Electromechanical vs. Solid State Relay Characteristics

Electromechanical Relays (EMR) and Solid State Relays (SSR) are very different parts with many differences in characteristics. Here is a comparison table for general cases to help you figure out which type of relay is right for your project.

Characteristics EMR SSR
Sensitivity to withstand misuse or misapplication Good Poor
Sensitive to corrosion, oxidation, or contaminates Yes No
Sensitive to shock, vibration or acceleration Yes No
Sensitivity to radiation Fair Poor
Package versatility Good Fair
Cost per pole Best Fair
Input TTL & CMOS (buffer) compatibility Fair Best
Operate and release time around 5-20 ms around 0.25-10 ms
Compatibility of military/aerospace specs. Good Poor
Ease of troubleshooting Good Poor
Input to output isolation capability around 4Kv >4Kv
Normal failure mode (output) Open Shorted
Normal wearout mechanism Contacts LED

To learn more about how electromechanical and solid state relays compare in output switching capability, please refer to TE application notes on Relay Technologies.

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