This standard applies to the contact sets of all types of relays covered by the UNE 21-136-Electrical relays series of standards. This standard specifies the preferred characteristics of contact loads in the endurance test, within the voltage and intensity ranges defined by the use categories. Preferred values are given for various types of loads including relays and cables. Due to further considerations, the title and values of some tables differ slightly from those indicated in the UNE 21-136/0-20 standard. Functional characteristics of electrical relay contacts. The particular specifications relating to a specific type or model of relay will refer to these preferred values of contact loads, however, for specific applications, additional characteristics may be defined (for example, the connection current in the contact load circuit, lamp load or motor load).