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In this paper we investigated the space charge accumulation characteristic in single and multi-layered samples composed of EPR laminated on top of LDPE. We measured when the polarity of the applied voltage was reversed and moreover, we compared the results to these obtained when a short circuit was provided before the voltage reversal.
In this report, we study of fundamental research for a high positional resolution of pulse electro-acoustic (PEA) method. Positional resolution of PEA method depends on a pulse width of the applied pulse voltage and a traveling time of the acoustic signal through a piezo electric sensor. Our laboratory tried to develop a thin sensor using the polyvinylidene fluoride (PVDF). Consequently, we succeeded...
Many research works have been reported on space charge accumulation characteristic in polyethylene based materials, which are used as a power cable insulating material. In these reports, some of them show the relationship between the space charge accumulation and dielectric breakdown under DC high electric field. For example, Matsui et al, showed that the packet-like charges injected into Low-Density...
The space charge accumulation in polymeric materials is one of the important behaviors of pre-ageing phenomena in electrical insulations. The Pulsed electro-acoustic (PEA) method is an appropriate method to understand the space charge behavior, but some kind of charges such as charges with high speed are hardly detected by the method. To understand the whole information of charges, that is Q(t) behaviors,...
Printed circuit boards for communication equipment have been promoted by mounting circuits in them with higher-density. It is said that an ECM (Electro Chemical Migration) generates in the insulating material when a high electric stress is applied to the board material under high temperature with high humid condition. Since the ECM degrades the insulation properties of it, it is necessary to use a...
We have developed a new method “direct current integrated charge (DCIC) method” for evaluating a deterioration of insulating materials in power equipments. The three important dielectric parameters, that is, conductivity, relative permittivity, and accumulated charge amounts are evaluated simultaneously by a relatively simple treatment of the method. Since the total amount of charges is found as an...
In this paper we investigated the space charge distribution that accumulated inside multi-layered polyimide films and the breakdown characteristics in them when applying a high DC voltage. The multi-layered samples were composed of a 125 µm thick film laminated on top/underneath a 25 µm thick film. The samples were treated at a high humidity (80 %) beforehand, since it is known that when polyimide...
In the automotive industry, a reduction in CO2 and low fuel consumption is required from the view of environment. According to such demand, electric vehicle using an inverter fed motor is developed and diffused. However, partial discharge is generated between motor winding, when the higher voltage is applied to the winding. Thereby, it may induce a fatal breakdown in the cover insulating. Judging...
Irradiating an electron beam to the ETFE, it is thought that electron-hole pairs are generated inside the sample. However, there is no reported cases about this problem. Therefore, by using a blocking layer to block the charge injection from the outside, an inside of an irradiated sample electron-hole pairs were investigated whether it is produced in the DC stress.
In this study, we examined the accumulation mechanism of the space charge in a covering insulating material of motor windings under high voltage based on measurement results of space charge distributions. In these days, the inverter-fed motor drive using pulse width modulation control is applied to many electric devices for industrial machinery, automotive, railway cars and so on. For further improvement...
A positional resolution of space charge measurement system of a pulsed electro acoustic (PEA) method is tried to improve using a newly designed upper electrode unit and a new pulse generator. The improved upper electrode unit with a good terminator contribute to reduce the inductance and it results in reduce a noise. Moreover, in order to apply a pulse voltage to a sample efficiently using a newly...
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