ON ARC ENERGY ABSORPTION BY COOLING DEVICES I ELECTRICAL INSTALLATIONS

摘要

Internal arcs in electrica 1 installatio n s he at up he surround ing g as and by t his c ause overpressure, which may excee d th e mechanic al streng th of the installation. Personal may be endangered by parts of the installation flying off and by escaping hot gases. In order to control overpressure , relieffla ps are installed in general. Hot gase sflowing out through these openings lead to overpressure even in the installation building, which occasiona llymigl exceed the mechanical strength of the walls. A possible measure to reduce the stress to the building is the use of arc energ y absorber s (coo ling grids). These grids from e.g. expande d meta1 are placed in the flow of the hot gases. They are heate dup by thermal conducti on. Th is red uces the energy input into the surroun ding gas and ovspressure in the building. Exploratory investigati ons a re perfor me d in or der to estimate the efficiency of such absorbers, its influence on the overpressure development and its influence on the gas flow resistance in dependence of the type of cooling grid, its rumber in series and hedistance from the arc, respectively. Amodel is proposed to describe the cooling effect of the absorbers in a CFD tool for overpressure calculation.