Parameter Study of Arc Squeezing DC Breaker : The impact of the geometry on counter force, pressure, and arc voltage

Sammanfattning: The sustainable future in our already electrified world includes solar power generation, battery storage, and electric vehicles all which requires DC systems. DC breakers play a key role in operation and protection within the DC system. Current interruption in DC systems is more challenging than in AC systems due to the absence of natural zero crossing. Some existing interruption techniques are current injection, the use of semiconductors, and arc voltage increase. This thesis project investigates how ventilation geometry, radius, and current level affect the pressure and counterforce in a cylindrical design of a current interruption device based on arc squeezing technology that uses polymer ablation to increase the arc voltage. The purpose is to collect useful data for future product development in this relatively new technology area. The project consists of a pre-study about arc interruption, polymer ablation, and test circuit theory, the test object design phase, the experiments, and this report. The results experiments show that ventilation at the center of the cylindrical arc chamber reduces the pressure by three times compare to a non-ventilated center at the highest test current level. The radius variations did not affect the pressure, it was however seen that the thicker tube, with a higher mass, had a lower initial speed and a slightly higher counterforce. The pressure measurement implemented in the design allow for an additional quantity to analyze in relation to the previously available quantities. Further testing with other design parameter variations such as the length of the stroke, or size of the ventilation holes is the next step for future work.