Relays with positively driven contacts generate a significantly lower power loss than semiconductor relays and therefore do not need to be equipped with heat sinks. In contrast to semiconductor relays, electromechanical safety relays are also very resilient to voltage and overcurrent peaks. A further advantage is the relatively simple design of safety relays that makes it easy for users to recognise failures and their effects.
Semiconductor relays, in turn, have several advantages over electromechanical safety relays. For example, they are subject to less wear because they do not contain any moving parts. In addition, semiconductor relays are built more compactly than electromechanical relays with positively driven contacts.
Therefore, each type of relay has very specific advantages and disadvantages, which means that electromechanical safety relays and semiconductor relays complement each other very well. For this reason, both relay variants are used side by side in many applications.