustic transducer receives a signal from the at least one electroacoustic transducer, the at least one electroacoustic transducer being mechanically coupled to the electrical device and configured to detect acoustic vibrations of the electrical device; The controller analyzes the signal received from the at least one electroacoustic transducer; The controller determines, based on the analysis, whether the signal received from the at least one electroacoustic transducer includes data associated with acoustic vibrations within a frequency range of partial discharge of the electrical device; The controller receives at least one measurement value from a quadrilateral detection circuit having four branches, wherein three of the four branches have known resistances, and one of the four branches includes the electrical device, and wherein the quadrilateral detection circuit is electrically connected to the controller; In response to determining that the signal received from the at least one electroacoustic transducer includes the data associated with the acoustic vibrations within the frequency range of partial discharge, the controller verifies the determination based on the at least one measurement value received from the quadrilateral detection circuit; and In response to determining that the signal received from the at least one electroacoustic transducer includes the data associated with the acoustic vibrations within the frequency range of partial discharge, an alarm is generated.

8. The method according to claim 7, wherein To verify the determination that the signal received from the at least one electroacoustic transducer includes the data associated with the acoustic vibrations within the frequency range of partial discharge, the method further includes: The controller calculates a first estimate of at least one physical dimension of a void in the dielectric of the electrical device that produces the partial discharge, based on a time period of the acoustic vibrations within the frequency range of partial discharge and the speed of sound stored in a memory; The controller calculates an electric field within the void based on the at least one measurement value received from the quadrilateral detection circuit, and calculates a second estimate of the at least one physical dimension of the void in the dielectric of the electrical device based on the calculated electric field; and The controller compares the first estimate of the at least one physical dimension with the second estimate of the at least one physical dimension.

Images