Description:“A PARTIAL DISCHARGE MEASUREMENT DEVICE FOR HIGH VOLTAGE SUBSTATION EQUIPMENT”

FIELD OF INVENTION

This invention is directed to a partial discharge measurement device for high voltage substation equipment.

BACKGROUND OF INVENTION:

Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.

The steep increase in the demand for electric power necessitates the introduction of higher capacity power equipment with increased voltage rating. The reliability of such equipment is very important, as an unplanned outage of any equipment causes a heavy replacement cost, in addition to the loss due to power shut down. From the reliability point of view, insulation design of equipment is considered as a key factor. It must be adequate to withstand the electrical stress during normal service and also under abnormal conditions viz., system faults. Insulation systems of HV equipment, however perfect in its initial state, inevitably degrade in service. Extreme environmental conditions and the presence of a high electric stress, act to impair the integrity of the dielectric system. At some stage, partial discharges begin to increase inside the insulation, providing additional erosive aging to the insulation. The magnitude, number and distribution of the partial discharge pulses can identify predominant aging mechanisms. Changes in these quantities, as a function of equipment age, become a measure of cumulative insulation deterioration.

Partial discharges can occur due to the improper design, manufacturing and also due to the various service conditions. There are many types of partial discharges (PD) that can occur in the insulation. Although the insulation can function with such discharges within, but it may deteriorate in course of time. The rate of failure depends upon the magnitude and the frequency of discharges. Partial discharge detection and measurement in HV equipment after manufacturing and during service is therefore very important in order to predict the severity with which the insulation system is functioning.

Traditionally, Partial Discharge measurement is carried out widely using capacitive coupling method at test labs and at shop floor after manufacturing of a high voltage equipment. This method is in accordance with IEC 61270 standard, and is also called the conventional PD measurement method. This method requires a noise- free test setup, and a coupling capacitor to decouple and measure the PD pulses. The coupling capacitor should be of the same or higher voltage rating, as the test object. To test different type of test objects viz. transformer, motors, gas insulated switchgear etc. different type of coupling capacitors are needed. It is seen that for PD testing of different high voltage equipment, different PD test setup/coupling devices/connections are necessary. A comprehensive PD testing solution which can be used to measure PD in all HV equipment, having different ratings (from HV to UHV class) is not available. Because of this reason, product or equipment specific PD test setups are normally needed. Hence a need is always there to find a technique/solution which can be effectively used to measure PD in any HV equipment, both at routine testing stage as well as for continuous online monitoring, after installation at site. The invented UPDMS, as described in this patent, provides the required solution.

PRIOR ART OF INVENTION:

Various innovations and patents cover the different techniques and technologies of partial discharge measurements. These techniques are based on conventional IEC61270 standard and use coupling capacitor based, acoustic based or UHF based PD sensing and evaluation. Also, most of the patents cover the signal processing aspects for accurate PD measurements.

Reference may be made to following patents:

Patent (ref US8669773) mentions a method and devices for calibrating a partial discharge measuring device and for locating faults on cables. The patented method helps to re-calibrate the measuring device continuously during the measurement, and to determine the fault location with great precision. Patent (ref US 20120077444) describes a device and method for improved detection and analysis of partial discharge activity in and around a high voltage electrical equipment. The invention relates in general to adaptive detection and discrimination of low repetition rate broadband impulsive emissions.

Patent (ref WO2005121821) relates to a method and device for determining location of partial discharge in a transformer or a reactor, in which signal produced by PD are detected and supplied to an evaluation device. The invention provides a device and method that makes possible straightforward, rapid and accurate location of partial discharges in a transformer. Patent (ref US006255808) invention relates to a device for measuring partial discharges in gas-insulated high voltage facilities, having a first calibratable sensor suitable for measurement in the HF range and a second sensor suitable for detecting signal components characteristic of partial discharges, in particular for measurement in the UHF range.

As mentioned above, mostly all the inventions patented are either related to PD measurements in specific HV equipment like transformer, reactor, gas-insulated switchgear, cable etc. or is related to PD signal processing and detection. The invention is related to a general purpose or universal PD sensing technique as described in this innovation, which is not covered in any of the above referred patents.

OBJECTS OF INVENTION

Primary object of the invention is to provide a Partial Discharge Measurement device for high voltage substation equipment.

