In the absence of an electrical discharge or extreme heat (>500°C), SF₆ is chemically inert. When a discharge occurs, fluorine atoms on the SF₆ may capture an electron and dissociate from the sulfur. When the discharge has ended, under ideal circumstances, each dissociated fluorine loses the captured electron and recombines with a dissociated SFx species to reform SF₆ (Figure 1). This is the ‘self-healing’ or regenerative property of SF₆. Regardless of circumstances, this is the predominate reaction occurring in SF₆ filled high voltage electrical equipment. A discharge does not result in each SF₆ in the discharge path being completely dissociated. Instead, a distribution of dissociation products is formed that looks something like the distribution shown in Figure 2. The amplitude of the distribution is determined by the duration of the discharge and the composition of the distribution is determined by the energy of the discharge. Discharge durations and energies can vary considerably (Figure 3). For more details, please see: Using sf6 analysis for condition based maintenance of circuit breakers and gas insulated substations.