Gas flow analysis in low energy arc puffer interrupters

Puffer interrupters, which use the gas blast produced by relative movement of a piston and a cylinder, are widely used due to their compact size, simple structure and excellent interruption properties. For puffer technology, the interruption capability depends on the interaction between arc, gas flow, pressure build up, nozzle material and geometry. The interrupter is divided into two main compartments with the same initial pressure. During arc interruption, the gas in the arcing zone is heated resulting in higher pressure. The pressurized gas from the other compartment blasts into the arcing zone and helps to extinguish the arc. Puffer design plays an important role in determining puffer pressure build up. In this paper computational fluid dynamics (CFD) simulations are used in order to understand the complex phenomena inside puffer interrupters during switching of medium voltage load currents. Two different nozzle geometries have been investigated using CFD modeling. In order to validate the simulation results, experiments have been conducted in a high power laboratory and compared with simulation. Understanding the gas flow and pressure build up during current interruption helps to develop a puffer interrupter that provides higher performance with better reliability in a more compact size. Optimizing the nozzle geometry and controlling the leakage rate inside the puffer breaker result in higher pressure build up and better interruption performance.