Another object of the invention is to provide a PD sensing device and its coupling arrangement, for connection to any HV equipment for PD measurement.

Still another object of the invention is to provide a Partial Discharge Measurement device, which can undertake PD calibration as per requirement of the IEC 61270 standard.

Yet another object of the invention is to provide a Partial Discharge Measurement device catering to different HV equipment both for offline and online PD monitoring.

These and other objects and advantages of the present invention will be apparent to those skilled in the art after a consideration of the following detailed description taken in conjunction with the accompanying drawings in which a preferred form of the present invention is illustrated.

SUMMARY OF THE INVENTION

One or more drawbacks of conventional systems and process are overcome, and additional advantages are provided through the apparatus/composition and a method as claimed in the present disclosure. Additional features and advantages are realized through the technicalities of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered to be part of the claimed disclosure.

The present invention caters to the development of a Novel Universal Partial Discharge Measurement Solution (UPDMS), for high voltage substation equipment. The broad summary of the invention is:

-Conceptualization and finalization of a method to develop a PD measurement solution for HV equipment which can universally be used, irrespective of the type and rating of equipment;

-Development of a universal PD sensing solution which broadly comprises of a PD sensing unit also called the inductive PD sensor, a PD coupler for connecting/installing the sensor to the test object and the associated processing unit;

-A novel method of calibrating the UPDMS in-accordance with IEC requirement;

-Experimental validation of the invented UPDMS capability to measure PD in different equipment and its performance evaluation vis-à-vis the established conventional PD measurement technique;

-Establishing a ratio factor to correlate the PD charge magnitude measured by UPDMS with the charge magnitude measured by PD sensing technique;

-Establishing a multiplication factor to correlate the milli volt (mV) level output of inductive inductive PD sensor [1] with the charge magnitude (pC) measured by PD sensing technique;

-A novel universal PD sensing method catering to different HV equipment irrespective of the type and rating of equipment.
Various objects, features, aspects, and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.

It is to be understood that the aspects and embodiments of the disclosure described above may be used in any combination with each other. Several of the aspects and embodiments may be combined to form a further embodiment of the disclosure.

The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:

The illustrated embodiments of the subject matter will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout. The following description is intended only by way of example, and simply illustrates certain selected embodiments of devices, systems, and processes that are consistent with the subject matter as claimed herein, wherein:-

Figure 1 shows: Universal PD sensing method catering to different HV equipment

Figure 2 shows: An inductive PD coupler cum sensing device for universal PD sensing.

Figure 3 shows: Process for calibrating the inductive PD coupler cum sensing device in accordance with IEC standards, for reliable measurements.

Figure 4 shows: Characterization and Comparison of PD level using the developed universal PD measurement method Vs. Conventional PD measurement method

The figures depict embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.

DETAIL DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS:

While the embodiments of the disclosure are subject to various modifications and alternative forms, specific embodiment thereof have been shown by way of example in the figures and will be described below. It should be understood, however, that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternative falling within the scope of the disclosure.
The present invention makes a disclosure regarding a technology pertaining to a partial discharge measurement device for high voltage substation equipment
Partial Discharge is a small electrical high frequency current discharge, occurring inside an insulating material of a high voltage equipment. The PD discharge basically occurs due to certain defects viz. voids, metallic / non-metallic particles etc. inside insulation. These defects may result to degradation of insulation over a period of time. To know the PD value, the generated discharge pulses need to be measured and quantified. A novel technique as shown in Figure 1 is invented to measure PD in any high voltage equipment. The Test object of the Figure 1 can be any HV equipment viz. Power Transformer, Instrument Transformer, Switchgear, Motor, Cable, Bushing, Insulator etc. For measuring the PD, the test object is subjected to high voltage at its HV terminal, using a test transformer. The value of this high voltage is in-accordance with the rating of the test object and the test voltage value as specified in the relevant IEC standard. The ground terminal of the test object is connected to the earth/ground, through the invented Inductive PD coupler. The PD coupler output, which is the measure of PD level inside the test object insulation, is provided to a PD processing unit. The PD processing unit determines the PD magnitude and other PD parameters in accordance with the IEC requirements. In the present invention, the PD is thus measured by installing/connecting the developed Inductive PD coupler at the ground connection of the HV equipment (test object). Since all HV equipments are required to be grounded during high voltage testing as well as while operating at site, the invented solution can be used for PD measurement in any HV equipment, under all conditions i.e. during testing after manufacturing at manufacturing works or at site for continuous online PD monitoring.

