Standards Development

Scope

The object of this document is to define general requirements for the resistance against electromagnetic disturbances of electromechanical elementary relays, time relays, solid state relays, reed relays and similar automatic switching devices and their limitation of the electromagnetic interference with other equipment. Due to different functional and operating mechanisms as well as different designs, the devices will be referred to uniformly as switching units in this document. The requirements of IEC Guide 107 "Electromagnetic compatibility - Guide to the drafting of electromagnetic compatibility publications" are incorporated herein.

Where the switching units are specified as apparatus (intended to be incorporated into the equipment by the end user without EMC knowledge; e.g. solid-state relays for DIN rail mounting), the devices shall be assessed in accordance with this standard. Switching units intended for incorporation into the equipment by the equipment manufacturer (e.g. relays for PCB mounting) are considered basic components. In this case, the EMC requirements described in this standard may be used by the manufacturer for the evidence of characteristics, depending on their applicability.

Devices within the scope of this document might be operated in different electromagnetic environments; depending on the electromagnetic environment different emission and immunity test requirements are applicable. The analysis and evaluation of electromagnetic compatibility as part of a risk assessment is helpful in determining the necessary specifications by the manufacturer and/or the specific requirements by the user and in defining these for the test procedures in accordance with an agreed test plan. Guidance on risk assessment is given in Annex A.

This document considers as different fundamental types of electromagnetic environments the residential electromagnetic environment, the industrial electromagnetic environment and the energy sector environment (e.g. power stations or substations).

NOTE 1 This document may be applied in other specific product applications (e.g. automotive or railway sector) following consultation between the manufacturer and user, but additional requirements may apply in such cases.Corresponding immunity test requirements are described in Clause 8.

Electromechanical elementary relays and other devices not incorporating additional electronic circuits with active components are not sensitive to electromagnetic disturbances in normal service conditions, and therefore no EMC tests are required.

NOTE 2 Overstressing of the contact arrangement, the coil structure or the insulation of electromechanical relays is to be attributed to limited performance and is not a reason for limited electromagnetic compatibility.

Devices that must fulfil safety functions in industrial applications, as defined in IEC 61508 by specifying a safety integrity level (SIL), may require higher immunity levels. These requirements are not handled in this document.

In terms of emission requirements, equipment shall be classified in Class A or Class B equipment, as per the requirements and procedure of CISPR 11. The corresponding emission requirements are described in Clause 9.

Relevant operating modes of switching units for evaluating EMC behaviour are the OFF and ON states and the switching process with a specified ON/OFF rate. The transition between the switching states is not particularly relevant here. However, the reliable functioning of sensitive electronic control and monitoring circuits must be ensured.