PARTICLE TRAJECTORIES IN A THREE PHASE COMMON ENCLOSURE GAS INSULATED BUSDUCT WITH MONTE CARLO TECHNIQUE

The excellent insulation properties of compressed Sulphur Hexaflouride are adversely affected by metallic particle contamination in practical gas insulated systems. The movement of such particles is random and the particles play a crucial role in determining the insulation behavior of GIS. A Three-phase enclosure-type gas insulated bus (GIB) has widely been applied to minimize the installation space of a substation. To determine the particle trajectories in a three-phase common enclosure Gas Insulated Bus duct (GIB) an outer enclosure of diameter 500 mm and inner conductors of diameters 64 mm spaced equilaterally are considered. Aluminum, copper and silver particles were considered to be present on enclosure surface. In order to determine the random behavior of moving particles, the calculation of movement in axial and radial directions was carried at every time step using rectangular random numbers. Simulation of Particle Movement with Reduced Phase Conductor is also carried out with a view to obtain optimum size of conductor for reliable operation by reducing the original diameter of the conductor from 64mm to 54mm in steps of 5 mm. At each reduced diameter the particle movement is calculated at each instant in both radial and axial directions using Monte Carlo Technique. Monte Carlo simulation is also carried out by changing the random solid angle from 1 degree to 0.5 degrees. The random solid angle is decreased to 0.5 degrees to take into account more smooth end profile of the particle. It is observed that a lower solid angle random movement yields a lower axial movement. It therefore suggests that a more smooth ended wire will have lesser axial movement than a sharp cut wire like particle.