Now, reference may be made to Figure 2 illustrating the construction details of the developed inductive PD coupler cum sensing device, for PD sensing in any HV equipment. The PD sensing part of this device is the Inductive PD Sensor [1] which has been designed to sense the PD signal from the ground/leakage current of a test object. The Inductive PD Sensor [1] is made up of a special magnetic core material, having a defined number of copper wire windings, called the secondary windings or turns. The used special magnetic core material senses only the high frequency PD pulses, from the leakage current and rejects the power frequency (50Hz) current magnitude. For undertaking PD measurement, the inductive PD coupler is connected to the ground/earth terminal of the test object, using the Connection to Test Object (A) end of the coupler. The other end of the coupler depicted as Connection to Earth/Ground (B) is grounded i.e. connected to the earth. The two ends of the coupler viz. Connection to Test Object (A) and Connection to Earth/Ground (B) are shorted using the conducting rod (2). This arrangement helps to keep the test object grounded under HV testing or under operating condition at site, which is a mandatory requirement. Also this arrangement simultaneously ensures to position the Inductive PD Sensor [1], around the leakage current carrying conducting rod (2), for sensing the PD signal for measurement. To isolate the conducting rod (2) from the metallic casing [5] of the coupler, an insulating material [3] is provided at both ends of the PD coupler. The casing [5] is typically made of aluminum and protects the inductive PD sensor [1]. The sensed PD signal is brought out of the PD coupler, using the Output Signal (4) port. The Output Signal (4) port is connected to the PD processing unit for quantifying the PD magnitude. The Output Signal (4) port is designed using special connector which ensures noise-free transfer of PD signal to the PD processing unit.

The Output Signal (4) port is designed using special connector which ensures noise-free transfer of PD signal to the PD processing unit.

A process for calibrating the universal PD sensing setup is in accordance with IEC standards, for reliable PD measurements.

Characterization of different PD parameters is conducted by using the developed universal PD sensing module.

A method of determining the Ratio Factor is established which relates the charge (pC) magnitudes of the universal PD sensing technique to the conventional PD measurement method. This Ratio Factor can also be made close to 1 (one) depending on sensitivity requirements of PD measurement of a power equipment.

The design parameters including magnetic core material, number of copper wire windings, called the secondary windings or turns etc. are provided to achieve required Ratio Factor.

The developed inductive PD sensor [1] provides equivalent mill volt (mV) signal directly at its output, which corresponds to the PD signal i.e. pC charge magnitude. For the designed PD sensor module, there is a fixed multiplication factor relationship between PD level (pC charge magnitude) and the mV level, at the output of inductive PD sensor [1]. This multiplication factor is established through calibration of inductive PD sensor [1] by using a standard charge calibrator module.

Figure 3 shows the process for calibrating the inductive PD coupler cum sensing device setup, in accordance with IEC requirement, for reliable measurements. Calibrating the PD measurement test setup, before undertaking actual measurements, is a necessary requirement as per standard. A novel method to implement this calibration process is developed for the UPDMS, which uses the inductive PD coupler. A standard charge calibrator module, capable of generating known PD charge magnitude ranging from 5pC to 100pC, is used as reference PD source to inject known PD pulses through the developed PD coupler. To initiate the calibration, the charge calibrator output is connected to the Connection to Test Object (A) terminal of the PD coupler and the other end of the charge calibrator is connected to the Connection to Earth/Ground (B) terminal of the coupler. The Output Signal (4) port of the PD coupler is in-turn connected to the PD processing unit to display the sensed PD magnitude by the coupler. To start with the calibration process, PD signal of approx. 50pC is injected through the PD coupler, using the charge calibrator. The PD processing unit displays the sensed PD magnitude. If the displayed value is not 50pC, then the gain/sensitivity of the processing unit is varied, so that 50pC is displayed by it. Once this is achieved the charge calibrator output is changed to other PD values, ranging from 5pC to 100pC for verifying the correct calibration of the PD test setup. Once it is ensured that the value injected by the charge calibrator is also displayed by the PD processing unit for different values of injected PD pulses, the calibration of the test setup is correctly achieved.

