28 October 2018
The electromechanical relay is the most frequently used switching element worldwide. Its roots can be traced back deep into the 19th century and originated in the era of telegraphy. Weakened signals were replenished by long lines in the relay station. Current relays are electromechanical masterpieces of the highest precision and accomplish a wide range of tasks in all conceivable industrial areas in different versions. The semiconductor technology (solid state) allows for the development of solid state relays, which, in contrast to electromechanical relays, do not contain any moving parts. The switching is purely electronic and therefore free of wear. These solid state relays are increasingly replacing electromechanical relays in certain industrial sectors. This is especially the case for applications with a high number of switching cycles and high switching frequencies or for applications, where very rare yet very reliable switching is required. However, the versatility of electromechanical relays and their applications are so diverse that the market is still growing worldwide. Regardless of which technology is used for a relay switching circuit, the properties of the application must be known. ComatReleco develops products from both technologies and puts itself forward as a competent partner for all industrial applications with relays.
World of Relays
We will use this workshop to demonstrate how relays and contactors are used. The properties of each application also involve corresponding requirements on the switching components. Knowing all about the application is essential for optimal dimensioning. It is not only important to know the voltage and current of the load, knowing whether the load is ohmic, inductive or capacitive is of equal importance. The switching frequency, switching rate and specific environmental conditions, such as the presence of sewer gases or dusts, but also the occurrence of temperature fluctuations, influence the selection of the relay. In practise – purely from the perspective of switching voltage and switching current – four fields of applications have become established, which can be characterized as follows.
Switching of micro and analogue signals (100 mV / 10uA … 5 V / 1mA)
Switching of control signals (5 V / 1 mA…30 V / 100 mA)
Switching of increased powers / loads (30 V / 100 mA…250 V / 16 A)
High power relays
Switching of capacitive and inductive loads (12 V / 100 mA … 400V / 63 A)