Electromechanical relays are widely used in manufacturing systems, vehicles, and home devices for controlling power flow. Despite their robust design and proven performance, they are vulnerable to multiple breakdown types that can cause critical system shutdowns or safety hazards.

A prevalent issue is contact wear. Every time a relay switches, a transient discharge happens between the contacts, particularly under inductive surges. Over time, this the sparking consumes the switching electrodes, leading to higher impedance, unreliable switching, or total contact separation. This problem is much more severe in relays that handle continuous switching or handle high currents.

Another frequent issue is contact welding. When a relay closes under high current, the resulting spark creates enough heat to melt the metallic interfaces, causing them to become permanently joined. This results in a relay that fails to release after signal removal, which can be life-threatening in emergency systems.

Winding failure is also widespread. The control coil that triggers the mechanism can fail due to prolonged operation, line disturbances, or dielectric failure. If the coil fails catastrophically, the relay becomes dead because it can no longer generate the magnetic field needed to close or open contacts. This often happens when the relay is driven beyond its voltage tolerance or used beyond its rated cycling limit.

Wear of mechanical elements is another common breakdown cause. The relay internals such as the switch lever, coil spring, and bearing are subject to cumulative stress and wear. Frequent switching can cause reduced return force, leading to lagged switching or sticking in actuated state. Dirt, moisture, or corrosive environments can promote rust and binding by increasing resistance to motion on contact interfaces.

Ambient influence factors also play a substantial part in relay failure. Debris, condensation, and industrial pollutants can build up on terminals or within the enclosure, leading to chemical buildup that blocks conduction that prevent proper conduction. Relays without proper ingress protection may break down early when exposed to prolonged dampness, temperature extremes, or constant physical stress.

Wrong installation can lead to early degradation. Using a relay outside its designed operational limits, or using resistive-rated relays for inductive loads, will trigger premature malfunction. It is vital to match the relay specifications to the environmental and electrical demands, including surge currents and load characteristics.

Routine servicing, underloading practices, and choosing application-optimized relays can help mitigate these failure modes. However, because electromechanical relays have mechanical components, they are naturally constrained by wear compared to solid-state relays. Understanding these known degradation mechanisms allows designers and maintenance staff to create fault-tolerant architectures and schedule proactive replacements before system collapse occurs.