Pattanadech, Norasage

Preferred name

Alternative Name

Pattanadech, N.

Main Affiliation

School of Engineering

norasage.pa@kmitl.ac.th

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Generalized regression networks for partial discharge classification
(2016-01-18)
Pattanadech, N.
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Nimsanong, P.
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Potivejkul, S.
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Yuthagowith, P.
;
Polmai, S.
This document represents a partial discharge (PD) classification by using Generalized Regression Networks (GRNN) model. Two PD classification models, GRNN1 with 11 input variables and GRNN2 with 3 selected derived statistic parameters, were investigated for classification of PD signals into 5 patterns, corona at high voltage side in air, corona at low voltage side in air, corona at high voltage side in mineral oil, corona at low voltage side in mineral oil and surface discharge in mineral oil. The conventional PD measurement was performed for measuring PD signals of the artificial PD models. The statistical parameters of the PD signals such as skewness, kurtosis, asymmetry, cross correlation and so on were calculated from the developed computer program. Then, 60% of the experimented data was used as a training data for the developed PD classification models. Another 40% experimented data was used to evaluate the performance of the designed PD classification models. It was found that the GRNN1 model can classify PD patterns better than GRNN2 model. The accuracy for PD classification of GRNN1 model was 100% while the accuracy of GRNN2 model was 97.5% of 40 testing data.
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The Dissipation Factor (tan δ) Monitoring of A Stator Winding Insulation of A Synchronous Machine
(2018-11-14)
Phloymuk, N.
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Nimsanong, P.
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Phumipunepon, N.
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Potivejkul, S.
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Wiangtong, T.
the aim of this paper is to describe the dielectric loss tangent (tan δ) behaviors of the stator winding insulation of the 14.5 MVA 11kV synchronous machine from 2014-2017. This machine is still operated up to now. The tan δ values at different test voltages was measured and recorded. It was found that the sharp increase in tan δ values gave the sign of a significant degree of contamination and damage on the insulation surface which was proved by inspection. From the investigation the tan δ measurements is one of the effective ways to monitor and evaluate the insulation conditions of the stator insulation. The analysis and discussion of the existed problem of the synchronous machine are also included in this paper.
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Condition assessment of MV motor based on charge difference and charge ratio analysis
(2019-07-01)
Nimsanong, P.
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Boonsaner, N.
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Pattanadech, N.
Insulation resistance and polarization index tests have been conducted in utility companies as one of the major tools for evaluating the integrity of stator winding insulation of medium voltage motor. Unfortunately, the information obtained from the measurement results are the combination of the electrical problem and polarization problem in the insulation system not separated from each other. This paper presents a new approach so-called charge difference analysis (QDA) and charge ratio analysis (QRA) to identify the problem in stator winding insulation occurred from conduction mechanism or/and polarization mechanism. Moreover, proposed parameters which are QD, QG and QR have been conducted on field motors in the following case studies: The first group (A) consists of two motors of which one is new motor and the other one is severely aged motor, the second group (B) consists of two motors of which one is lightly loaded motor and the other one is thermally aged motor, and the third group (C) consists of a single motor, on which PDC measurements have been carried out after maintenance in 2014 and 2016 respectively. From experiments, it was found that proposed parameters are able to provide useful information about the condition of stator insulation, i.e. contamination or/and degradation.
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Studies of Electrical and Thermal Characteristics of Natural Ester Immersed Transformer Compared with Mineral Oil Immersed and Palm Oil Immersed Transformer
(2018-11-14)
Maneerot, S.
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Jariyanurat, K.
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Nimsanong, P.
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Bunlaksananusor, C.
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Kunakorn, A.
