Tree Initiation In Polyethylene Research Articles

Concoction Component Analysis of Electrical Treeing in Polyethylene by Micro-Infrared Spectroscopy

Regular infrared spectroscopy is utilized to research the debasement locale after electrical treeing in polymers. Be that as it may, the measurement of the infrared light spot is too vast contrasted and the tree channel and the position of the light spot is uncertain. Thusly, the smaller scale infrared spectroscopy is proposed in this paper, which is plan to do synthetic investigation for electrical tree range in polyethylene at a micrometer scale. An inclined air conditioning voltage was connected for electrical tree initiation in polyethylene, using a wire-plane terminal structure. Cuts of tests with electrical trees were then examined through small scale infrared spectroscopy. The trademark bunch dispersion inside a chose treeing zone was given through smaller scale infrared mapping. The examination comes about demonstrated the presence of C=O, C-OH and C-O-C gatherings, and the substance of C-OH and C-O-C gatherings was more than C=O gathering. The presence of C=O gathering was went with the C-OH gathering, and the last absorbance is higher, so it is construed the C=O assemble have a tendency to debase additionally as per the Norrish sort II administration. What's more, not all the electrical tree region had the oxygen containing gatherings. The material corruption amid electrical treeing was examined with and without oxygen.

Charge transfer and tree initiation in polyethylene subjected to AC voltage stress

An electrical tree is grown in the region of a dielectric subjected to an intensified local electric field. It can be artificially generated in a specimen by using a needle-to-plane electrode configuration. It is characterized by an incubation period which usually tends to decrease with applied voltage. During this period, charge carriers (electrons and positive holes) move back and forth repeatedly between the electrode and the dielectric. This repeated charge transfer is believed to be mainly responsible for tree initiation. Two main contributions can be conceived: the space charge buildup and the attack on the polymer chains by high-energy charge carriers. A space-charge distortion model is proposed for the initiation of an electric tree in polyethylene. This model can also include material aging processes initiated by injected carriers. It can explain ultraviolet light emission and morphological effects which are experimentally observed in association with tree initiation.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

高温領域におけるポリエチレンの交流トリー発生に対する酸素の効果

高温領域におけるポリエチレンの交流トリー発生に対する酸素の効果

The influence of morphology on electrical tree initiation in polyethylene under AC and impulse voltages

AC and impulse voltages were applied to needle electrode specimens modeling the interface of the semiconducting layer and insulation of XLPE (cross-linked polyethylene) cables. TEM (transmission electron microscope) photographs of minute trees ( >

Influence of metallic electrodes on electrical tree initiation in polyethylene

The nature of electrical tree initiation in polyethylene is treated with a focus on the influence of the nature of metallic electrodes on the initiation voltage. It is shown that the latter parameter varies linearly with the work function of the oxide-covered metallic electrode. This suggests that charge injection in polymers depends on the oxide layer at the metal-polymer interface.

Degradation of polymeric insulation due to photoemission caused by high electric fields

The mechanism of electrical tree initiation in polyethylene subjected at AC, DC, and half-rectified AC voltages is studied by an optical technique which is at least two orders of magnitude more sensitive than partial discharge detection. For DC voltage up to 46 kV, no light emission or tree inception was detected in the polymer containing the normal and decreased concentrations of air in its free volume. For AC and half-rectified AC voltages, tree inception only occurred if light, in the visible and ultraviolet ranges, was detected. Photodegradation of the polymeric insulation by ultraviolet radiation can occur when the voltage applied to the polymer exceeds the threshold voltage of light inception such as during switching and lightning overvoltages. This can account for the gradual degradation of the polymeric insulation which ultimately leads to the formation of an electrical tree. By comparing the light emitted from the polymer subjected to AC voltage having half-cycles of different amplitudes to DC superimposed on AC it is shown that the space charge injected into the polymer causes the zero-crossing of the local field in the polymer. This is required for light emission and subsequent tree inception.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

ポリエチレンのトリー発生に及ぼす吸蔵酸素の効果

ポリエチレンのトリー発生に及ぼす吸蔵酸素の効果

Effects of DC Prestressing on Tree Initiation in Polyethylene with and without Needle-Shaped Void

