Question

Why do DC loads cause the greatest reduction in the life of a relay compared to AC loads?

A. DC loads produce higher current levels than AC loads.
B. DC loads produce higher voltage levels than AC loads.
C. DC loads generate more heat than AC loads.
D. DC loads cause more mechanical stress on the relay contacts than AC loads.

Answer 1

DC loads cause more mechanical stress on the relay contacts compared to AC loads, leading to a reduction in the relay's lifespan.

Step-by-step explanation:

DC loads cause the greatest reduction in the life of a relay compared to AC loads because they cause more mechanical stress on the relay contacts than AC loads. When a relay switches off a DC load, it needs to break the continuous current flow, which generates an arc across the contacts. This arc creates high temperatures and can cause the contacts to wear out more quickly. In contrast, with AC loads, the current goes through zero 120 times per second, allowing for a quick opportunity to extinguish these arcs and reducing the mechanical stress on the contacts.