Space Charge Behavior Research Articles

Space charge behavior in full-size 250 kV DC XLPE cables

The space charge in full size 250 kV HVDC power cables was measured using the pulse-electroacoustic method. Measurements of two types of newly developed DC XLPE cables with 20 mm insulation were taken under a DC voltage of 500 kV with the conductor temperature at room temperature and at 85/spl deg/C. A qualitative analysis of the space-charge distribution and a quantitative analysis of the electric fields in the vicinity of semicon interfaces were conducted. It was shown that the field in the vicinity of the inner semicon tends to increase by 10-40% when the polarity of the applied voltage was reversed, in the case when the conductor was kept at 85/spl deg/C. However, the distortion of the electric field was significantly less than that expected in conventional XLPE cables. As the result, the subjected DC cables are considered to have stable DC characteristics from the viewpoint of space charge-behavior.

エポキシ樹脂中の空間電荷分布の観測

Internal space charge behavior of insulating materials has recently attracted attention of many researchers, and a large number of experimental studies were carried out by using the materials for dc cables, such as XLPE, LDPE, and HDPE. Epoxy resins are used for insulation under strong electric fields in power apparatus and in electronic devices, and we investigated the behavior of internal space charge using the pulsed electroacoustic method. Two types of epoxy resins were studied: insulation-grade and craft-grade. When dc electric fields were applied to the craft resins treated by immersing them into room-temperature water for 8 and 24 h, positive and negative charges accumulated near the anode and the cathode, respectively, and the charge distribution changed with the immersion time. On the other hand, no charge was observed in the insulation-grade epoxy resin. Next, we treated the samples by immersing them into 100 °C water for 8 h. When the sample was treated for 8 h, hetero charge distribution, which means positive charges near the cathode and negative charges near the anode, was observed. This result is consistent with a previous paper reporting that by chemical analysis, secondary decomposition had occurred. These results show that water and temperature influence the internal space charge behavior of epoxy resins. © 1999 Scripta Technica, Electr Eng Jpn, 129(3): 9–16, 1999

プリント基板絶縁層内部の空間電荷の観測

Since a metal-base printed wiring board (PWB) with superior thermal conductivity has been widely used in power electronics products, high reliability is required at high electric field. Many reports have already covered surface' copper ionic migrations on PWBs which occur short-circuits on the board. The migration growing into the depth direction of a insulation layer has been clearly observed recently, and it is revealed that the growth depends on the ionic impurities of the resin.We measured space charge behaviour in the insulation layer to know the relationship between the internal space charge and the ionic migration. The results suggest that internal negative charges are generated at high temperature with high humidity, and that a conductive region is formed near a copper electrode under dc electric field.

Space charge behaviour in maleic anhydride grafted polyethylene/ethylene - vinyl - acetate copolymer laminates

Charge distributions in maleic anhydride (MAH) grafted polyethylene (g-PE)/ethylene - vinyl - acetate (EVA) copolymer laminates have been measured with materials of different composition. All laminates showed interfacial charge, the polarity and the magnitude of which are explained by interfacial polarization. It was found that the interfacial charge increased with the increase of MAH content in the g-PE, whereas it decreased with the increase of vinyl - acetate content in the EVA. This feature was attributed to the differences in electrical conductivity of the materials. Details of the experimental results are described.

Charge behavior in polyethylene-ionomer blends

In order to explain a decrease of thermally stimulated current (TSC) at high poling fields, the behavior of space charge in two types of polyethylene (PE)/ionomer blends, PE/Surlyn 1652 and PE/Surlyn 1601, has been investigated by measuring the charge distributions and conduction characteristics. PE/Surlyn 1601 blends showed smaller current densities at high electric fields than PE/Surlyn 1652 blends. A considerable amount of negative charge was found to migrate into the bulk region of PE/Surlyn 1601 blends upon discharging, which was attributed to the strong electron affinity of ionic clusters existing only in Surlyn 1601. This migration of charge made the charge distribution uniform, resulting in a decrease of TSC at high poling fields. This phenomenon was not found in PE/Surlyn 1652 blends.

The effect of low-molecular-weight species on space charge and conduction in LDPE

We have investigated the effect of low-molecular mass species on the space charge behavior such as space charge distribution and electrical conduction of LDPE (low density polyethylene). We also attempted to explain the relationship between the space charge distribution and electrical conduction. The heterocharge, conduction current and effective charge mobility decreased when the low-molecular-mass species in LDPE was removed. It was found that the decrease in conduction current was related to the decrease of heterocharge in LDPE.

Space charge behavior under ac voltage in water-treed PE observed by the PEA method

The pulsed electroacoustic method (PEA) has been applied to observe space charge formation under ac application (7 kV/sub pk/, 50, 0.1 and 0.001 Hz) in water-treed polyethylene samples in order to understand the degradation mechanism of water trees. A system with phase-resolving capability has been developed to measure the space charge distribution at any phase angle of the applied ac voltage. By comparing the observed charge distributions with theoretically predicted ones, it has been shown that the interfacial polarization due to the difference in conductivity between the treed and the regions without trees dominate the space charge behavior. It has become clear that the PEA method can be a powerful nondestructive method for evaluating water tree length.