This paper represents studies of electrical and thermal characteristics of natural ester immersed transformer compared with mineral oil immersed and palm oil immersed transformer by designing and constructing three single-phase transformers with rated 400/1000V 10kVA, the first transformer used mineral oil, the second transformer used natural ester, and the last one used palm oil, for studying about electrical properties, thermal properties and chemical properties under different types of liquid insulation in each transformer. First of all, three types of liquid insulation were tested with many item such as dielectric breakdown strength according to IEC 60156, dielectric dissipation factor following to ASTM D924-99. Besides, dielectric breakdown strength of impregnated pressboard were also investigated following to IEC 60243-1. Moreover, the chemical properties of the insulations were tested for some properties such as moisture content in accordance with ASTM D1533-00, interfacial tension according to ASTM D0971-99, acidity according to ASTM D974-02. After that, transformers were operated at 100 % of designed rated with inductor load for four months by which the temperature, current, and voltage were recorded every hour. Every two months, the liquid insulation was sampling from each transformer to be investigated. From the test results, they can concluded that natural ester are the alternative liquid insulation for using instead of mineral oil. In part of palm oil, it has good properties but it has the weak points about dielectric dissipation factor and acidity which are higher than the others.
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Frequency dependence parameter analysis of underground cables with and without joint
(2018-06-29)
Nimsanong, P.
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Kunakorn, A.
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Pattanadech, N.
This paper represents the dielectric investigation of XLPE power cables with and without cable joint (premolded joint) by using polarization and depolarization current (PDC) measurement. To investigate the polarization phenomena of the underground cable (case 1) and the underground cable with the premolded joint (case 2), the XLPE cables with the cross-section area of 240 mm2 and 5 m long with rate voltage of 12/20(24) kV with and without premolded joint were used in the experiment. In this research work, the DC voltage of 1,000V was applied to insulation system for measuring polarization current, i<inf>pol</inf>(t). Then, suddenly disconnected the DC applied voltage source to short circuit the tested cable to measure depolarization current, i<inf>dep</inf>(t), In case 1, the PDC measurement was only for 100 seconds due to its homogeneous insulation of XLPE cable; only conduction current and interfacial polarization current with short relaxation time existed. In case 2, the PDC measurement was done for 2,000 seconds. In this case the polarization current was from XLPE cable mentioned and the interfacial polarization current from the barrier between XLPE cable and cable joint. From the experiment, the frequency dependence of the complex capacitance and dielectric dissipation factor of the underground cable and the underground cable with the premolded joint were analyzed. It is found that the trend of real part of the complex capacitance and the conduction loss of both case studies is not much different. However, the trend of imaginary part of the complex capacitance and polarization loss of both case studies is clearly different. Two peaks of imaginary parts of complex capacitance and polarization loss of the underground cable with joint is from XLPE and the junction of XLPE and joint.
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Polarization and Depolarization Current Measurement of Underground Cable with Different Cable lengths, Temperatures and Test Voltages
(2018-11-14)
Thungsook, K.
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Nimsanong, P.
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Marukatut, N.
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Pattanadech, N.
This paper represents the polarization and depolarization current (PDC) measurement of 12/20(24) kV XLPE power cable with different cable lengths, cable dimensions, temperatures and test voltages. In experiment 1, the XLPE cable with 5 m long and cross section of 240 mm2 was prepared for (Case V1) investigation. Moreover, two of 2.5 m cables connected by the pre-molded joint (Case V2) was also prepared. In the experiment 1, the PDC experiment was investigated with different step DC test voltages i.e., 500V, 750V and 1,000V respectively. Besides, the dielectric response of underground cables with the length of 15 cm with cross section of 185 mm2 and the lengths of 2.5 m and 5 m with cross section of 240 mm2 including the length of 100 m with cross section of 70 mm2 were prepared for experiment 2. To investigate the effect of temperatures on dielectric response, the cable specimen with the length of 15 cm with cross section of 185 mm2 was set up under ambient temperatures of 30, 50, 70 and 90 degree Celsius for PDC measurement in experiment 3. PDC test results obtained from the experiments were compared. Then the dielectric parameters for PDC experiment such as charge difference analysis, capacitance ratio analysis, and polarization loss factor were analyzed and reported in this paper.
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Polarization and depolarization current measurement applied for investigation of underground cable system problems
(2019-07-01)
Pattanadech, N.
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Phongsirichairojna, T.
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Navapittayaratana, N.
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Nimsanong, P.
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Jirathipchaisakul, T.
