Space charge phenomena on low-density poly ethylene film breakdown under heavy water absorption

The effect of dry and heavy water absorption on the electrical breakdown of low-density poly ethylene film was investigated. The temperature rise of the sample was observed by thermograph until the electrical breakdown using    direct current ramp voltage. The conduction current of low-density poly ethylene film was also measured, and the result was then correlated with thermograph measurement. Meanwhile, the space charge distribution in asample was measured by the pulse electro-acoustic method. From the thermograph, the result can be seen that under the heavy water absorption, the sample was more dissipated than the dry condition. Then, the breakdown occurs at the lower value of the voltage application, but the higher conduction current. Furthermore, the pulse electric acoustic show that increases the charge injection to the sample in the heavy water absorption. Increased space charges associated with an increase in the current conduction and the formation of heating, which results in a thermal breakdown

Rogowski coil sensor in the digitization process to detect partial discharge

This paper presents the construction of a Rogowski Coil sensor with an air core to detect partial discharge using a digital oscilloscope. Two types of sensors are used. The first is the primary sensor winding with back wire, and the second is without back wire, labeled BW and WBW, respectively. The numbers of primary-turn in the sensors are 5, 10, 20, and 40 turns. The performance of the sensors is tested using two types of tests. First, the wave response test with a fixed imitation partial discharge magnitude input is used to select the optimum sensitivity with the lower sampling rate, aims to select the peak or valley value as a magnitude partial discharge value. The second test is using an imitation partial discharge ramp to check the linearity of the sensors. The imitation of the partial discharge inputs is generated by a commercial charge calibrator. The wave response test results show an increase in the number of turns that corresponds to an increase of the sensor output for both sensors in a non-linear trend. In determining the sampling rate, the detection of magnitude in the valley is better than the peak. All sensors act linear toward the imitation partial discharge ramp either in BW or WBW conditions

The Enhancement of 3 MHz Ultrasonic Echo Signal for Conversion Curve Development for Acoustic Impedance Estimation by Using Wavelet Transform

Ultrasonic technology has already been used for many applications. Most of them are mainly used for object measurement. Some techniques have been widely applied to particular measurement by utilizing a very specific component. In this research, the previous technique to develop a conversion curve to obtain the acoustic impedance of the target is adopted. Then, we propose a 3 MHz concave shaped ultrasonic transducer for measuring liquids and a confirmation is needed to confirm if the system used is correct. Therefore, several saline solutions which property has been known are used. A low voltage of 10 Volt pulse is used to trigger the transducer. The ultrasonic wave is then transmitted through the multilayered mediums, which is pure water, clear acrylic, and the target. The echo from the interface between the acrylic and the target is then received by the same transducer. Some parameters such as peak and RMS are used to develop the conversion curve. A peak detection and comparison between the original echo and the processed one by using Wavelet transform (UWT and DWT) is then performed. Some analysis of the echo signal by using multiresolution and time-frequency analysis is also proposed. The result obtained from the measurement is then compared to that from the theoretical calculation. Based on the result, in terms of developing the calibration graph, only the RMS value (UWT) which has the closest trend to the result of the calculation, with the mean percentage error of 0.65512%, which is the smallest value among all parameters

ジツウンテン ジョウキョウ ヲ モギシタ オンド ジョウケン ニ オケル アツニク XLPE ゼツエン ケーブル ノ クウカン デンカ ソクテイ

This paper reports the space charge measurement results under actual operation temperature condition for a 23-mm-thick AC XLPE cable. A pulsed electro-acoustic (PEA) method which is newly proposed to measure the space charge characteristics of thick insulation samples accurately was applied. The AC XLPE cable was employed to observe the space charge accumulation clearly. The changes in space charge and electric field distributions corresponding to the changes in temperature and voltage were observed. As a result, we found that the space charge distribution under the heat cycle condition shows complex behavior as the temperature distribution changing. We concluded that it is important to measure space charge characteristics under heat cycle conditions in addition to the conventional space charge measurement under constant temperature conditions to understand the space charge characteristics of the full-size XLPE cable

Sulfide Catabolism Ameliorates Hypoxic Brain Injury

The mammalian brain is highly vulnerable to oxygen deprivation, yet the mechanism underlying the brain’s sensitivity to hypoxia is incompletely understood. Hypoxia induces accumulation of hydrogen sulfide, a gas that inhibits mitochondrial respiration. Here, we show that, in mice, rats, and naturally hypoxia-tolerant ground squirrels, the sensitivity of the brain to hypoxia is inversely related to the levels of sulfide:quinone oxidoreductase (SQOR) and the capacity to catabolize sulfide. Silencing SQOR increased the sensitivity of the brain to hypoxia, whereas neuron-specific SQOR expression prevented hypoxia-induced sulfide accumulation, bioenergetic failure, and ischemic brain injury. Excluding SQOR from mitochondria increased sensitivity to hypoxia not only in the brain but also in heart and liver. Pharmacological scavenging of sulfide maintained mitochondrial respiration in hypoxic neurons and made mice resistant to hypoxia. These results illuminate the critical role of sulfide catabolism in energy homeostasis during hypoxia and identify a therapeutic target for ischemic brain injury