Risk parameters of DC fault arcs - research work on DC arcs in LV systems

摘要

Today there is an increasing number of DC applications where powerful DC fault arcs are likely to occur. These arcs are of potential risk for persons while working at the DC power equipment. DC arc conditions have not yet been analysed very well. There is a lack of information and detailed strategies on how to protect workers against short-circuits with fault arcs in DC power systems. Laboratory measurements of DC systems were started with electric parameters which are comparable to those of the Box Test of Personal Protective Equipment (PPE) according to IEC/EN 61482-1-2 (LV, short-circuit currents of some kA) for sampling knowledge in the field of DC fault arcs and personal protection by PPE. First measurements took place in test circuits supplied by a Li-Ion car battery. A High-Volt battery with a varied number of modules was used. Furthermore measurements were carried out in a similar test circuit supplied by a DC induction generator. The no-load voltage was varied between 100 and 750 V, the prospective short-circuit current between 1 and 6 kA. Electrode arrangements of opposing electrodes of different materials with and without box (similar to the Box Test) were used in these DC arc tests. The electric arc parameters and the arc thermal incident energy were measured. Aim was to sample knowledge on the DC arc and risk parameters, and obtain information on arc power and energy levels to be expected in DC systems. The paper summarizes the first analysis results. Similarities and discrepancies of AC and DC arc hazards are considered. Principle correlations and tendencies are derived. The results have to be verified and extended by further research work.