Electrical fire source simulation for igniting cable

Abstract

In cable fire test,a fire source is essential for the fire performance evaluation. Most of the existing fire sources for power cable are based on chemical fuel,which is unable to represent the cable fire caused by fault arc. Therefore,to simulate the ignition of power cable by fault arc,a fire source based on electrical arc is developed in this work. Firstly,the induced voltage on the metal armor layer is theoretically analyzed when the 110 kV cable has the ground wire stolen or the cross interconnection wires on both sides are stolen. Voltages can reach thousands of volts. Secondly,the pre-breakdown voltage and sustained voltage of the metal-to-ground arc in power cable and the Jacob's Ladder arc are compared. It is found that the breakdown characteristics of both arcs are similar for applied ac voltage with frequencies of 50 Hz and 20 kHz. Thirdly,a fire source based on Jacob's Ladder arc is proposed for the ignition of power cables. Experimental results show that the 110 kV cable can be successfully ignited by this fire source,and the flame is able to spread both vertically and horizontally. Finally,the conclusion is that the high frequency Jacob's Ladder arc can simulate the characteristics of the fault arc and effectively ignite the 110 kV cable.

Keywords

• fault arc
• fire source simulation
• cable fire
• induced voltage
• ladder arc
• arc ignition