Patent Description:
At least some known methods for testing an electrical component, such as a dielectric substrate of a printed circuit board or printed wiring board, include subjecting the component to a high direct current (DC) or alternating current (AC) electric field and waiting a predetermined time (e.g., <NUM> seconds) for dielectric breakdown to occur. During this type of test (generally referred to as a "withstand test"), if no electrical current is detected within the component above a leakage current, the component may be deemed acceptable for use, in that the component may be deemed to exclude physical imperfections or defects that may tend to cause dielectric breakdown during normal operation. One disadvantage of this method is that dielectric breakdown, or even a "partial discharge" that doesn't fully result in a breakdown of the dielectric insulation, may not occur until and unless a cosmic ray (or other ionizing or free-electron producing event) is incident upon an imperfection (e.g., a void or cavity) within the dielectric of the component. As a result, even under test, imperfections may not be detected.

Another technique for testing an electrical component may include the application of a large alternating current (AC) electric field to the component. During this type of test, the component may be observed, over a period of time, for current spikes indicative of dielectric breakdown and/or partial discharge within the component. One disadvantage of this method is that the component under test may be subject by the test procedure itself to electrical stress in excess of a typical operational range, thereby shortening the operational life of the component. Another disadvantage is that the test procedure may be time consuming, in that the component must be observed for some period of time.

This Background section is intended to introduce the reader to various aspects of art that may be related to the present disclosure, which are described and/or claimed below.

<CIT>, in accordance with its abstract, states: A system for detecting partial discharge in electrical components may include a control system that may operate a drive in an industrial automation system. The industrial automation system may include the electrical components being analyzed for partial discharge. The system may also include one or more acoustic sensors that may detect one or more acoustic waveforms generated within at least one of the electrical components. The system may also include a monitoring system that may receive the acoustic waveforms from the acoustic sensors and determine whether the one electrical component is experiencing partial discharge based on the acoustic waveforms. The monitoring system may then send a notification to the control system when the one electrical component is determined to be experiencing partial discharge, such that the notification indicates that the one electrical component is experiencing partial discharge.

<CIT>, in accordance with its abstract, states: A method for diagnosing a fault in an electrical component using a diagnostic system having a plurality of sensors. The method includes positioning the electrical component in a predetermined position adjacent the diagnostic system and at a predetermined orientation with respect to the diagnostic system. The method also includes causing a predetermined level of electrical current to flow to the electrical component, the stationary sensors sensing electrical discharge emitted by the electrical component at an area of the fault, and the tangible computerized controller receiving sensor data from the sensors. The method further includes the tangible computerized controller executing the computer-readable instructions to process the sensor data to generate test information including a location of the electrical component at which the fault is occurring in at least two dimensions.

In one aspect, as defined in claim <NUM>, 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 an acoustic vibration 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; determine, based upon the analyzing, whether the signal received from the at least one EA transducer includes data associated with an acoustic vibration in the frequency range of partial discharge of the electrical device; and in response to determining that the signal received from the at least one EA transducer includes the data associated with the acoustic vibration in the frequency range of partial discharge, generate an alert.

In another aspect, as defined in claim <NUM>, 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 mechanically coupled to the electrical device and configured to detect an acoustic vibration of the electrical device; analyzing, by the controller, the signal received from the at least one EA transducer; determining, by the controller and based upon the analyzing, whether the signal received from the at least one EA transducer includes data associated with an acoustic vibration in the frequency range of partial discharge of the electrical device; and in response to determining that the signal received from the at least one EA transducer includes the data associated with the acoustic vibration in the frequency range of partial discharge, generating an alert.

Various refinements exist of the features noted in relation to the above-mentioned aspects. Further features may also be incorporated in the above-mentioned aspects as well. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to any of the illustrated embodiments may be incorporated into any of the above-described aspects, alone or in any combination.

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

Systems and methods for acoustically detecting dielectric breakdown and/or partial discharge of an electrical device are described. In an example embodiment, partial electrical discharge within, or on the surface of, an electrical device may occur as a result of an imperfection or defect, such as a void or cavity, within a dielectric of the electrical device, where the imperfection may be regarded as a dielectric breakdown and/or partial discharge of the electrical device, in that the imperfection may develop over time as the device is operational in the field.

