S. Ahmad

Prediction of salt contamination on high voltage insulators in rainy season using regression technique

The severity of contamination on the high voltage insulator surfaces is the significant factor in determining the level of outdoor insulation and in choosing the types of insulators. In the equatorial region, the most dangerous kind of contamination is salt contamination. A regression technique has been used to develop a modified equivalent salt deposit density (ESDD) mathematical model with respect to meteorological conditions. This model provides a useful way for predicting contamination level and for determining frequency of washing the insulators in a given contaminated area.

Contamination of high voltage insulators in the east coast of Peninsular Malaysia

Rapid urbanization and industrialization in Malaysia over last two decades has resulted in increased demand for reliable electric power. The reliability in turn is greatly influenced by the grid system and its components being properly maintained. One of the important components is the high voltage insulators used in the switchyards, overhead lines, substations and power stations. A common phenomenon in the east cost of Peninsular Malaysia is rapid buildup of salt contamination on high voltage insulators due to the salty wind coming from the South China Sea. The main objective of this paper is to develop a mathematical model correlating equivalent salt deposit density (ESDD) with the hydro-meteorological variables. The data collected at one of the plants in the east coast during the dry season has been used to develop the model by using multiple regression analysis. This model has been validated for predicting contamination accumulation level during the dry season.

Sea salts contamination pattern on high voltage insulators in Littoral region of Peninsular Malaysia

This paper describes series results of experiments conducted at Paka Thermal Power Station, which is located near the East Coast of Peninsular Malaysia. More than 12 samples of typical cap-and-pin glass insulators that are commonly installed on electrical power transmission lines are used in the experimentation. Three types of insulator topology are employed, single units, suspension-type and tension-type. These un-energized insulators are allowed to be exposed to 3-4 months duration of sea salts contamination. Equivalent salt deposit density (ESDD) measurement is conducted to measure insulators contamination level. It was found that salt accumulation on suspension type insulator is much heavier than the tension type. Also the direction of inward coming winds has some influence on the salt deposition to the insulator surfaces. Experiments showed that ESDD increases linearly with an increase in time of exposure. This work will help in the establishment of maintenance policies especially in the months of monsoon when generally many utilities thought that during these months maintenance of insulators is not necessary.

Flashover phenomena of polluted insulators energized by AC voltage

The study of polluted insulator flashover mechanism very important for electric power transmission reliability, efficiency and serviceability. In this paper, a new mathematical model based on Ayrton arc voltage gradient equation, which takes account of total resistance of the polluted insulator rather than the pollution resistance value has been proposed. The expression of total resistance of the insulator is also derived. The value of critical flashover voltage (CFV) obtained from the model is in good agreement with the ones obtained through experimental results.

Study of creepage distance of the contaminated insulator in correlation with salt deposit density

For design purposes, the specific knowledge about the creepage distance of the insulator for the contaminated environment is important. This can be done easily if the mathematical relationship between the creepage distance and Salt Deposit Density (SDD) is known. In this paper, a relationship between the creepage distance of the insulator and SDD has been proposed using the Dimensional Analysis technique. The results calculated from the proposed expression are compared with other results and found to be in close agreement.

Analytical assessment of industrial contamination level on outdoor high voltage insulators at western region of Peninsular Malaysia

Salt is the main pollutant in the areas, which are very close to the sea, whereas in areas of industrial pollution the pollutants are coals, cement dust, chemical fumes and soot. This pollution, when moistened by light rain, mist or fog, produces an electrolyte on the surface of the insulators, which may reduce the breakdown voltage of the insulator. Eventually flashover will take over. The insulation level of power lines in pollution mainly depends on operating experience, the kinds of pollutant substance, pollution severity and weather conditions. In an environment where pollution conditions are severe, and maintenance-free insulation design policy cannot always be adopted due to practical and economic constraints, there is a need to determine the best compromise between the design insulation level and frequency of maintenance.

Development of mathematical relation between ESDD and wind velocity for a contaminated insulator in Malaysia

Insulator contamination has been identified as the most important design parameter for external insulation of the high voltage network systems. Wind and electrostatic field plays an important role in transporting and depositing of that contamination over the insulator surface. This contamination severity on the insulator surface can be expressed and represented by Equivalent Salt Deposit Density (ESDD). The values of ESDD can be determined easily through a closed form of mathematical relation. In this paper, a mathematical relation between ESDD, wind velocity and leakage distance of the insulator has been proposed using Dimensional Analysis technique. The results obtained from this analytical expression have been compared with the practical data, which are collected from the Paka Thermal Power Station and good agreement are observed at lower wind velocity.

Dimensional analysis for contamination severity assessment on high voltage insulators

The environmental pollution which is mainly affected by the weather conditions are the main cause of flashovers on high voltage insulators leading to outages in power systems. It is generally recognized that the worst type of pollution that lead to the contamination flashovers is marine pollution as found in the immediate neighborhood of the coastal regions followed by solid pollution as found in the dense industrial areas. This research is directed towards the study of contamination of insulator under marine pollution. The effects of various meteorological factors on the pollution severity have been investigated thoroughly. The mathematical relations between equivalent salt deposit density (ESDD) with refer to meteorological conditions such as wind speed, rainfall and surface conductivity has been derived using Dimensional Analysis. It has been proved that the Dimensional Analysis technique is suitable for the contamination studies and assessment on the insulators. The predicted ESDD has been compared with the measured for a practical system.

Development the relationship between ESDD and the distance from the source of contaminants for the insulator

The contamination severity on the insulator surface can be expressed by equivalent salt deposit density (ESDD). The value of ESDD varies with the distance of the insulator from the source of contaminants. Normally, the main sources of contaminants affecting insulators are coming from the coastal regions, industrial areas and also deserts. The values of ESDD tend to decrease with increasing distance from the seacoast. In this paper, a relationship between the ESDD and the distance of the insulator from the source of contaminants has been derived based on dimensional analysis technique. The results obtained from the proposed relationship are compared to the other researchers results and good agreement is observed. With this finding, effective implementation of line and station insulation coordination in contaminated conditions will be obtained.