研究者詳細 - 小島　寛樹

論文 - 小島　寛樹

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Simulation on Discharge Inception Voltage Improvement of GIS Spacer with Permittivity Graded Materials (epsilon-FGM) Using Flexible Mixture Casting Method 査読有り国際誌

N. Hayakawa, Y. Miyaji, H. Kojima, K. Kato

IEEE Transactions on Dielectrics and Electrical Insulation 25 巻 ( 4 ) 頁： 1318 - 1323 2018年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEEE

For electric field grading in GIS spacers, the application of functionally graded materials (FGM) with spatial distribution of dielectric permittivity (ϵ) can be one effective solution. In this paper, we propose the flexible mixture casting (FMC) method as a novel and practical technique to fabricate ϵ-FGM for GIS spacers. We verified that the relative permittivity (er) can be controlled from ϵr = 4 to ϵr = 30 by varying the loading ratio of high permittivity filler particles under the FMC method. Toward the practical application of ϵ-FGM, we verified the relaxation effect of maximum electric field strength and the improvement effect of discharge inception voltage in SF6 gas in a simplified GIS spacer model using ϵ-FGM under the FMC method. Simulation results revealed that the maximum electric field strength can be effectively reduced and the discharge inception voltage can be significantly improved compared with using a constant and uniform permittivity.

DOI： 10.1109/TDEI.2018.007236

Volume Effect of Dynamic Breakdown Strength in LN₂ for Insulation Design of Resistive Superconducting Fault Current Limiters 査読有り国際誌

N. Hayakawa, K. Ishida, M. Mimbu, H. Kojima, S. Isojima, M. Kuwata

IEEE Transactions on Applied Superconductivity 28 巻 ( 4 ) 頁： 5600804 2018年6月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEEE

Toward the practical and rational insulation design of a resistive superconducting fault current limiter, it is necessary to consider the electrical breakdown (BD) due to the transient bubble generation in liquid nitrogen (LN2) at the quench of the HTS materials. We have been investigating the intrinsic BD characteristics of LN2 without bubbles and the dynamic BD characteristics of LN2 under transient bubble disturbance, respectively. In this paper, we have investigated the dynamic BD characteristics of LN2 for different electrode diameters and gap lengths, and have discussed in terms of the volume effect of dynamic BD strength.

DOI： 10.1109/TASC.2018.2799308

Fault Current Limitation Coordination in Electric Power Grid With Superconducting Fault Current Limiters 査読有り国際誌

N. Hayakawa, Y. Maeno, H. Kojima

IEEE Transactions on Applied Superconductivity 28 巻 ( 4 ) 頁： 5602304 2018年6月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEEE

This paper proposes the concept of 'fault current limitation coordination' in a future electric power grid with multiple superconducting fault current limiters (SFCL). Not only the fault current limitation of each SFCL on a transmission line, but also the transient stability of the grid with SFCLs should be taken into account, because the disturbance is brought about in the grid by the sudden appearance and disappearance of a large impedance of SFCL at the fault current limitation and recovery after the fault clearance, respectively. In this paper, both of the fault current limitation of SFCLs and the internal phase angle oscillation of generators were calculated by PSCAD/EMTDC to evaluate the operational feasibility or coordination of SFCLs in a 275/77-kV transmission system model.

DOI： 10.1109/TASC.2018.2818279

誘電率傾斜機能材料(ε-FGM)を用いたGISスペーサモデルの作製とSF₆ガス中絶縁破壊電圧の理論的推定査読有り

宮路仁崇，小島寛樹，加藤克巳，早川直樹

電気学会論文誌Ａ（基礎・材料・共通部門誌） 138 巻 ( 4 ) 頁： 155 - 162 2018年4月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：一般社団法人電気学会

For the relaxation and optimization of electric field distribution around Gas insulated switchgear (GIS) spacers, the application of functionally graded materials (FGM) with spatial distribution of dielectric permittivity (ϵ) can be one of the effective solutions. In this paper, we fabricated the coaxial disk-type ϵ-FGM using SrTiO3/SiO2 particles by the centrifugal force method. We also proposed the coaxial cone-type ϵ-FGM by the flexible mixture casting method and evaluated its electric field reduction effect and breakdown voltage in SF6 gas by the volume-time theory.

