Use of Plat-Bar Electrode Media to Detect Partial Discharge in Epoxy Resin Materials on PCB Surfaces

The electric power system must have a protection system with reliable electric power isolation, so that the supply of electrical energy works properly and optimally. There are several kinds of disturbances in the electric power distribution system, one of which is a partial discharge. This study aims to investigate the effect of plate-rod electrodes on partial discharge, partial discharge voltage limits in solid insulation, and the characteristics of partial discharge in electrode media, and waveforms in partial discharge detection sensors. After conducting research, it was found that in the plate-rod type electrode media, the PDIV voltage appeared earlier than the plate-plate electrode media due to the cross-sectional area of the electrode media. And the limit of the pre-discharge voltage of PCB type solid insulation on the plate-bar electrodes is at a voltage of 1.3 kV. Several indicators to determine the characteristics of the partial discharge are background noise off (BGN off), background noise on (BGN on), partial discharge inception voltage (PDIV), and partial discharge voltage. After being examined, the value of each partial discharge detection voltage was obtained at negative and positive polarity voltages on the electrode plates and plate needles respectively 2.85 kV, 2.95 kV and 1.32 kV, 1.57 kV.


Introduction
The electrical energy distribution system of course has a protection system, one of which is commonly called electric power isolation [1].For the supply of electrical energy from power plants to work properly and maximally, the system must also be well isolated.In general, the insulation system is divided into three types, namely solid, liquid and gas insulation [2].For the use of insulators in distribution and transmission systems have the type and electrical properties depending on the composition, thickness, surface conditions and temperature.If the applied voltage exceeds the insulation field strength limit, it will cause a breakdown voltage and the insulation will be damaged [3].The function of the insulation is to protect parts of the electric voltage from things that are not desirable.Insulation media, be it solid, liquid or gas, is required to have good quality [4].The non-uniformity of the electric field on the insulating medium/dielectric will cause the phenomenon of Partial Discharge, which will lead to the failure of the insulation itself [5].
Therefore, researchers will test how to detect partial discharge using plate-rod electrode media (other than needle-plate) on solid insulation.In addition, the researcher will look for the partial discharge characteristics of solid PCB FR4 (epoxy resin) insulation on the rod-plate electrode media to determine the average value of 10 trials and the standard deviation value to estimate the accuracy of the data taken.This partial discharge detection uses two detection sensors including an HFCT (High Frequency Current Transformer) sensor and a loop antenna which will later be seen comparing the frequency of the partial discharge voltage on the plate-rod electrode media.

Literature Review
Partial discharge is a local discharge of electricity that partially bridges the insulation between conductors and occurs both on the surface of the conductor and inside the conductor.Partial discharge measurement is a general standard that defines a broad line of partial discharge (PD) measurements in electrical equipment.This applies to partial discharge measurements using alternating voltage (AC) up to 400 Hz and direct voltage (DC) [6].Cavity discharge occurs because there are air bubbles (voids) in a dielectric material.Generally, gas insulation has much less strength than solid insulation.When a solid dielectric material is subjected to electrical pressure, the gas will carry a greater pressure than solid insulation [7].Surface Discharge occurs in the region that is directly related to the dielectric surface.The area is subjected to very high electrical pressure resulting in a partial discharge [8].And Corona discharge occurs due to the occurrence of ionization rate events under the pressure of an electric field.This ionization is caused by changes in the structure of neutral molecules or neutral atoms that occur due to collisions between neutral atoms and free electrons in the air [9].
Partial Discharge Measurement Parameters, Background Noise Off (BGN Off), The main purpose of off BGN measurement is to determine the noise condition when the measurement circuit is still in off mode.Background Noise On (BGN On), The BGN on measurement aims to determine the noise condition when the voltage source is turned on but is still at 0 kV [10].Partial Discharge Inception Voltage (PDIV) is the lowest voltage at which a partial discharge occurs in the test circuit when the test voltage is gradually increased from a lower value [11].
Epoxy resin is the most important type of hard resin used in high voltage insulation technology.Its chemical characteristics are epoxy group.