To detect dielectric breakdown and/or partial discharge, an electroacoustic transducer, such as a contact microphone, may be mechanically coupled to the electrical device, such as, for example, to the dielectric of the device. The electroacoustic device may be tuned or configured to detect acoustic vibrations in a frequency range associated with partial discharge, where, for example, partial discharge may induce a mechanical pressure wave within the dielectric, which the EA transducer may detect. A controller or processor may receive and analyze a data signal provided by the EA transducer, and if an acoustic vibration, such as a frequency spike, in the range of frequencies associated with partial discharge occurs, the controller may generate an alert to indicate possible dielectric breakdown and/or partial discharge of the device.

Technical effects of the systems and methods described herein include, at least: (a) acoustic detection, using an electroacoustic transducer coupled to a dielectric of an electrical device, of an acoustic vibration representative of partial discharge and/or dielectric breakdown and/or partial discharge; (b) detection, using a quadrilateral detection circuit, of one or more circuit characteristics representative of partial discharge and/or dielectric breakdown; (c) verification, using the circuit characteristics derived from the quadrilateral detection circuit, of partial discharge and/or dielectric breakdown; (d) verification of partial discharge and/or dielectric breakdown based upon comparison of peak-to-peak distances or gaps between frequency spikes of peaks of a signal received from the electroacoustic transducer; and (e) generation of an alert, warning, or other indication that partial discharge and/or dielectric breakdown have occurred.

As used herein, the phrase "dielectric breakdown" may therefore refer to an event that results in the full loss of a dielectric or electrical insulator to insulate two or more electrical conductors of different potential. As used herein, the phrase "disruptive discharge" is an electrical event where electrical charge and its resultant current (rate of charge movement) is sufficient to enable high fault current to flow between electrical conductors of different voltage potentials. In solid insulation systems, disruptive discharges may breakdown the material rendering it at least partially incapable of providing any isolation between electrical conductors. In liquid or gas based insulation systems, the damage is reversible but the affected electrical equipment or associated electrical system are disrupted or otherwise de-energized through protective action. Dielectric breakdown can also occur on the surface of the device or assembly, where insulation has been compromised or otherwise defective.

As used herein, the phrase "partial discharge" may therefore refer to an electric 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 adjacent to a conductor. Internal to a dielectric structure, such as in the case in a printed wiring board, or printed circuit board, defects such as delaminations or voids in epoxy may contain trapped gas. Under sufficient electric field stress and temperature conditions, electrical charge can accumulate in the vicinity or in the void. In the presence of a sufficient local electrical field, the gas can undergo ionizations enabling the discharge of local charge accumulation through the gas within the void. The resultant heating due to free electron and ion movement results in a rapid heating of the gas which then generates a high pressure pulse. This high pressure pulse is then transmitted as acoustic or mechanical energy through the surrounding dielectric structure. The acoustic sensors and transducers described herein are designed to detect and for the correct frequencies, and signal processing can be used to detect "partial discharges", "disruptive discharges", or "dielectric breakdown. " Surface partial discharges are also possible which may also produce acoustic energy that is transmitted into the dielectric structure, into conductors, interfaces as well as in the surrounding gas or liquid dielectric.

When a partial discharge occurs within an electrical device, the discharge may induce an acoustic vibration in the electrical device (or dielectric thereof), which may be detected and analyzes, as described herein. The vibration may generally resonate in a frequency range of approximately <NUM> to <NUM> (although other frequency ranges may occur as well).

<FIG> is a block diagram of an example system <NUM> for acoustically detecting dielectric breakdown of an electrical device <NUM>. System <NUM> includes an electrical device <NUM> and a controller <NUM>. Electrical device <NUM> includes a dielectric <NUM> and an electroacoustic (EA) transducer <NUM>. Controller <NUM> includes a memory <NUM> and a processor <NUM>.

In the example embodiment, dielectric <NUM> 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), a printed wiring board (PWB), rotating machinery windings or coils, and/or any other electric device or electric circuit.

Electrical device <NUM> may also include a plurality of components mounted on dielectric <NUM> and electrically connected by way of one or more electrical traces, wires, solder joints, and the like. The components included on electrical device are not generally central to an understanding of the present 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 variety of other hardware components.