DOI： 10.1541/ieejfms.138.155

Improvement Mechanism of AC Breakdown Voltage of Insulating Oil with Dispersed Nanoparticles 招待有り国際誌

H. Kojima, T. Kondo, M. Hanai, N. Hayakawa

Electronics and Communications in Japan 100 巻 ( 12 ) 頁： 69 - 75 2017年12月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Wiley Periodicals, Inc.

We investigated the fundamental insulation characteristics of insulating oil with dispersed nanoparticles. The AC breakdown voltage of the insulating oil increased by mixing the dispersed hydrophilic nanoparticles, because the hydrophilic nanoparticles absorbed moisture in the oil, which decreased the number of weak points in the oil for breakdown. In contrast, the hydrophobic nanoparticles did not contribute to the increase of AC breakdown voltage, and decreased the AC breakdown voltage. On the other hand, in the case of overdosing of nanoparticles, the aggregation of nanoparticles caused the decrease in the AC breakdown voltage of the oil, which depended upon the volume concentration of nanoparticles regardless of the diameter of nanoparticles. The aggregation of nanoparticles was led by dielectrophoresis phenomenon, which brought the gap length dependence of the AC breakdown voltage of the insulating oil with the dispersed nanoparticles, because the gradient of electric field strength at the gap was smaller in the case of shorter gap length.

DOI： 10.1002/ecj.12016

Discharge Pattern Discrimination in Vacuum Interrupter with Non-contact Measurement of Shield Potential 査読有り国際誌

F. Kong, H. Kojima, N. Hayakawa, T. Kimura, M. Tsukima

IEEE Transactions on Dielectrics and Electrical Insulation 24 巻 ( 5 ) 頁： 3265 - 3269 2017年10月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEEE

Vacuum interrupter has a composite insulation system. When an internal insulation fails, the discharge has complex and various patterns. Previously, based on the discharge development characteristics, we proposed a discrimination method for the discharge pattern in vacuum interrupter. We measured the applied voltage, anode current, and shield potential waveforms, respectively. From the analysis of the measured waveforms, we can estimate the discharge patterns and discharge path lengths. In this paper, a non-contact shield potential measurement was proposed when the shield potential cannot be measured directly. Furthermore, verification tests with this measurement method were conducted and the effectiveness of the discrimination method was confirmed.

DOI： 10.1109/TDEI.2017.006512

Optimum Breakdown Charge for Maximum Dielectric Strength in Spark Conditioning in Vacuum under a Non-uniform Electric Field 査読有り国際誌

H. Kojima, T. Takahashi, N. Hayakawa, K. Hasegawa, M. Sakaki

IEEE Transactions on Dielectrics and Electrical Insulation 24 巻 ( 4 ) 頁： 2660 - 2665 2017年8月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEEE

Spark conditioning is an effective method of increasing the dielectric strength in vacuum. In this paper, we determined the breakdown (BD) charge dependence for spark conditioning in vacuum under various non-uniform electric fields and with different anode materials. We discuss the BD mechanism in terms of BD arising from anode heating or cathode heating. Experimental results revealed that for anode heating BD, the longer the gap distance, the larger the BD charge needed to obtain maximum dielectric strength. In contrast, for cathode heating BD, the BD charge for maximum dielectric strength was smaller than that for anode heating BD. From these results, we estimated the optimal BD charge to maximize the 50% BD electric field strength, i.e. the dielectric strength, for spark conditioning in vacuum.

DOI： 10.1109/TDEI.2017.006462

Discharge Pattern Discrimination for Composite Insulation System in Vacuum 招待有り国際誌

F. Kong, H. Kojima, T. Kimura, M. Tsukima, N. Hayakawa

Electrical Engineering in Japan 200 巻 ( 3 ) 頁： 3 - 12 2017年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Wiley Periodicals, Inc.