Figure 1. Chemical Characteristics of Epoxy Groups
Epoxy resin is very useful for industry and factories, because of its high mechanical strength, low mass density, good adhesion to materials and metals, and is widely used as an insulating material for electrical equipment because of its excellent electrical characteristics [12].
The distribution of surface discharge with a two-dimensional fluid model experiment, from the comparison between the discharge in the dielectric isolation area and the discharge in the filament, is obtained where the discharge in the dielectric area is two times greater than the discharge in the filament [13].These conditions indicate that the discharge on the dielectric insulation has a greater effect.Research related to the effect of surface morphology of dielectric materials on surface discharge that occurs in air media.The results of this test show that the discharge at atmospheric pressure dielectric produces three types of discharge, including the filament mode, homogeneous mode, and the mixed mode.The results show that in the homogeneous mode type with the ceramic test material, there is a minimal condition where vibration occurs when the discharge occurs in a homogeneous mode [14].

Research Methode
In a study requires a research flow to achieve the objectives of the research.The diagram can be seen in figure 2.

Figure 2. Research Flowchart
The research was carried out by studying the literature to find out the phenomena that occur in partial discharges that occur at partial discharges on the surface.Furthermore, the researchers determined the characteristic parameters of the partial surface discharge that occurs in dielectric materials.At the testing and data collection stage, it was carried out according to the IEC 60270 standard [6], then data processing was carried out to verify the tests that had been carried out.If the results of data analysis are declared valid then the data is carried out at the analysis stage to find out the phenomena that occur in PCB material testing, and if the data results are invalid then the research process is returned to the partial discharge characteristics parameter stage.From the results of the analysis, conclusions are drawn to determine the extent to which the results of the research were carried out to determine the occurrence of phenomena in testing PCB materials using the rod plate electrode test model.Step-Up Transformer

Data Collection Method
The work sequence for data collection in this research is shown in the flowchart in the following figure.

Figure 12. Data Collection Method
Following are the steps for measuring BGN off, BGN on, PDIV, and the partial discharge voltage on the PCB surface:

Experiment Preparation:
1. Perform grounding using a grounding stick at the output of the step-up transformer.
2. Create a series of experiments as shown Figure 13: 3. Turn on the high voltage source and oscilloscope.4. Make settings on the oscilloscope as follows: • First calibrate the oscilloscope • Setting channel 1 for the HFCT sensor and channel 2 for the loop antenna sensor.
• Go to the acquire menu then change the mode to peak detect.
• Go to the display menu then change the display to vector settings.
• Go to the trigger menu then set the coupling trigger to AC.

Effect of Stem-Plate Electrode Media on Partial Discharge Research
In previous research conducted [5], it was found that the research was carried out using homogeneous electrodes of the plate type with PCB type research media.It is known that in the PCB research media there are cavities or voids so that partial discharges can occur.As a follow-up study, the authors want to examine whether partial discharge can occur in a plate-bar type non-homogeneous field.After conducting research, researchers found several differences from previous studies.Are as follows: This can affect the PDIV voltage of each of these studies, so that it can be explained that in the platerod type electrode media, the PDIV voltage appears earlier than the plate-plate electrode media due to the cross-sectional area of the electrode media.