In at least some embodiments, electrical device may 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. In addition, in at least some embodiments, electrical device <NUM> is installed in an aerospace system, such as an aircraft, and controls one or more systems or sub-systems of the aircraft or aerospace system.

EA transducer <NUM> is any of a variety of electroacoustic transducers, such as, for example, a contact microphone, a piezoelectric microphone or ceramic piezoelectric microphone, and/or any other EA transducer capable of mechanically coupling to electrical device <NUM> and/or dielectric <NUM> and detecting a structural acoustic vibration within electrical device <NUM> and/or dielectric <NUM>. In the example embodiment, EA transducer <NUM> is mechanically coupled to dielectric <NUM> or another portion of electrical device <NUM>.

In some embodiments, greater than a single EA transducer <NUM> may be mechanically coupled to dielectric <NUM>. For example, a plurality of EA transducers, each tuned to a specified frequency range, or each arranged to "listen to" a particular portion of dielectric <NUM>, may be implemented. In other embodiments, EA transducer <NUM> may include one or more air microphones (which are sensitive to vibrations in the air, as opposed to structural vibrations).

In some embodiments, a single or multiple EA transducer(s) <NUM> may be mechanically coupled to dielectric <NUM> as a permanent component to a large assembly. For example, a single or a plurality of EA transducers <NUM>, each tuned to a specified frequency range, or each arranged to "listen to" a particular portion of dielectric <NUM>, may be implemented as part of the assembly. In a printed circuit board embodiment, discrete mounted EA transducer <NUM> and associated control and drive circuitry <NUM>, <NUM> and <NUM> may be a part of the completed printed circuit assembly. This enables "self-monitoring" for either failures or derogations during the service life the assembly, which also enables preventative or conditional based maintenance or replacement.

As described in greater detail herein, EA transducer <NUM> may be configured to detect an acoustic vibration in a specified frequency range and generate an output signal in response. In at least some embodiments, EA transducer <NUM> may be selected or configured to detect a structural acoustic vibration in a frequency range associated with dielectric or electrical breakdown of dielectric <NUM>. For example, as described above, an acoustic vibration caused by dielectric breakdown or a partial electrical discharge (PD) within dielectric <NUM> may generally resonate in a frequency range of approximately <NUM> to <NUM> (although other frequency ranges may be accommodated). As a result, EA transducer may be configured to detect an acoustic vibration in these high-kHz to low-MHz ranges.

In response to detecting an acoustic vibration, EA transducer <NUM> may generate an output signal, which may include data (e.g., frequency data) indicating that a PD has occurred. In some cases include an amplifier or pre-amplifier may be connected to EA transducer <NUM> to amplify the signal output by EA transducer <NUM>. Likewise, in some embodiments, a filter, such as a band pass filter, may be connected to EA transducer <NUM> to exclude frequencies that are not associated with PD.

<FIG> is a circuit diagram of another example system <NUM> for acoustically detecting dielectric breakdown and/or partial discharge of electrical device <NUM>. System <NUM> is similar to system <NUM>, and includes the parts of system <NUM> described above. System <NUM> also includes a quadrilateral detection circuit <NUM>. Quadrilateral detection circuit <NUM> may be a Schering Bridge (or a modified version of a Schering Bridge), a Wheatstone Bridge, and/or another similar circuit.

Quadrilateral detection circuit <NUM> may thus include a first leg <NUM>, a second leg <NUM>, a third leg <NUM>, and a fourth leg <NUM>. Electrical characteristics of three of the four legs (e.g., legs <NUM>-<NUM>) may be known. For example, legs <NUM>-<NUM> may include one or more capacitors, resistors, and/or inductors, whereby a resistance, inductance, and/or capacitance of legs <NUM>-<NUM> may be known. Electrical circuit <NUM> may be included or connected in fourth leg <NUM>.

