IEC 60085-2004 pdf – Electrical insulation – Thermal classification.
1 Scope This standard gives guidance on the application of international standards in assigning a thermal class to electrical insulating materials (EIM) or simple combinations of such materials (IEC 6021 6-1 ), to electrical insulation systems (IEC 621 1 4) and to insulation for electrical devices. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 6021 6-1 , Electrical insulating materials – Properties of thermal endurance – Part 1: Ageing procedures and evaluation of test results IEC 6021 6-5, Electrical insulating materials − Thermal endurance properties – Part 5: Determination of relative thermal endurance index (RTE) of an insulating material IEC 6021 6-6, Electrical insulating materials − Thermal endurance properties – Part 6: Determination of thermal endurance indices (TI and RTE) of an insulating material using the fixed time frame method IEC 61 857-1 , Electrical insulation systems – Procedures for thermal evaluation – Part 1: General requirements – Low-voltage IEC 621 1 4, Electrical insulation systems – Thermal classification 3 Terms and definitions For the purposes of this document, the following terms and definitions apply: 3.1 electrical insulating material EIM solid with negligibly low electric conductivity, or a simple combination of such materials, used to separate conducting parts at different electrical potential in electrical devices NOTE 1 In English, the term “insulating material” is sometimes used in a broader sense to designate also insulating liquids and gases. NOTE 2 For testing purposes, electrodes may be applied on material specimens without this combination formally constituting an EIS to be tested as such.
3.2 simple combination of electrical insulating materials combination of EIM delivered in joint state for production of devices NOTE For example a flexible material consisting of paper laminated on polyethylene terephthalate film (IEC 60626) constitutes a “simple combination” in this sense. EIMs combined during the manufacturing process of a device do not constitute “simple combinations” in this sense. 3.3 electrical insulation system EIS insulating structure containing one or more electrical insulating materials (EIMs) together with associated conducting parts employed in an electrotechnical device 3.4 thermal class designation of an EIM/EIS equal to the numerical value of the maximum used temperature in degrees Celsius for which the EIM/EIS is appropriate NOTE It may be necessary to assign different thermal classes to the same EIM/EIS for different service conditions. The description of an electrotechnical product as being of a particular thermal class does not mean, and must not be taken to imply that each insulating material used in its construction is of the same thermal capability. 3.5 relative thermal endurance index RTE numerical value of the temperature in degrees Celsius at which the estimated time to endpoint of the candidate material is the same as the estimated time to endpoint of the control material at a temperature equal to its assessed thermal endurance (ATE) 3.6 assessed thermal endurance index ATE numerical value of the temperature in degrees Celsius, up to which the control material possesses known, satisfactory service performance in the specified application NOTE 1 The value of the ATE may vary between applications for the same material. NOTE 2 Sometimes referred to as “absolute” thermal endurance index. 3.7 candidate material material for which an estimate of the thermal endurance is required to be determined NOTE The determination is made by simultaneous thermal ageing of the material and a control material.
4.1 Electrical insulating materials (EIM) Electrical insulating materials and simple combinations of insulating materials shall be evaluated in accordance with IEC 6021 6-5 or IEC 6021 6-6 and refer to expected service conditions. 4.2 Electrical insulation systems (EIS) Electrical insulation systems shall be evaluated in accordance with IEC 61 857-1 and classified in accordance with IEC 621 1 4. 5 Thermal class Since the temperature in electrotechnical devices is very often the dominant ageing factor affecting electrical insulating materials, certain basic thermal classes are useful and are recognized as such internationally. Where a thermal class is specified for an electrical insulating material, this means the maximum used temperature in degrees Celsius for which the EIM is appropriate.