In order to develop higher-voltage vacuum circuit breakers (VCBs), the investigation of discharge phenomenon in vacuum is necessary. In vacuum interrupters (VIs) with composite insulation systems, the discharge has complex and various patterns at the internal insulation failures. In this paper, based on the discharge development characteristics, we propose a discrimination method for the discharge pattern in vacuum. We measured the applied voltage, anode current, and shield potential waveforms, respectively. From the feature of the measured waveforms, we classified the discharge patterns. Furthermore, based on the relation between discharge development time and discharge path length, we estimated the discharge patterns and discharge path lengths. In addition, we conducted a verification experiment of the discrimination method using a VI model. Experimental results revealed that the estimated discharge patterns and discharge path lengths were consistent with the observed discharge ones and the effectiveness of the discrimination method was confirmed.

DOI： 10.1002/eej.22982

Breakdown Characteristics and Mechanisms of Liquid Nitrogen under Transient Thermal Stress for Superconducting Fault Current Limiters 査読有り国際誌

N. Hayakawa, T. Matsuoka, H. Kojima, S. Isojima, M. Kuwata

IEEE Transactions on Applied Superconductivity 27 巻 ( 4 ) 頁： 7700305 - 7700305 2017年6月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEEE

We have been investigating the electrical breakdown (BD) characteristics of liquid nitrogen (LN2) with a transient thermal stresses to simulate the quench conditions of resistive-type superconducting fault current limiters (SFCL). We call such BD of LN2 with the transient thermal stress as 'dynamic BD,' and discriminate it from that with a continuous thermal stress. In this paper, we investigated the dynamic BD characteristics of LN2 for different LN2 pressures, electrode sizes, and terms of transient thermal stress input. In addition, we obtained the BD characteristics of LN2 with the continuous thermal stress, and compared them with the dynamic BD characteristics. Furthermore, we analyzed the statistical scattering of the time from the thermal stress input to the dynamic BD occurrence and discussed the dynamic BD mechanisms of LN2. We also proposed a flowchart of rational and reliable electrical insulation design of resistive-type SFCL based on the dynamic BD characteristics of LN2.

DOI： 10.1109/TASC.2017.2651115

Electrical Insulation Characteristics and Mechanisms of Low Dielectric Loss Materials for High-Voltage HTS Cables 査読有り国際誌

N. Hayakawa, K. Ishida, T. Matsuoka, H. Kojima

IEEE Transactions on Applied Superconductivity 27 巻 ( 4 ) 頁： 4800904 - 4800904 2017年6月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEEE

Toward the practical development of high-voltage high-temperature superconducting (HTS) cables, high electrical insulation characteristics, and low dielectric loss become important. Dielectric loss drastically increases with the increase of operation voltage of HTS cables. Therefore, it is highly expected to find a novel insulating material with low dielectric loss for the high-voltage HTS cables. We have focused on Tyvek {^{\circledR}}, polyethylene (PE) nonwoven fabric, and Tyvek {^{\circledR}}/PE, a syntactic paper bonding PE-sheet on Tyvek{^{\circledR}} by heat, as low dielectric loss materials. In this paper, we investigated fundamental partial discharge inception characteristics and their mechanisms of Tyvek{^{\circledR}} immersed in liquid nitrogen (LN2).In addition, we compared the electrical insulation characteristics of Tyvek{^{\circledR}}, Tyvek {^{\circledR}}/PE, and polypropylene laminated paper (PPLP{^{\circledR}}), and discussed their mechanisms.

