Difference between Electromechanical Relays and Solid State Relays

There really is no right or wrong answer to the question of “which is better, solid state relays or electromechanical relays?” You’ll hear different things with different reasons, depending on who you ask. It’s best to learn the differences between the two and make that judgement for yourself.

In general, a relay is a power switching solution that is used to allocate power without manually opening and closing the switch. It’s a gatekeeper of sorts for larger electrical signals, using a small electrical signal in order to switch the power on and off. There are many different types of relays-thermal, reed, electromechanical, solid state, and hybrid-of which, two are the most popular, electromechanical and solid state.

An electromechanical relay (EMR) uses electromagnetic forces form a low-power input signal to physically move a part and connect two contacts in order to complete a circuit that contains a high-power signal. It can lead to internal arcing and take a relatively long time to move, but it is useful in many situations due to their simplicity, lower cost, and thermal management.

A solid-state relay (SSR) uses low-power signals to generate optical semiconductor signals that transmit and energize the output signal. The input optical signal acts as a “switch” that allows the high-power signal to pass through. There are many types of SSRs, but they all lack moving parts, hence the name “solid state”.

Both EMRs and SSRs can be used in circuits for heating, lighting, motion control, etc. But, when it comes to comparing specs, SSRs, as a newer design, outperforms EMRs in most categories. SSRs are more complex and unable to do any sort of thermal management, thus requiring integrated heat sinks and fans, incurring more costs. But, SSRs are faster, generate minimal electrical disturbances, use less power for higher output, are more resistant to shock and vibration, and are more suitable for more applications, even those in harsher environments.

Veritable Aviation, owned and operated by ASAP Semiconductor, is a premier supplier of reed relays. With a wide variety of parts and components for the aerospace, aviation, and defense industries, and 24/7x365 customer support, we’re always available and ready to help you find all the parts you need, new or obsolete. If you’re interested in a quote, email us at sales@veritableaviation.com or call us at +1-503-374-0340.


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September 16, 2019

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