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The porcelain ceramic insulators have been used for outdoor insulation applications for a long time due to their impressive electrical and mechanical properties. The lightning impulse withstand voltage and flashover voltage characteristics of the insulators are important for insulation coordination of transmission lines and substations. This study presents a computer-based simulation methodology to determine the positive polarity lighting impulse flashover voltage of porcelain suspension and station post-insulators. The flashover voltage is determined by evaluating the streamer inception, propagation and sustenance criteria along the suitable paths based on finite-element-method-based electric field computation. The streamer propagation path is found through air along the dry arcing distance rather than along the creepage path of the insulator. The lightning impulse flashover voltage of suspension and post-insulators are computed based on simulation. The comparison of computed results with the experimental results gives a good agreement between them.

Polymer composite insulators acquire the position of their counterpart ceramic and glass insulators in high voltage overhead transmission systems due to their remarkable pollution performance. They have different potential and electric field distributions compared to that of ceramic insulators and the absence of intermediate pin and cap metal fittings makes them compact in size by reducing the distance between energised and grounded ends. This study presents a simulation-based approach to compute the streamer propagation characteristics in polymer suspension insulators under positive polarity lightning impulse voltages. The streamer inception, propagation, and sustenance criteria are evaluated using finite element method-based electric field computations. The significance of insulator geometries on streamer inception and propagation phenomena is well established. The insulator geometries such as weather sheds, location of the first shed, and shed radius have shown a strong influence on streamer inception and propagation path, which govern the flashover characteristics of the insulator. The lightning impulse flashover voltages of different insulators were determined experimentally to validate the computed results. A good agreement is found between simulation and experimental results.

Kangeyam cattle are a draught breed native cattle of Tamilnadu, India. They are well known for their draught power and endurance. The aim of this study is to establish a normal haematological and biochemical values for lactating kangeyam cows. Blood samples were collected from 3 – 4 year old lactating kangeyam cows present in the native tracts of Erode district. Blood samples are used for estimation of haematological parameters like haemoglobin, packed cell volume, red blood cells count, erythrocyte indices, total leukocyte count, platelet count and biochemical parameters like blood urea nitrogen, creatinine, total protein, albumin, aspartate transaminase, glucose, cholesterol, calcium, phosphorous, magnesium, sodium, potassium and chloride. The haematological and biochemical parameters were estimated, statistically analysed and they were in the normal range. It was concluded that these can be used as reference values for lactating kangeyam cattle and also as a baseline data for assessing the managemental practice, physiological status, nutritional deficiency and various diseases of these kangeyam animals.