Using Customized Ground Bars
Ground bars are thick bars that are used to ground electrical installations primarily of telecommunication nature. Ground bars can be made of copper, tin, steel or even alloys of any of these metals. Either ground bars or bonding bars are used to create an equi-potential plane service grounds and equipment during fault and transient conditions thus protecting the people and the equipment during the events. This variation in material component is what we are referring to as the customization of these bars.
Ground bars are usually sold with its components including; copper grounding, standoff insulators, and mounting brackets. Their sizes range from 2″ by 10″ to 4″ by 72″. In cases where basic ground bars do not suit the vast uses, custom constructed ground bars are always available as per specifications. It is to be noted that a basic knowledge of the proper installation of grounding bars is vital in providing complete lightning protection. Factors to be considered during the selection of a type of bar to be used; thus, the necessity to customize include; First, the total number of connection locations. Different set ups have different connection intensities. The greater the number of connection location the larger the size of the bar required. This is due to a greater probability of electric leakage. This would also mean more appliances would need to be protected against strikes during lightening.
Secondly, the potential spaces required for future growth. Different stations and industries possess different growth potentials and growth projections. It is therefore of essence during the design to design taking into account the future growth/expansion of the industry. Thirdly, is the size of the linking terminal and conductor. It is always best to ensure that the size of the conductor is proportional to the size of the terminal that links it to the bar; this ensures that the system is not overwhelmed by excess charges induced by lightning strikes in the process of earthing.
Vast types of metals and compounds may also be used due to the fact that they possess different ground resistances. Soils’ level of resistance is dependent on the types of minerals, salt levels and moisture content. Since the earth’s resistivity is not homogenous, soil testing using the Wenner four pole method will determine the best location of the electrode and the type that best suits the soil conditions. In terms of metal compositions, commonly available ground rods are; copper bonded, galvanized, and stainless steel ground rods in different sizes. Stainless steel rods are the best though their high costs prohibit its widespread use.
The major differences between galvanized steel and copper bonded ground bars is their tensile strengths and their service life. The range is from 58000 psi for the galvanized rods to over 90000 psi for the copper bonded steel rods. The higher the tensile strength is then the less likely that the rod will spread when it is being driven into the soil (mushrooming).Service life; this is brought about by the thickness and the type of material used to cover the steel core. Thicker coating would provide better corrosion protection implying longer service life.
In industrial set ups correct choice of ground and bass bars is important. This would be cost effective in the long run. Thus consultancy is advisable during its initial establishment. Tailor made bars are therefore in demand; this is to say customization best suits.