It will thus be appreciated that one or more electrical characteristics of electrical circuit <NUM> may be derived using the known values associated with first through third legs <NUM>-<NUM> and by solving for the electrical characteristics of electrical circuit using one or more known voltage and current equations (e.g., Kirchoff's laws). For example, data collected from quadrilateral detection circuit <NUM> may include a voltage across electrical circuit <NUM> (V<NUM>), a differential voltage (Vd) between third leg <NUM> and fourth leg <NUM> (i.e., electrical circuit <NUM>), and a current (i<NUM>-<NUM>) passing through electrical circuit <NUM>.

In operation, system <NUM> and/or system <NUM> may be used to test electrical device <NUM> for PD (or dielectric breakdown). For example, systems <NUM> or <NUM> may be used to perform real-time health monitoring of electrical circuit <NUM>. In another embodiment, systems <NUM> or <NUM> may be used to test electrical circuit <NUM> in a laboratory, such as, for example, in the instance that electrical circuit <NUM> is removed from the field for testing and analysis.

<FIG> is a flowchart illustrating an example process <NUM> for acoustically detecting PD and/or dielectric breakdown of electrical device <NUM>. In the example embodiment, controller <NUM> receives a data signal from EA transducer <NUM> (step <NUM>). The data signal may include frequency data representative of acoustic vibrations, if any, detected by EA transducer <NUM>. For example, in the event that PD occurs, the data signal may include an amplitude spike in the frequency range of dielectric breakdown (see additional description below).

In response to receiving the data signal, controller <NUM> may analyze the data signal (step <NUM>). For example, controller <NUM> may analyze the data signal to determine whether a frequency spike exits or has occurred in the frequency range of dielectric breakdown and/or partial discharge (step <NUM>). If such a frequency spike exists, controller <NUM> may determine that dielectric breakdown and/or partial discharge has occurred (or may have occurred), and generate an alert so indicating (step <NUM>). The alert may be provided to a user, such as, for example, on a computer display or as an audible or another type of alert. On the other hand, if the data signal does not include a frequency spike representative of PD or dielectric breakdown, controller <NUM> may continue to monitor electrical device <NUM> in real-time or substantially real-time, receiving continuing reports from EA transducer in the time domain (returning to step <NUM>).

Further, in some embodiments, one or more circuit characteristics of electrical circuit <NUM> may be measured and/or calculated by controller <NUM> using quadrilateral detection circuit <NUM>. Specifically, as described above, any of a voltage across electrical circuit <NUM> (V<NUM>), a differential voltage (Vd) between third leg <NUM> and fourth leg <NUM> (i.e., electrical circuit <NUM>), and a current (i<NUM>-<NUM>) passing through electrical circuit <NUM> may be determined. These data may be used to independent determine whether PD or dielectric breakdown have occurred, or they may be used in conjunction with the data signal received from EA transducer <NUM> to validate the data received from EA transducer. For instance, if the data signal received from EA transducer <NUM> includes a frequency spike, as described above, data from quadrilateral detection circuit may be used to validate that the data spike was caused by PD within electrical device <NUM>.

<FIG> is a graph <NUM> of several output waveforms of the system <NUM> (shown in <FIG>), in which no PD within electrical device <NUM> occurs. <FIG> is a graph <NUM> of the output waveforms of system <NUM>, in which PD of occurs. More particularly, graphs <NUM> and <NUM> show the voltage across electrical circuit <NUM> (V<NUM>), the differential voltage (Vd) between third leg <NUM> and fourth leg <NUM> (i.e., electrical circuit <NUM>), the current (i<NUM>-<NUM>) passing through electrical circuit <NUM>, and the data signal (VEA) received from EA transducer <NUM>. In <FIG> and <FIG>, V<NUM> has been reduced from an actual value by a factor of <NUM>; this is because a high voltage probe having a voltage divider was used to measure V<NUM> in these figures.

To evaluate the data shown in graphs <NUM> and <NUM>, controller <NUM> may, as described, above, and in one embodiment, determine whether data signal, VEA, includes frequency spike in the frequency range of dielectric breakdown and/or partial discharge. Such a frequency spike <NUM> is shown with reference to <FIG>. The data signal received from EA transducer <NUM> does not include a frequency spike (such as frequency spike <NUM>) in graph <NUM> of <FIG> (indicating that PD has not occurred). In at least some embodiments, a frequency spike in the range of dielectric breakdown and/or partial discharge indicated on data signal VEA may be sufficient to conclude that electrical circuit <NUM> has experienced some sort of dielectric breakdown and/or partial discharge.

