当动、静触头在操作机构的作用下分闸时，触头间产生电弧，触头表面在高温下挥发出蒸汽，由于触头设计为特殊形状，在电流通过时产生一磁场，电弧在此磁场作用下沿触头表面切线方向快速运动，在金属圆筒(屏蔽罩)上凝结了部分金属蒸汽，电弧在自然过零时就熄灭了，触头间的介质强度又迅速恢复起来。
When the dynamic and static contacts are switched off under the action of the operating mechanism, an arc is generated between the contacts, and the surface of the contacts evaporates vapor at high temperature. Because of the special shape of the contacts, a magnetic field is generated when the electric current passes. Under the action of this magnetic field, the arc moves rapidly along the tangent direction of the contact surface and condenses on the metal cylinder (shield cover). With some metal vapor, the arc is extinguished when it passes zero naturally, and the medium strength between the contacts is rapidly restored.