Characteristics of Partial Discharge Waves on the PCB insulation surface
To look for the characteristics of the partial discharge wave on the surface of the PCB using plate-bar electrode media, researchers took some data such as BGN off, BGN on, PDIV values, and also the PD voltage value, where the data will be processed and found the average value.along with its standard deviation.Following are the results of 10 partial discharge detection studies: From the research that has been done, the negative pre-discharge voltage or PDIV is obtained at a voltage of 1.3 kV, while the positive pre-discharge voltage or PDIV is obtained at a voltage of 1.5 kV.And from ten partial discharge experiments with each voltage variation on the two detection sensors using plate-stem electrode media, it was found that the average value of the study was higher than the standard deviation value of the study.This proves that partial discharge research on PCB (epoxy resin) insulating media with plate-bar electrodes has a high level of accuracy and has a minimum error value.The results obtained from the off and on background noise tests show that there is no significant interference with the place where the test is carried out.This is in terms of the results of the Loop Antenna and HFCT sensor measurements with a value of Vpp   The image above shows the partial discharge waveform obtained from each sensor.The yellow noise indicates the HFCT sensor, while the blue noise indicates the loop antenna sensor.From these waveforms, it is known that the HFCT sensor has better sensitivity than the loop antenna sensor.In addition, detailed wave value results from partial discharge detection using plate-bar electrode media are also obtained.From each of the pictures above, it is shown that the Vmax, Vmin, and Vpp values of the loop antenna sensor have a greater value than the HFCT sensor.It is known that the more sensitive the sensor from the partial discharge study is the smaller the frequency value on the sensor will be.

Conclusion
The results of the study were obtained where the use of Plat-Bar Electrode Media to Detect Partial Discharge on Epoxy Resin Materials on the PCB Surface Using the HFCT Sensor and Loop Antenna has the characteristics, Detection with the HFCT sensor obtained the initial positive and negative partial discharge voltages are 2.85 kV and 2, 95 kV.While the Loop Antenna Sensor initial positive and negative partial discharge voltages are 1.32 kV and 1.57 kV, respectively.From these results it can be concluded that the plate-bar electrode media detects partial discharge faster in solid insulation in the form of PCB (epoxy resin) compared to other electrode media because of the size and cross-sectional area of the positive pole of the electrode.the plate-bar is smaller than the negative pole of the plate-bar electrode.In this case, the other electrode media is the plate electrode media.
The PDIV value obtained in the partial discharge detection study using plate-bar type electrode media with PCB solid insulation (epoxy resin), was obtained first with a negative PDIV with a voltage value of 1.3 kV, while a positive PDIV was obtained at a voltage value of 1, 5 kV.And from ten partial discharge experiments with each voltage variation on the two detection sensors using plate-bar electrode media, it was found that the standard deviation value showed a small result so that it was more accurate with the average value.This proves that partial discharge research on PCB (epoxy resin) insulating media with plate-rod electrodes has a minimum error value and a high degree of accuracy.
The HFCT sensor has a higher level of sensitivity compared to the loop antenna sensor.On the other hand, the frequency voltage value of the loop antenna sensor is greater than that of the HFCT sensor.So that the frequency voltage value is inversely proportional to the sensitivity value on the sensor.

Figure 14 .Figure 18 .
Figure 14.BGN Off Figure 15.BGN On 8.21 mV and Vpp 1.89 mV on BGN Off, and Vpp 9.259 mV and Vpp 1.898 mV on BGN On.While the results of the PDIV test were read by the Loop Antenna and HFCT sensors at Vpp 18,927 mV and Vpp 8,617 mV on Negative PDIV, and Vpp 22,986 mV and Vpp 10,586 mV on Positive PDIV.The results of subsequent tests by increasing the PDIV test value 1.2x the PDIV voltage value show that, Negative PDIV does not have a significant increase in the voltage value for increasing the voltage source, whereas Positive PDIV has a significant effect where the Vpp value increases twice the initial PDIV voltage.

4. 3 .
HFCT Sensor Wave Value Results and Loop Antenna on Partial Discharge Detection using Plate-Stem Electrode Media Partial discharge detection research on plate-bar electrode media was carried out using electrical methods or by using sensors in the research.The sensors used in the partial discharge detection include the HFCT (High Frequency Current Transformer) sensor and the loop antenna sensor.The following are the results of the research displayed by the oscilloscope:

Figure 20 .
Figure 20.Partial Discharge Waves from Each Sensor

Figure 21 .
Figure 21.Frequency Voltage at One Partial Discharge Voltage on HFCT Figure 22.Frequency Voltage at One Partial Discharge Voltage on Loop Antenna

Table 1 .
PDIV Voltage Results on Different Electrode Media.