A STUDY ON TEMPERATURE DISTRIBUTION OF THE HIGH VOLTAGE PORCELAIN INSULATOR STRING

Nowadays, porcelain string insulators are commonly used in high voltage transmission lines. The study of temperature distribution is extensively performed in the design and development of high voltage insulations. As known, the infrared technology has opened the door to a variety of applications and especially it is also used as a kind of non-contact remote detection technology which has the advantage for detecting high voltage faulty porcelain insulator. Thanks to it, this paper uses the infrared technology to investigate the temperature distribution of the 220kV power grid insulator string. The experiments were done in climate chamber to study. Firstly, determining the thermal stability time of the high voltage porcelain insulator called XP-70 type composing of 14 pieces under the tested voltage of 127kV based on the temperature and voltage distribution. And then the temperature distribution along the normal and fault insulator string experiments. The experimental results show that it may detect and compare the insulator metal cap temperature of faulty insulator in the porcelain insulator string and determine the location of them. And especially based on the unchangeable voltage distribution, it may detect the temperature distribution characteristic for the fault insulator string. Therefore, this research results can provide a reference to detect the faulty porcelain insulator strings

Influence of temperature on structural-phase changes and physical properties of ceramics on the basis of aluminum oxide and silicon

The purpose of this experiment was to prepare high-voltage porcelain ceramics as local raw materials. Density, water absorption, and volume shrinkage were determined according to the State standard (GOST 7025-91). A structural analysis was carried out using a scanning electron microscope, and an X-ray phase analysis was carried out on an Xpert PRO diffractometer. It was found, that in the initial state, ceramics consist of hexagonal (SiO2) and a small amount of monoclinic phase. Above a temperature of 1150 °С they consist of hexagonal (SiO2), an orthorhombic lattice, and also contain mullite (Al2Si2O13).

Failure Trends of High-Voltage Porcelain Insulators Depending on the Constituents of the Porcelain

The aging of porcelain insulators is responsible for the failure of power utilities. Porcelain insulators from different places in South Korea, possessing various aging times and years of installation, have been investigated to carry out lifetime statistics. These samples have a mass of 36,000 lbs and are operated at 154 kV. X-ray fluorescence (XRF) and scanning electron microscopy (SEM) were performed on the porcelain bodies of the samples collected. XRF and SEM revealed trends in the weight percentage of SiO2, Al2O3, and Fe2O3 in the porcelain bodies of the collected samples. The SiO2 and Fe2O3 weight percentage reduced to 8.93% and 73.17%, respectively, in sample C compared to A. However, the Al2O3 weight percentage increased to 16.23% in sample C compared to sample A. This change in weight percentage of SiO2, Fe2O3, and Al2O3 contributed toward enhancing the mechanical and electrical properties of the insulators. Mechanical load tests with electrical voltage (M&E), thermal and mechanical load tests (T&M), and hardness tests (HRB) were performed to evaluate these characteristics. Experiments revealed an increase of 90.9% in the inequality factor (K) in sample C compared to A. The impact of constituents of porcelain on the lifetime expectancy of a porcelain insulator was reported by implementing statistical strategies, such as the Weibull distribution.

Evaluation of Tanzania local ceramic raw materials for high voltage porcelain insulators production

This study evaluated the potential of locally sourced-ceramic raw materials in Tanzania, Pugu kaolin, Same clay, vermiculite and feldspar, for production of high voltage porcelain insulators. The chemical, mineral phases and microstructural characterization of raw materials and porcelain samples were carried out using the X-ray fluorescence, X-ray diffraction, and scanning electron microscopy techniques, respectively. The mineral phases of the fired porcelain sample identified were mullite and quartz. The porcelain bodies were fabricated using the dry pressing method by varying the composition of the selected ceramic raw materials. The physical-mechanical properties and dielectric strength were measured for each porcelain sample. The sample with the composition of 20% Pugu kaolin, 20% Same clay, 20% vermiculite and 40% feldspar was found to have the dielectric strength of 50.8 kV.mm-1, bending strength of 20 MPa and water absorption of 0.46%, which satisfies the main requisite properties for high voltage porcelain insulators.