ポリエチレン中の空間電荷挙動

ポリエチレン中の空間電荷挙動

直流高電界下におけるポリエチレン中の空間電荷挙動

直流高電界下におけるポリエチレン中の空間電荷挙動

Packet-like space charges and conduction current in polyethylene cable insulation

Packet-like space-charge behavior in polyethylene for cable insulation was studied by utilizing the laser-induced pressure-pulse technique. Space charge observation under various conditions showed that the charge packet was formed in the specimen doped with antioxidant, especially when the specimen is oxidized. Periodic formation and transport of charge packets led to a small current oscillation. The charge packet seemed to be formed in the bulk, and the internal field of 1.2 to 1.4 MV/cm, in the region where the packet was formed was periodically enhanced from 2 to 2.5 MV/cm by space-charge accumulation. This suggests that the packet formation is caused by carrier generation under the highly enhanced field. The antioxidant deteriorated by oxidation was shown to be a possible origin of the carrier generation.

水トリー劣化した架橋ポリエチレンにおける空間電荷の挙動

水トリー劣化した架橋ポリエチレンにおける空間電荷の挙動

Space charge behavior in an antistatic polymer including polymer solid electrolyte

AbstractA polymer dielectric material tends to be easily charged and may cause an electrostatic discharge, due to the serious problems that result when consequent electromagnetic noise damages the electronic circuits in various kinds of apparatus. The antistatic polymers that have been developed to prevent electrostatic discharge contain polymer solid electrolytes so that space charge originally exists inside them. The mechanism of the antistatic discharge effect of the polymer has been investigated by measuring the space charge distribution using the high‐resolution pulsed‐electroacoustic method. The experimental results suggest that the internal space charge of the polymer accumulates at the surface and forms heterocharge distribution at the interface between the electrodes and the specimen. Thus, internal space charge compensates the applied electric field, resulting in preventing the increase of the surface potential. In addition, internal space charge behavior relates to the dispersion condition of the polymer solid electrolyte that depends on the quantity of the electrolytes and the specimen procedures.

Space charge and electrical conduction in Maleic Anhydride-grafted polyethylene

The space charge behavior such as charge distribution and electrical conduction of maleic anhydride grafted LDPE (LDPE-g- MAH) was investigated. Heterocharge was found in LDPE and it decreased with increasing MAH graft ratio in LDPEg- MAH. Conduction currents also decreased with increasing MAH graft ratio. The relationship between the space charge behavior and the electrical conduction characteristics in LDPEg- MAH is discussed.

Characteristic Change due to Argon Ion Etching and Heat Treatment of (Pb, La)TiO3 Thin Films Fabricated by Multiple Cathode Sputtering

The ferroelectric properties of (Pb, La)TiO3 thin films fabricated by multiple cathode rf-magnetron sputtering were investigated. After argon ion etching of the (Pb, La)TiO3 thin films, the reduction of Pb-O bonds, shift of hysteresis loop on the E-axis and the decrease of remanent polarization was induced. After heat treatment at 700° C in N2, squareness and saturation of the loop worsened, and remanent polarization decreased. After reheat treatment of the films at 400° C for 1 h, the coercive field decreased, and the squareness of the loop was improved. These results were discussed from the viewpoint of the behavior of space charge.

ポリマ電解質型帯電防止樹脂中の空間電荷分布の観測

ポリマ電解質型帯電防止樹脂中の空間電荷分布の観測

水トリー劣化した架橋ポリエチレンケーブル

水トリー劣化した架橋ポリエチレンケーブル

Measurement of the internal space charge distribution of an anti-electrostatic discharge polymer

Charged dielectrics can cause an electrostatic discharge (ESD) that damages electronic circuits because of the electromagnetic noise associated with the discharge. Newly developed anti-ESD polymers are expected to be 'anti-ESD polymer insulating materials', but the mechanism of their action against ESD has not been explained. Since the anti-ESD polymers contain some kind of polymer solid electrolyte, they should be able to be characterized by the behavior of their internal space charge. By measuring the space charge distribution of an anti-ESD polymer using the pulsed electroacoustic method under DC electric field, we found that the polymer was effective in preventing ESD because the internal space charge near the surface partially compensates the electric field of the external charge on the surface. We also found indications that the internal space charge behavior is related to the dispersion of the polymer solid electrolyte. >

レーザ誘起圧力パルス法による電力ケーブル絶縁用ポリエチレン中の空間電荷挙動の検討

レーザ誘起圧力パルス法による電力ケーブル絶縁用ポリエチレン中の空間電荷挙動の検討

レーザ誘起圧力パルス法による電力ケーブル絶縁用ポリエチレン中の空間電荷挙動の検討半導電層との界面と酸化防止剤の影響

レーザ誘起圧力パルス法による電力ケーブル絶縁用ポリエチレン中の空間電荷挙動の検討半導電層との界面と酸化防止剤の影響

レーザ誘起圧力パルス法による電力ケーブル絶縁用ポリエチレン中の空間電荷挙動の検討酸化防止剤の効果

レーザ誘起圧力パルス法による電力ケーブル絶縁用ポリエチレン中の空間電荷挙動の検討酸化防止剤の効果