The effects of dc prestressing on tree-initiation in polyethylene wit needle-shaped voids have been investigated so that a comparison between specimens with and without voids could be made. When the polarity of the pulse is the same as the dc voltage, the effect of dc prestressing is negligible on the 50%-tree-initiation voltage. On the other hand, the opposite polarity gives a significant effect. For the dc prestressing test with the opposite polarity, the effect of the dc prestressing disappears in 2000 s for the specimen with void, and 4000 s for the specimen without void, using -16 kV dc prestressing voltage. In positive dc prestressing tests, the effect of the dc prestressing disappears in 5000 s under 16 kV dc voltage for the specimen without void. For the specimen with void, however, the recovery time is only 100 s.

Effects of Electrode Materials on Tree Initiation in Polyethylene under Switching Surge Conditions

This paper presents the results of the effects of electrode materials on tree initiation under switching surge conditions. Four kinds of electrode materials were used. Also, the effects of oxidized Al on the tree initiation was investigated. When a positive switching surge is applied to the needle in a point-to-plane test, little difference is found to exist among the four electrode materials with respect to the stress at the tip of the needle, Emax required to produce a tree. When a negative switching surge is applied, it is found that there are large differences of Emax. The value of Emax increases with the work function of the electrode materials. In addition with negative polarity, Emax increases with the rise time of the impulse wave in a manner which is related to the interaction of work function and space charge effects. It is noted that oxidized Al has a higher Emax than non-oxidized Al. When a positive half cycle wave follows a negative half cycle the value of Emax for the positive pulse is reduced from the value for a unipolar positive pulse by an amount which correlates with the work functio of the electrode.

Effects of Charge Injection and Extraction on Tree Initiation in Polyethylene

Initiation of electrical treeing in polyethylene is discussed with the emphasis of a charge injection and extraction process, which is considered to feature the incubation period during which there are no apparently visual change and no detectable partial discharges. Some evidences for the process are shown by electrical, thermal and optical liberation of charge injected from a metal electrode into polyethylene. Effects of metal work functions on tree formation are demonstrated. On the basis of the above find- ings, a field emission and equi-energy theory is proposed for tree initiation and a derived V-t characteristic explains experimental results better than the common power law (t ?V-n) for lifetime.

Effects of Needle Electrode Materials on Tree Initiation in Polyethylene by Applying Impulse Voltage

Effects of Needle Electrode Materials on Tree Initiation in Polyethylene by Applying Impulse Voltage

Tree Initiation in Polyethylene by Application of DC and Impulse Voltage

The results of tree-initiation tests using impulse voltages show that the time required for the build-up of space charge at 25C is 30μs~80μs. The results of prestressing tests with DC and superimposing impulse voltages show that the space charges are homo-charges. An investigation of tree-initiation in polyethylene was carried out using dc and impulse voltages, the latter having a wave-front duration ranging from 1 μs to 700 ps. The relationship between the tree-initiation voltage and the duration of the wave-front of the impulse voltage shows that the times required for the build-up oif the space charge at the tip of a needle electrode are 30μs~140μs at 40C for both polarities and greater than 700 μs for the positive needle and 80μs~l40μs for the negative needle, respectively at 60C. The tree i Ltiation voltage decreases when the impulse voltage is superimposed on a dc voltage of the opposite polarity and increases when the impulse voltage and the dc voltage are of the same polarity. Some of the samples were prestressed with dc voltage for 10 minutes, and were then subsequently tested by applying an impulse voltage with a wavefront duration of 1 μs after a waiting period of 2, 30 and 60 minutes, respectively. The tree-initiation voltage was reduced in a similar manner as when an impulse was superimposed on a dc voltage of opposite polarity.

衝撃電圧および直流電圧によるポリエチレン中のトリーの発生

衝撃電圧および直流電圧によるポリエチレン中のトリーの発生

ポリエチレンにおけるトリーの発生機構

ポリエチレンにおけるトリーの発生機構