A slight potential difference develops between the input and انواع رله output terminals of a relay contact during current flow

Even a few millivolts of loss may trigger malfunctions in sensitive electronic environments

The drop happens because even the best conductive materials used in relay contacts have some inherent resistance

When current passes through this resistance, energy is lost as heat, resulting in a voltage difference between the input and output sides of the contact

This voltage drop becomes more noticeable under high current loads

In applications like motor controllers or heating circuits, resistances as low as 50 milliohms can yield drops exceeding 300 mV

In precision analog systems—including 3.3V or 5V sensor networks—this loss can disrupt signal integrity

A 5V-requiring sensor receiving just 4.8V may output erroneous data or trigger erroneously

Prolonged exposure to voltage drop introduces cumulative degradation

Repeated switching under high current can cause the contact surfaces to erode or oxidize over time

Higher resistance elevates the potential difference, deepening the energy loss

This thermal runaway cycle exponentially worsens contact condition over time

In severe cases, contacts may permanently stick closed or become entirely non-conductive

Ambient heat compounds the thermal stress on relay components

High ambient temperatures combined with the heat from voltage drop can push relay components beyond their rated limits

In sealed or cramped electrical cabinets, heat dissipation is severely limited

Excessive heat accelerates insulation breakdown and metal fatigue, shortening operational life

Designers must prioritize relays with sub-50mΩ contact resistance and match ratings to peak current demands

Silver-cadmium oxide or silver-nickel contacts offer superior conductivity and arc resistance

For mission-critical systems, combining snubber circuits with SSRs eliminates mechanical wear entirely

Regular maintenance and inspection of relays in high duty cycle environments can also help catch early signs of contact degradation

Measuring real-time voltage at the load terminals uncovers hidden losses

Proactively managing voltage drop ensures stable performance, minimizes downtime, and protects sensitive equipment