Referring to Figure 4 showing the characterization of PD level, using the developed UPDMS and its comparison with the results achieved using the conventional capacitive coupling based PD measurement method. This characterization and comparison was undertaken to verify and validate the developed UPDMS. To undertake this PD characterization and comparison, different HV equipments (test objects) were used like bushing, insulator, stator-bar, cable etc. The test results and the graphs for different test objects, showed the similar pattern and behavior. The graph depicted in Figure 4 is the result achieved while undertaking the comparative study on a 11 kV defective (cracked) bushing sample (test object). Defective sample was intentionally chosen so that we can observe sufficient PD activity, on application of high voltages. Figure 4 shows the comparison of the applied voltage vs. the generated PD (charge) pattern/graph, measured using the invented UPDMS as well as the conventional method. It is seen that with the increase in applied voltage, the Partial Discharges (Charge magnitude) increases. This is depicted in both the conventional technique as well as the UPDMS. It is also seen that the charge magnitude (pC) measured by UPDMS is smaller as compared to conventional method for the same applied voltage. The variation of Voltage with respect to Charge (pC) shows the same pattern for both methods. Further, it was seen that with the increase in applied voltage the No. of PD events (pulses) increases, while using both the methods. The variation of Voltage with number of PD events shows the same pattern for both the methods. In addition to above, with the increase in applied voltage the Quadratic Discharge Rate also increases. This is also depicted in both the PD detection methods. Overall, it is observed that for all the measurements undertaken, the PD parameters as recorded by the UPDMS and the conventional method shows the similar pattern. This is highly desirable, as by analyzing these patterns one can predict the type of defect in the insulation as well as its location. Further there is clear relationship between the observed PD Charge value (pC) measured using the conventional method and the invented UPDMS. This relationship can be quantified and is referred to as Ratio Factor for the invented UPDMS. This Ratio Factor would help in computing the equivalent PD charge value (pC) based on conventional (IEC based) detection techniques, from the computed PD charge value (pC), measured by UPDMS. It is seen from the experiments that the Ratio Factor for the PD Charge (pC) parameter for the invented UPDMS is approx. 9 (Nine). Thus by multiplying the PD charge (pC) magnitude measured using the UPDMS, with this ratio factor of 9 (nine), one can compute the actual PD charge value, which one would have observed if the conventional i.e. IEC standard PD detection method would have been used. Here it is worth mentioning that this Ratio Factor for computing the PD charge value using the developed UPDMS, which comprises of invented PD sensor [1] along with the PD processing unit, was approximately same for different test objects/HV equipment. The Ratio Factor is designed based on sensitivity requirement of PD measurement of a power equipment. Based on the requirement of Ratio Factor, inductive PD sensor [1] is designed. The design parameters like magnetic core material, number of copper wire windings, called the secondary windings or turns etc. are considered to achieve required Ratio Factor. It is also possible to measure and quantify equivalent mill volt (mV) signal directly at the output of inductive PD sensor [1], which corresponds to the PD signal i.e. pC charge magnitude. For the designed PD sensor module, there is a fixed multiplication factor relationship between PD level (pC charge magnitude) and the mV level, at the output of inductive PD sensor [1]. This multiplication factor is established through calibration of inductive PD sensor[1] by using a standard charge calibrator module. The charge calibrator module is the one which can generate known PD charge magnitudes, ranging from 5pC to 100pC. This calibrator is used as reference PD source to inject known PD pulses through the developed inductive PD sensor [1]. For calibration and deducing the relationship between PD level (pC charge magnitude) and the mV level, the charge calibrator output is connected to the Connection to Test Object (A) terminal of the PD coupler and the other end of the charge calibrator is connected to the Connection to Earth/Ground (B) terminal of the coupler. Overall as shown in Figure 4, the PD parameter patterns as sensed by both conventional method and the UPDMS shows the same trend. Further, the ratio factor can be made close to 1 (one) by designing inductive PD sensor accordingly. As the PD parameter trend information is necessary to monitor the healthiness of the insulation over a period of time, the UPDMS PD trend information would enable continuous online PD monitoring of the insulation condition. Hence, it can be clearly inferred that the invented UPDMS provides a novel solution to measure as well as online monitor PD in any HV equipment, of any rating.

