抄録
To determine the very small quantity of salt attaching on pilot insulator for watching insulation characteristics of practical insulator installed in various electric power equipments an energy dispersive X-ray fluorescence method using a particular X-ray tube of small size and low power output was applied. The X-rays from the low voltage X-ray tube, 37.2mm dia. and 85mm length, having the 8μm thick transmission type Ti target and the 0.5mm thick Be window are irradiated on the surface of contaminated insulator, and the Cl KX-rays produced from the salt (NaCl) attached on the insulator are spectrometrically observed by a proportional counter following a multichannel analyzer. To detect faint 2.62keV Cl KX-rays clearly, the elimination of 2.96keV Ar KX-rays generated in air of the X-ray path between the X-ray tube and the detecter was examined by the following two methods: (1) substitution of air by CH4 gas after flowing through a CH4 gas flow type proportional counter, and (2) use of an X-ray filter of 30μm polyvinylidene chloride set up in front of a Ne gas filled proportional counter. The latter method was applied for a 250mm dia. suspention insulator of crevice type, and the attaching salt quantity more than about 0.01mg/cm2 was found to be detectable. The coexistence of dust resulted in decrease of apparent salt quantity because of self absorption of Cl KX-rays with the dust substances. The experimental results obtained by an insulator placed nearby seaside area showed directional distribution of the attaching salt on the insulator surface. The observation of time dependent soil accumulation on insulator surface is also easily practicable by this method.