In another embodiment, controller <NUM> may verify whether PD or dielectric breakdown have occurred based upon the data received or collected from quadrilateral detection circuit <NUM>. For example, controller <NUM> may determine the voltage, V<NUM>, across electrical circuit <NUM> at which frequency spike <NUM> occurs from graph <NUM>. In this example, V<NUM> at frequency spike <NUM> is approximately <NUM> Vrms. Controller <NUM> may, in addition, retrieve a thickness of dielectric <NUM> from memory <NUM>, and based upon an assumed shaped of a void or cavity within dielectric <NUM>, calculate an electric field, E, in the void or cavity giving rise to the PD. Specifically, controller <NUM> may calculate the electric field from the equation: <MAT>. In this equation, E is the electric field in the void, e is a relative permittivity of the dielectric, and Eo is the electric field in the dielectric.

In the equation above, assuming a dielectric thickness of <NUM>, Evoid may be calculated to equal approximately <NUM> x <NUM><NUM>V/m.

Using the calculated electric field in the void, Evoid, as shown above, controller <NUM> may further determine an estimated void radius using the following equation: <MAT>.

In the equation above, a is the estimated void radius, and P is the air pressure within the void in Pascal. Accordingly, controller may substitute the calculated electric field in the void, Evoid, and an estimated or measured air pressure within the void, P, to solve for a, the estimated void radius.

In this example, the void radius, a, calculated from the data received from quadrilateral detection circuit <NUM> is <NUM>.

Once a void radius, a, is calculated from the data collected from quadrilateral detection circuit <NUM>, the void radius, a, may be verified by calculating or estimating a duration or period of frequency spike <NUM> and dividing the period of frequency spike <NUM> by a speed of sound stored in memory <NUM>. For example, if memory <NUM> stores a speed of sound of <NUM>/s, and a period of frequency spike <NUM> is <NUM> ns, controller <NUM> may calculate an estimated void radius, b, of <NUM>.

Controller <NUM> may compare the estimated void radius, a, derived from quadrilateral detection circuit <NUM> to the estimated void radius, b, derived from the data signal received from EA transducer <NUM>, and if the two estimates are within a certain percentage tolerance of one another, controller <NUM> may conclude (or verify), as here, that frequency spike <NUM> in fact represents a partial discharge within electrical device <NUM>. The partial discharge may, in turn, result from an electrical discharge through ionized gas within a void of about <NUM>-<NUM> in radius.

<FIG> is a zoomed-in graph <NUM> of the output waveforms shown in <FIG>. Generally, <FIG> illustrates, in closer detail, frequency spike <NUM> and an accelerating pressure wave resulting from the partial discharge. Accordingly, <FIG> shows the voltage across electrical circuit <NUM> (V<NUM>), the differential voltage (Vd) between third leg <NUM> and fourth leg <NUM> (i.e., electrical circuit <NUM>), the current (i<NUM>-<NUM>) passing through electrical circuit <NUM>, and the data signal (VEA) received from EA transducer <NUM>.

At this scale, controller <NUM> may perform a third verification that PD has occurred within dielectric <NUM> of electrical device <NUM>. Specifically, as shown, if frequency spike <NUM> occurs at time, t<NUM>, the acoustic vibration within dielectric <NUM> (or within the air contained in the void, if an air microphone is used) oscillates to a second peak <NUM> at time, t<NUM>, to a third peak <NUM> at time, t<NUM>, and a fourth peak <NUM> at time, t<NUM>.

As a result of the fact that PD releases heat energy within dielectric <NUM>, a first time gap, A, between frequency spike <NUM> and a first subsequent peak 602may be measured. Likewise a second time gap, B, between peak <NUM> and a second subsequent peak 604may be measured, and a third time gap C between peak <NUM> and a third subsequent peak <NUM> may be measured. Generally, the time gap between an earlier occurring peak and a later occurring peak may be expected to decrease as the speed of sound within dielectric <NUM> increases in proportion to the resultant temperature increase (i.e., warmer transmission media may in at least some cases be expected to conduct acoustic vibrations at higher speeds).