DOI： 10.1109/TASC.2016.2645796

Calculation Model for Predicting Partial-discharge Inception Voltage in a Non-uniform Air Gap while Considering the Effect of Humidity 査読有り国際誌

T. Rokunohe, T. Kato, H. Kojima, N. Hayakawa, H. Okubo

IEEE Transactions on Dielectrics and Electrical Insulation 24 巻 ( 2 ) 頁： 1123 - 1130 2017年4月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEEE

A calculation model for predicting the inception of partial discharge (PD) in a non-uniform air gap on the basis of theories of electron avalanche and streamer phenomena is proposed. "Partial discharge inception voltages" (PDIVs), under an assumed absolute humidity of less than 20g/cm3, calculated using the proposed model were compared with experimentally measured ones and found to be almost equivalent. Furthermore, the relationship between negative ions and humidity was incorporated into the calculation model, and it was confirmed that the calculated and measured PDIVs tend to be the roughly the same under a wide humidity range under various gap length between electrodes. The proposed partial-discharge inception model based on theories mentioned above was therefore judged to be effective for predicting changes in PDIV when humidity changes.

DOI： 10.1109/TDEI.2017.005920

ナノ粒子添加による絶縁油の交流絶縁破壊電圧向上メカニズム査読有り

小島寛樹，近藤貴文，花井正広，早川直樹

電気学会論文誌Ａ（基礎・材料・共通部門誌） 137 巻 ( 2 ) 頁： 101 - 106 2017年2月

担当区分：筆頭著者,　責任著者記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：一般社団法人電気学会

We investigated the fundamental insulation characteristics of insulating oil with dispersed nanoparticles. The AC breakdown voltage of the insulating oil increased by mixing the dispersed hydrophilic nanoparticles, because the hydrophilic nanoparticles absorbed moisture in the oil, which decreased the number of weak points in the oil for breakdown. In contrast, the hydrophobic nanoparticles did not contribute to the increase of AC breakdown voltage, and decreased the AC breakdown voltage. On the other hand, in the case of overdosing of nanoparticles, the aggregation of nanoparticles caused the decrease in the AC breakdown voltage of the oil, which depended upon the volume concentration of nanoparticles regardless of the diameter of nanoparticles. The aggregation of nanoparticles was led by dielectrophoresis phenomenon, which brought the gap length dependence of the AC breakdown voltage of the insulating oil with the dispersed nanoparticles, because the gradient of electric field strength at the gap was smaller in the case of shorter gap length.

DOI： 10.1541/ieejfms.137.101

Reduction Method of Fluctuation in Partial Discharge Inception Voltage for Inverter-Fed Rectangular Wire Motors 招待有り国際誌

T. Wakimoto, H. Kojima, N. Hayakawa

Electrical Engineering in Japan 198 巻 ( 2 ) 頁： 3 - 10 2017年1月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Wiley Periodicals, Inc.

We investigated the decisive factors that affect partial discharge inception voltage (PDIV) fluctuation between the coil wires under a sinusoidal voltage by using a rectangular wire motor. As a result, we found that PDIV under low humidity fluctuates by the surface charge, and PDIV under high humidity varies transitionally with the surface conductivity activated by predischarge. From these analyses, we proposed the measurement method of PDIV with a low fluctuation and transition for the rectangular wire motors, which will be optimized by environmental humidity, predischarge condition, and measuring frequency.

DOI： 10.1002/eej.22908

Measurement and Evaluation of Partial Discharge Inception Voltage for Enameled Rectangular Wires under AC Voltage 査読有り国際誌

T. Wakimoto, H. Kojima, N. Hayakawa

IEEE Transactions on Dielectrics and Electrical Insulation 23 巻 ( 6 ) 頁： 3566 - 3574 2016年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEEE

