The electrical life of a relay refers to the number of times or time that it can reliably perform on-off operations without failure under specified normal operating conditions. However, in actual applications, automotive relays are often affected by various mechanical stresses, among which shock and vibration resistance are two key factors.
When an automotive relay is subjected to a strong impact, its internal contacts may shake. This shaking causes the contacts to switch quickly between closing and opening, resulting in sparks or short arcs between the contacts. Sparks and short arcs generate high temperatures, causing the contact material to burn, melt or evaporate. Over a long period of time, the contact surface will become rough and uneven, the contact resistance will increase, and it may even cause the contacts to stick or fail to close. Contact burnout will directly affect the on-off performance of the relay and shorten its electrical life.
Impact may also cause loosening or damage to the internal structure of the automotive relay, such as spring deformation, coil displacement, and shell cracking. Loose structure will change the mechanical matching relationship inside the relay, resulting in insufficient contact pressure or obstructed movement. Damage may directly destroy the key components of the relay, making it unable to work properly. Looseness and damage to the structure will reduce the reliability and stability of the relay and accelerate the attenuation of its electrical life.
Under the impact, the closed contacts may be disconnected instantly, and the open contacts may be closed instantly. This instantaneous on-off phenomenon will disrupt the normal working rhythm of the relay and cause current and voltage fluctuations in the circuit. For some sensitive circuits, this fluctuation may cause misoperation or damage other components. Instantaneous disconnection and closing failure will reduce the control accuracy and reliability of the relay, thereby affecting its electrical life.
In a vibrating environment, the moving parts inside the relay will continue to move relative to each other. This relative movement will cause friction and wear, resulting in gradual loss of surface material of the parts. At the same time, vibration will also cause noise, affecting the use environment and user experience of the relay. Wear will change the size and shape of the parts, affecting their matching accuracy and motion performance. Long-term accumulation may cause the relay to malfunction or fail.
Similar to impact, vibration may also cause the relay contacts to be disconnected or closed instantly. Vibration will change the contact pressure between the contacts, causing the contacts to contact and separate from time to time during the vibration process. This instantaneous on-off phenomenon will accelerate the burning and wear of the contacts. Instantaneous on-off failure will reduce the on-off performance and reliability of the relay and shorten its electrical life.
Long-term vibration will cause loosening and fatigue of the mechanical structural parts of the relay. Looseness will change the matching relationship between the structural parts, resulting in movement obstruction or failure. Fatigue will cause the structural parts to gradually produce cracks and expand under repeated stress, eventually leading to fracture. Loosening and fatigue fracture of mechanical structural parts will seriously affect the structural integrity and working performance of the relay, making it unable to work normally or completely fail.
Vibration may also cause the contact resistance between the relay contacts to increase, or even completely lose electrical contact. Vibration will make the contact surface rough and uneven, resulting in a reduction in contact area and insufficient contact pressure. Over a long period of time, the oxide film between the contacts will thicken, further increasing the contact resistance. When the contact resistance increases to a certain extent, the contacts will not be able to conduct current normally. Increased contact resistance and loss of electrical contact will directly affect the on-off performance and electrical life of the relay.