Thus, to verify that frequency spike <NUM> was in fact the result of partial discharge, controller <NUM> may also compare a time gap between frequency spike <NUM> and a subsequent peak <NUM>, such as time gap A, to a time gap between peak <NUM> and peak <NUM> (i.e., time gap B) and/or peak <NUM> and peak <NUM> (i.e., time gap C). If time gap B and/or time gap C is less than time gap A, controller <NUM> may determine (or verify) that frequency spike <NUM> arose as a result of PD. A similar comparison of time gap C to time gap B may also be performed.

As described more briefly above, some embodiments may include a plurality of EA transducers <NUM>. A plurality of EA transducers <NUM> may be included for a variety of reasons. For example, in one embodiment, each EA transducer <NUM> of the plurality of EA transducers <NUM> may be positioned on a structure to detect or "listen for" PD in a region or zone proximate the EA transducer <NUM>. In a related embodiment, a plurality of EA transducers <NUM> may be positioned on a dielectric structure for the purpose of pinpointing a location of PD on the dielectric structure. For example, it will be appreciated that if three EA transducers <NUM> are positioned on a dielectric structure, a pinpoint location of PD on the dielectric structure may be geometrically determined (e.g., by triangulating or trilaterating) based upon a time of acoustic onset at each EA transducer <NUM> (i.e., a time that each EA transducer <NUM> detects the acoustic vibration).

Technical effects of the systems and methods for acoustically detecting dielectric breakdown and/or partial discharge of an electrical device include: (a) acoustic detection, using an electroacoustic transducer coupled to a dielectric of an electrical device, of an acoustic vibration representative of partial discharge and/or dielectric breakdown; (b) detection, using a quadrilateral detection circuit, of one or more circuit characteristics representative of partial discharge and/or dielectric breakdown; (c) verification, using the circuit characteristics derived from the quadrilateral detection circuit, of partial discharge and/or dielectric breakdown; (d) verification of partial discharge and/or dielectric breakdown based upon comparison of peak-to-peak distances or gaps between frequency spikes of peaks of a signal received from the electroacoustic transducer; and (e) generation of an alert, warning, or other indication that partial discharge and/or dielectric breakdown have occurred.

The systems and methods described herein are not limited to the specific embodiments described herein, but rather, components of the systems and/or steps of the methods may be utilized independently and separately from other components and/or steps described herein.

Although specific features of various embodiments of the disclosure may be shown in some drawings and not in others, this is for convenience only. 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.

As used herein, an element or step recited in the singular and proceeded with the word "a" or "an" should be understood as not excluding plural elements or steps unless such exclusion is explicitly recited. Furthermore, references to "one embodiment" of the present disclosure or "an example embodiment" are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.

Claim 1:
A system for acoustically detecting dielectric breakdown or partial discharge of an electrical device (<NUM>), the system comprising:
at least one electroacoustic, EA, transducer (<NUM>) configured to detect an acoustic vibration of the electrical device;
a controller (<NUM>) electrically connected to the at least one EA transducer (<NUM>), and
a quadrilateral detection circuit (<NUM>) having four legs, wherein three (<NUM>, <NUM>, <NUM>) of the four legs have a known resistance, and wherein the fourth leg (<NUM>) includes the electrical device, and wherein the quadrilateral detection circuit is electrically connected to the controller;
wherein the controller (<NUM>) 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;
determine, based upon the analyzing, whether the signal received from the at least one EA transducer includes data associated with an acoustic vibration in a frequency range of partial discharge of the electrical device;
receive at least one measurement from the quadrilateral detection circuit, wherein the measurement is any of a voltage across the electrical device (<NUM>), a differential voltage (Vd) between third leg (<NUM>) and fourth leg (<NUM>) and a current (I<NUM>-<NUM>) passing through the electrical circuit (<NUM>); and
in response to determining that the signal received from the at least one EA transducer includes the data associated with the acoustic vibration in the frequency range of partial discharge, verify the determination based upon the at least one measurement received from the quadrilateral detection circuit; and
generate an alert in response to determining that the signal received from the at least one EA transducer includes the data associated with the acoustic vibration in the frequency range of partial discharge.