Recently, the market for EVs (Electric vehicles) and HEVs (Hybrid electric vehicles) has been expanding. In these vehicles, rectangular wires have started to be used for the traction motor coil to increase the motor performance. As a result, the insulation techniques become important because the applied voltage between the wires is increasing due to a change in the motor structure and the increase in the driving voltage. In order to safeguard the motor insulation, partial discharge (PD) between coil wires must be controlled, and to do this, the coil wires should be coated with an insulator of a suitable thickness. For this purpose, the PD measurement technique is important in design and inspection on the manufacturing lines. However, the PD measurement between wires is unstable, and is especially affected by the measurement method and environmental factors. In this paper, we clarify the factors as well as the mechanism affecting the PD inception voltage (PDIV) between enameled rectangular wires under AC voltage. The effects of the ambient humidity, the pre-discharge conditions and the measuring frequency on the PDIV were analyzed. As a result, it was confirmed that when there was pre-discharge in a high humidity environment, the PDIV displayed fluctuating characteristics in which it momentarily decreased and then increased. We observed the discharges and analyzed the electric field distribution. The results showed that in high humidity environment, pre-discharge causes moisture contained in the air to adhere to the coating surfaces, resulting in an increase in the surface conductivity, which influences the electric field strength in the air gap between coil wires. These analyses indicated that the PDIV can be measured stably and reliably at high frequencies in a high humidity environment.

DOI： 10.1109/TDEI.2016.005645

Dependence of Spark Conditioning on Breakdown Charge and Electrode Material under a Non-Uniform Electric Field in Vacuum 査読有り国際誌

H. Kojima, T. Takahashi, N. Hayakawa, K. Hasegawa, H. Saito, M. Sakaki

IEEE Transactions on Dielectrics and Electrical Insulation 23 巻 ( 5 ) 頁： 3224 - 3230 2016年10月

担当区分：筆頭著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEEE

Spark conditioning is an effective method for improving dielectric strength in vacuum. In this paper, we discuss the dependence of spark conditioning on breakdown (BD) charge and electrode material in vacuum under various non-uniform electric field and circuit parameters. We applied a negative impulse voltage to a rod-plane electrode configuration with a cathode made of stainless steel (SS), Cu-Cr, or OFHC Cu (Cu), and an anode made of SS or Cu. We changed the gap distance, the tip radius of the rod electrode and the circuit parameters. As a result, the conditioning effect, i.e. improving BD electric field strength by the conditioning, depended on the BD charge (QBD) and reached its maximum value against QBD. The optimal QBD required to achieve the maximum conditioning effect decreased with the cathode melting point. Moreover, when BD caused by cathode heating (CH-BD) occurred readily, with the SS anode, the BD electric field strength at the cathode surface after conditioning depended on QBD, regardless of the gap distance and the tip radius. Thus, for CH-BD, we estimated the withstand voltage that could be achieved by spark conditioning from the electrode configuration and QBD. However, when BD caused by anode heating (AH-BD) occurred easily with the Cu anode, the optimal QBD was larger than that for CH-BD because the cathode temperature was lower for AH-BD than for CH-BD.

DOI： 10.1109/TDEI.2016.7736889

真空中の複合絶縁系における放電パターンの識別査読有り

孔飛，小島寛樹，木村俊則，月間満，早川直樹

電気学会論文誌A（基礎・材料・共通部門誌） 136 巻 ( 9 ) 頁： 594 - 602 2016年9月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：一般社団法人電気学会

In order to develop higher-voltage vacuum circuit breakers (VCB), the investigation of discharge phenomenon in vacuum is necessary. In vacuum interrupters (VI) with composite insulation systems, the discharge has complex and various patterns at the internal insulation failures. In this paper, based on the discharge development characteristics, we propose a discrimination method for the discharge pattern in vacuum. We measured the applied voltage, anode current, and shield potential waveforms, respectively. From the feature of the measured waveforms, we classified the discharge patterns. Furthermore, based on the relation between discharge development time and discharge path length, we estimated the discharge patterns and discharge path lengths. In addition, we conducted a verification experiment of the discrimination method using a VI model. Experimental results revealed that the estimated discharge patterns and discharge path lengths were consistent with the observed discharge ones and the effectiveness of the discrimination method was confirmed.