This research investigates the problems in XLPE cables system. The 12/20(24) kV underground cable with the cross section area of 240 mm2 was used in the experiment. Two 3 meter long cables were connected by a cable joint where the defect was simulated on. The dielectric investigation of XLPE cable system by polarization and depolarization current (PDC) measurement was performed comparatively among four different cases: a healthy cable with healthy heat shrinkable joint (case1), a cable joint with an incision on XLPE surface (case2), a cable joint contaminated with 20 micron iron powder on XLPE surface (case3) and a cable joint contaminated with 20 micron copper powder on XLPE surface (case4). Diagnostic parameters, PDC shapes, dielectric dissipation factor (DDF) and conduction current, derived from PDC test results for analyzing the dielectric response are proposed in this paper.
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A fast and accurate dielectric response measurement for transformer moisture assessment and remaining life estimation
(2020-07-01)
Nimsanong, P.
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Maneerot, S.
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Pattanadech, N.
This paper proposes a fast dielectric response measurement for transformer moisture assessment and remaining life estimation. The dielectric response measurements in the time domain for in-service transformers with various insulation conditions categorized into four levels, i.e., excellent, good, fair, and poor conditions, were investigated. The dielectric response measurements were investigated by polarization and depolarization time for 100, 500, 1000, and 3000 seconds. For the dielectric response of oil-paper insulation of such a transformer, the conductivity of oil in ducts and moisture content in paper can be estimated by using the curve fitting technique in advanced evaluation tool in PDC-Analyzer-1MOD. Besides, significant parameters, i.e., dc resistance, insulation resistance, polarization index, tan δ of oil, complex capacitance, conductivity and interfacial polarization loss factors in the low-frequency range, the paper remaining life time, and bubbling inception temperature were evaluated with a single dielectric response measurement result. To confirm the PDC measurement test results, other insulation test techniques were performed. The dielectric response results obtained from PDC measurement were compared with the results from the other mentioned techniques. It was found that the polarization time for 3000 seconds and depolarization time for 500 seconds is suitable for assessing the moisture content in paper and other dielectric parameters comparatively.
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Partial discharge classification using probabilistic neural network model
(2016-01-18)
Pattanadech, N.
;
Nimsanong, P.
;
Potivejkul, S.
;
Yuthagowith, P.
;
Polmai, S.
The aim of this paper is to propose the probabilistic neural network (PNN) model for classification partial discharge (PD) patterns, which comprised of corona discharge at high voltage side and at low voltage side in air, corona discharge at high voltage side and at low voltage side in mineral oil and surface discharge in mineral oil. Partial discharge signals were investigated by conventional method according to IEC60270. Independent parameters such as skewness, kurtosis, asymmetry, and cross correlation of the Φ-q-n PD patterns were analyzed. The PNN PD classification model was constructed. Moreover, the principal component analysis (PCA) was utilized to reduce the input dimension of the developed PD classification model. After that, 60% of the experimented data was used as a training data for the PD classification models. Another 40% experimented data was used for evaluation the performance of the designed PD classification models. Effects of spread parameters and input neuron numbers on the PD classification performance were examined. It was found that the first four score variable was appropriate to be used to construct the designed PNN model with the optimal spread value of 1.2. The proposed PD classification model can classify PD types with the accuracy of 100% of 40 tested data.
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Dielectric properties of mineral oil compared with natural ester
(2017-11-29)
Jariyanurat, K.
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Nimsanong, P.
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Chaisiri, P.
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Maneerot, S.
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Kitcharoen, P.
In this paper, dielectric properties of the mineral oil, ELECTROL A, and the natural ester, FR3, are comparatively investigated. AC breakdown voltages, dielectric dissipation factor, relative permittivity, partial discharge inception voltage and partial discharge of the mineral oil and of the natural ester are tested. In order to verify the capability in practical use of the mineral oil and the natural ester for transformer insulation systems, the impregnation of such liquids with pressboard insulation is performed. The impregnated pressboards are tested in the laboratory to measure the AC breakdown voltages. It is found that the natural ester shows superior dielectric properties to the mineral oil except the dielectric dissipation factor.

Pattanadech, Norasage

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