Introduction was made to elements of independent innovation for NM6 series moulded case circuit breaker,adopting sealed arc extinguish chamber structure to improve breaking-off capacity and designing a sealed exhaust channel in front of arc extinguish chamber hole to assure zero arc.

The changes of electric potential gradient with time at the given points and the axial distribution at the given time of arc column are measured by means of the differential Probes at different gas pressures and different interrupted currents on a puffer interrupter model.