DOI： 10.1541/ieejfms.136.594

Discharge Characteristics for Various Discharge Patterns under Negative Lightning Impulse Voltage in Vacuum 査読有り国際誌

F. Kong, Y. Nakano, H. Kojima, N. Hayakawa, T. Kimura, M. Tsukima

IEEE Transactions on Dielectrics and Electrical Insulation 23 巻 ( 2 ) 頁： 813 - 816 2016年4月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEEE

In order to develop higher voltage vacuum interrupters (VIs), electrical insulation performances in vacuum should be improved. The discharge in VI has various and complex patterns, such as breakdown in vacuum gap and surface flashover on a solid insulator. In this paper, we investigated three discharge patterns: the discharge in vacuum gap, the discharge in vacuum gap via shield, and the surface flashover on solid insulator, respectively. By measuring shield potential and insulator surface potential, we analyzed the discharge characteristics for various patterns, and clarified the relevant discharge development process. We found that the breakdown development process in vacuum gap depends on the gap length and the surface flashover development process on a solid insulator depends on the applied voltage and surface distance.

DOI： 10.1109/TDEI.2015.005388

Discharge Characteristics of Composite Insulation System with Floating Electrode and Solid Insulator in Vacuum 査読有り国際誌

F. Kong, Y. Nakano, H. Kojima, N. Hayakawa, T. Kimura, M. Tsukima

IEEE Transactions on Dielectrics and Electrical Insulation 23 巻 ( 2 ) 頁： 1219 - 1225 2016年4月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEEE

For the development of vacuum interrupters for their higher voltage application in power transmission systems, it is necessary to clarify the discharge characteristics of composite insulation systems with a shield (floating electrode) and a solid insulator in vacuum. In this paper, we focus on the composite discharge patterns via the shield and the solid insulator. For cathode-shield-insulator-anode (c-s-i-a) and cathode-insulator-shield-anode (c-i-s-a) electrode configurations, the discharge can be classified into two independent processes: breakdown in vacuum gap and surface flashover on the solid insulator. Furthermore, we have found that the breakdown development time increases with the increase in the gap length and the surface flashover development time depends on the voltage peak after flashover inception, which are consistent with discharge development characteristics for individual gap breakdown and surface flashover, respectively. These results are significant to understanding and discriminating the composite discharge patterns and discharge path in vacuum interrupters.

DOI： 10.1109/TDEI.2015.005588

Pressure Dependence and Size Effect of LN₂ Breakdown Characteristics Under Transient Thermal Stress 査読有り国際誌

N. Hayakawa, T. Matsuoka, K. Ishida, H. Kojima, S. Isojima, M. Kuwata

IEEE Transactions on Applied Superconductivity 26 巻 ( 3 ) 頁： 7700604 2016年4月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：IEEE

Electrical insulation of liquid nitrogen (LN2) for a high-temperature superconducting (HTS) power apparatus can be categorized into two breakdown (BD) modes. One is the intrinsic or conventional BD of LN2. The other is the BD of LN2 with transient bubbles, such as a quench. In this paper, the BD characteristics of LN2 with transient bubbles were investigated for different LN2 pressures and electrode diameters. Experimental results revealed that the BD strength of LN2 with transient bubbles was lower than the intrinsic BD strength of LN2. The difference between the intrinsic BD strength and the BD strength with transient bubbles in LN2 became smaller with the increase in the LN2 pressure and electrode diameter. Furthermore, the BD characteristics of LN2 with continuous bubbles were investigated and compared with the BD characteristics of LN2 with transient bubbles. As a result, the insulation design of an HTS power apparatus in consideration of their quench condition will be rationalized than the design based on the continuous thermal stress.

DOI： 10.1109/TASC.2016.2532469

真空中沿面フラッシオーバ進展過程における絶縁物上過渡帯電存在時の実効的2次電子放出係数査読有り

中野裕介，小島寛樹，土屋賢治，早川直樹

電気学会論文誌A（基礎・材料・共通部門誌） 136 巻 ( 3 ) 頁： 128 - 134 2016年3月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：一般社団法人電気学会

Based on the mechanism of surface flashover development in vacuum, we have investigated that the surface flashover can be suppressed by the increase in electric field perpendicular to the insulator surface. In this study, we clarified the suppression conditions of surface flashover in terms of the transient surface charge and the effective secondary electron emission coefficient along the insulator surface.

DOI： 10.1541/ieejfms.136.128

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