Why Micro Switch Lifespan Differs in AC vs DC Use | Kacon

Why do microswitches fail quickly in DC circuits but last longer in AC circuits, even though both involve pressing and releasing the circuit? The core reason is electric arcing.

In AC circuits, the magnitude and direction of the current change 50 to 60 times per second, with each change resulting in a "current zero-crossing point." At these zero-crossing points, the arcing naturally weakens, minimizing contact erosion and extending the lifespan.

However, in DC circuits, the situation is completely different. DC current remains constant in direction and magnitude, without natural zero-crossing points. The constant voltage continuously fuels the arcing, repeatedly eroding the contact surface.

Under this continuous erosion, the contacts deform and oxidize, leading to poor contact and a significant difference in lifespan. KACON microswitches use silver alloy contacts, offering enhanced impact resistance.