By the collision of primary electrons having effective energy with hydrogen molecules , when the plasma produced reaches the threshold value resulting in the avalanche effect , the plasma can be regarded as the carrier of a large pulse current , and the conduction of a large pulse current is achieved. Quantitative analysis was conducted for the specific installation and the experiment in details. The said unit is better than other conventional switch gears , with a long performance life, high switch action frequency and good stability , etc. Thus , it
can be regarded as an effective control switch for high demands.