Influence of dust pollution on power frequency discharges in rod gaps placed in parallel with insulating spacer

Insulating spacers are commonly used in the bus bars of metal clad switchgears and transformers, as well as in circuit breaker/cable compartments, to enhance the dielectric integrity of inter-phase and phase to ground insulation. This experimental investigation presents the role of dust pollution on discharges due to power frequency stresses on rod electrodes in the presence of parallel insulating spacers. Gap length and spacer distances from the interelectrode axis were varied to investigate the influence of dust film on breakdown voltage and pulsative corona characteristics. The results show that the presence of the spacer tends to considerably influence the effects of dust pollution on the discharge characteristics. The paper discusses the controlling mechanisms of these variations as well as the impact of the observed results on the performance of air gap clearances of the power apparatus