Bus bar arrangement. This topic covers details of bus bar compartment, interleaved bus bar design, major parameters for bus sizing calculation, typical minimum clearances for LV switch gear as per industry practice. Main bus bar distributes power horizontally between the various switchboard columns. Vertical bus bars are connected to the main bus bar. Vertical bus bar provides power to outgoing devices. Bus bar material includes electrolytic grid, aluminum E91e, copper having conductivity 100 percentage IACS or international annealed copper standard, and purity 99.99 percentage. Depending upon three-phase, three-wire, or four-wire, the number of bus bars are three or four. The order of bus bar shall be N, R, Y, B, from front to the rear of the switchboard. Bus bars are provided bear or with heat-shrinkable PVC sleeves to protect against accidental short-circuits and supported by cast resin insulators. The spacing between insulators is determined by short-circuit withstand capability assigned to the switch gear. Joins and Tip-offs are provided with FRP, or fiber-reinforced plastic shroud, as shown here. Bus support insulators are made of molded fiberglass, reinforced plastic, or GRP. GRP has high mechanical strength and can be constructed with ribs to improve electrical tracking property. DMC are dough molded compound or SMD sheet molded compound are also used. All bus bar joints of very high current rating are generally silver coated to reduce the contact resistance for reduction of heat generation. If dissimilar materials like copper and aluminum are used for bolted connection by metallic strips having one side, aluminum and another side as copper shall be used to prevent galvanic corrosion. Bus bar shall be capable of carrying the full load current while keeping temperature rise above the ambient temperature within permissible limits. The temperature rise of bus bars during the rated short-time withstand rating shall also be within limits. For bus bars having lower current rating, one flat conductor for each phase is usually adopted. For higher current carrying capacity, more than one conductor per phase is required. Skin effect and proximity effect result in non-uniform current distribution in each conductor. As a result, current-carrying capacity of two or three conductors having identical cross-section is not twice or thrice of current carrying capacity of a single conductor, respectively. Interleaved bus bar system mitigates skin effects and proximity effects and offers a cost-effective solution. Neutral bus bars are not indicated in the lineup for clarity. Advantages of interleaving, improved current distribution, and low-temperature rise, reduction in electrodynamic forces during short-circuit, low watt loss, and saving in energy. Enhanced life of insulation, reduced voltage, drop. Bus bar sizing calculation is dependent on significant parameters, such as a false level, fault duration, maximum ambient temperature, allowed temperature rise, maximum initial bus bar temperature while carrying full load current, or some of maximum ambient temperature plus allowed temperature rise. Permissible final temperature of bus bar after shots are good for fault duration. The rated impulse, which then voltage of a switch gear, decides the minimum clearance between the bus bar conductor. Earthing. Both b us of GI or copper is provided at the bottom of the LV switch gear, which runs through the entire length of the panel and is connected to the plant Earth at two separate locations from the ends. Here is a quick recap of what you have learned as far. Bus bar conductor material may be aluminum or copper. Main bus bar distributes power horizontally between the various switchboard columns. Vertical bus bar provides power outgoing devices. Bus bars are provided bear or with heat drinkable BBC sleeve. To protect against accidental short circuits. In the conventional bus bars system, conductors of each phase are grouped together. Interleaved bus bar system offers a cost-effective solution for bus bars of high current carrying capacity. Bus bar sizing calculation is dependent on insignificant parameters such as symmetrical fault level and fault duration, maximum ambient temperature, allowed temperature rise, maximum initial bus bar temperature while getting full load current, permissible final temperature of bus bar after shots are good for fault duration.