Application:

Partial Discharge (PD) measurements in high voltage (HV) equipment is used to determine the healthiness of its insulation after manufacturing, as well as during service. Partial Discharge (PD) is the discharge which occurs inside the HV insulation and leads to its slow deterioration, over a period of time. IEC standard for different HV equipment specifies standard limit of PD magnitude in pico-coulombs (pC). In other words, any HV equipment after manufacturing is being tested for the PD value, which should be within the specified limits as per IEC standard. Also, during service the PD values are monitored using different online methods, for checking the healthiness of the equipments insulation over its life-span. It may be noted that for undertaking PD measurements in different HV equipment like switchgear, transformers, motors, cables etc., various techniques/methods and sensing devices are required. Also, for online PD measurements in these equipments at site, different sensors are used. The innovation which is described here-with, provides a novel PD sensing solution which can be used for all HV equipment both for offline and online PD measurements. Thus, this invention provides a universal PD sensing solution for all HV equipment.

Advantages of Invention

The advantage of the developed UPDMS is that, unlike other method of PD measurement which are test equipment specific and require a complex test setup, the invented UPDMS can be used for PD measurement of any test equipment with simple test arrangement and can cater to both offline as well as online PD measurement.

Working of Invention

The invented UPDMS has been successfully employed for PD measurement of different equipment’s. Measurement of PD, both at shop floor as well as at site has been undertaken using the developed system/process.

Test Result

The developed PD measurement solution is very simple and cost-effective as compared to the conventional PD measurement methods. Just by installing the developed inductive PD coupler at ground/earth connection of the test object PD can be measured. It has been experimentally and practically seen that the PD values measured using the developed system as matching the PD values measured using the conventional IEC based capacitive coupling method.

Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references below to the "invention" may in some cases refer to certain specific embodiments only. In other cases, it will be recognized that references to the "invention" will refer to subject matter recited in one or more, but not necessarily all, of the claims.

Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all groups used in the appended claims.
It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particulars claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogues to “at least one of A, B and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B”.

The above description does not provide specific details of manufacture or design of the various components. Those of skill in the art are familiar with such details, and unless departures from those techniques are set out, techniques, known, related art or later developed designs and materials should be employed. Those in the art are capable of choosing suitable manufacturing and design details.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. It will be appreciated that several of the above-disclosed and other features and functions, or alternatives thereof, may be combined into other systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may subsequently be made by those skilled in the art without departing from the scope of the present disclosure as encompassed by the following claims.

The claims, as originally presented and as they may be amended, encompass variations, alternatives, modifications, improvements, equivalents, and substantial equivalents of the embodiments and teachings disclosed herein, including those that are presently unforeseen or unappreciated, and that, for example, may arise from applicants/patentees and others.

While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.
, Claims:We Claim:

1. A Partial Discharge Measurement device for high voltage substation equipment comprises a Partial Discharge (PD) sensing unit constituting inductive Partial Discharge (PD) sensor (1), a Partial Discharge (PD) coupler for connecting/installing the sensor (1) to the test object and the associated processing unit, wherein the inductive PD coupler is connected to the ground/earth terminal of the test object, using the Connection to the Test Object (A) end of the coupler and the other end of the coupler Connection to Earth/Ground (B) is grounded i.e. connected to the earth, in which the two ends of the coupler viz. Connection to Test Object (A) and Connection to Earth/Ground (B) are shorted by conducting rod (2);wherein
the conducting rod (2) is isolated from metallic casing [5] of the coupler by providing an insulating material [3] at both ends of the PD coupler and Output Signal (4) port is connected to the PD processing unit for quantifying the PD magnitude.

2. The Partial Discharge Measurement device as claimed in claim 1, wherein the Inductive PD Sensor [1] senses the PD signal from the ground/leakage current of the test object, in which the Inductive PD Sensor [1] is made up of a magnetic core material, having a defined number of copper wire windings forming the secondary windings / turns, wherein the magnetic core material senses the high frequency PD pulses, from the leakage current and rejects the power frequency current magnitude.

3. The Partial Discharge Measurement device as claimed in claim 1 or 2, wherein the casing [5] is made of material including Aluminum and protects the inductive PD sensor [1], in which the sensed PD signal is brought out of the PD coupler by the Output Signal (4) port.
4. The Partial Discharge Measurement device as claimed in claims 1-3, wherein the Output Signal (4) port is connected to the PD processing unit for quantifying the PD magnitude.