Electro-mechanical relays versus solid-state relays

For all-purpose usage:

Electro-mechanical relays can be used for many purposes because they can function in AC and DC load circuits. When their contact is open, the relays do not allow any leakage current to flow through. The closed contact has a low resistance and creates only minimal power loss in the load circuit. Multiple contacts are also possible so that a control signal can simultaneously switch multiple contacts and thus multiple load circuits. Electromagnetic relays are also very insusceptible to transients.

However, in contrast to solid-state relays, the moveable contacts and reset springs found in mechanical relays are susceptible to wear and tear.

For specialized usage:

Solid-state relays boast a long lifespan and superior reliability when exposed to shock and vibration. They are small-sized, require less control power, and have very short response times. Loads can be switched with no bounce and no switching noise is generated. Neighbouring components cannot be disturbed during the switching process by the electromagnetic radiation typically caused by coils or switching sparks. However, when compared to mechanical relays, the solid-state relays experience more power loss on the load circuit. For this reason they are often mounted on a heat sink.

The choice between electro-mechanical and solid-state relays should then be made based on the requirements of the application field, whether it is isolating potentials, conditioning signals, or amplifying switching.

The MICROSERIES and RIDERSERIES relays have an outstanding price-performance ratio. With control voltages from 5 to 230 AC/DC and switching capacity up to 250 V AC/16 A, they are suitable for all industrial applications. From one to four CO contacts are available with a variety of different contact materials.

The TERMOPTO from Weidmüller provides a compact, electronic alternative to electro-magnetic relays. The contact terminals feature integrated isolation of potentials and require no servicing. They save space, minimize service overhead, and reduce the probability of facility outages. Weidmüller has developed the MICROOPTO-SOLENOID for loads up to 10 amps. It is a short-circuit-proof switching amplifier with an alarm contact that is specially designed for switching inductive loads.