WG 6 - TC 112/WG 6

IEC TR 61858-3:2020(E) provides information on the identification of electrical insulating materials and auxiliary components for the assessment of modifications to an established insulation system and gives guidance on the selection of feasible test procedures.

IEC 61857-32:2019 series is focused on applications where other possible factors need to be incorporated to evaluate any influence on the performance of the electrical insulation system (EIS). Multi-factor evaluation is the most complex type of project to design and conduct. Clear guidelines are needed to give the user of this document a uniform approach and a method to analyse the test results.
This document is for applications where the stresses are some combination of other factors of influence identified in IEC 60505. The multi-factor stresses are applied during the diagnostic portion of each test cycle.
A few examples of other factors of influence or multi-factor stresses are:
– high vibration;
– submersion in oils, water, or solutions;
– voltage higher than the test voltage of the reference EIS;
– decreased cold shock temperature.

IEC 61857-31:2017 establishes an EIS evaluation for applications with a designed life of 5 000 h or less. This test method follows the procedures of IEC 60505 and is modified based on the range of designed life.

IEC TS 62332-3:2016 is applicable to EIM and EIS containing solid and liquid components where the refrigerant, oil and thermal stresses are the dominant ageing factor, without restriction to voltage class.

IEC TR 61857-2:2015(E) gives guidelines to identify the appropriate test method to be used for the evaluation of a proposed Electrical Insulation System (EIS). Some of the standards are for evaluation and classification of the EIS, while other standards identify the appropriate method to evaluate single or multi-factor stresses of a proposed or of an established EIS. This Technical Report is applicable to existing or proposed EIS used in electrotechnical products across a wide range of operating voltages of IEC Standards. The report takes care to select the appropriate standard based on construction and intended operating conditions.

IEC TS 62332-2:2014 is applicable to EIS containing solid and liquid components where the thermal stress is the dominant ageing factor, without restriction to voltage class. This part specifies a sealed tube test procedure for the thermal evaluation and qualification of electrical insulation systems (EIS). One aspect of this procedure is to also provide a method to assign thermal classifications to materials used in EIS where solid and liquid components are both used. This procedure describes a comparative ageing method whereby a reference system composed of kraft paper and mineral oil is compared to a candidate system of any combination of solid and insulating liquid. The test procedures in this part are specifically applicable to liquid immersed transformer insulation systems.

IEC 61858-1:2014 lists the required test procedures for qualification of modifications of an established electrical insulation system (EIS) with respect to its thermal classification. This standard is applicable to EIS used in wire-wound winding electrotechnical devices. The test procedures are comparative in that the performance of a candidate EIS is compared to that of a reference EIS, which has proven service experience in accordance with IEC 60505 or has been evaluated by one of the procedures given in the IEC 61857 series. This first edition of IEC 61858-1 cancels and replaces the third edition of IEC 61858, published in 2008. It constitutes a technical and editorial revision. This edition includes the following significant technical changes with respect to the previous edition:
a) this part is specifically for wire-wound winding EIS;
b) new figures and charts support the contents.

IEC 61858-2:2014 lists the required test procedures for qualification of modifications of an established electrical insulation system (EIS) with respect to its thermal classification. This standard is applicable to EIS used in form-wound electrotechnical devices. The test procedures are comparative in that the performance of a candidate EIS is compared to that of a reference EIS, which has proven service experience in accordance with IEC 60505 or has been evaluated by one of the procedures given in IEC 60085 and IEC 60034-18-31.

IEC 60505:2011 establishes the basis for estimating the ageing of electrical insulation systems (EIS) under conditions of either electrical, thermal, mechanical, environmental stresses or combinations of these (multifactor stresses). It specifies the principles and procedures that shall be followed, during the development of EIS functional test and evaluation procedures, to establish the estimated service life for a specific EIS. This standard should be used by all IEC technical committees responsible for equipment having an EIS. The contents of the corrigendum of March 2017 have been included in this copy.

IEC/TS 62332-1:2011(E) is applicable to EIS containing solid and liquid components where the thermal stress is the dominant ageing factor, without restriction to voltage class. This part specifies a dual-temperature test procedure for the thermal evaluation and qualification of electrical insulation systems (EIS). The following significant technical changes with respect to the previous edition have been made - Modifications have been made based on an extensive test series conducted using this methodology given in the first edition. This included updating expected times and tempertatures to use in order to obtain useful results, as well as making the range of equipment covered broader. The method can now cover electrotechnical devices using different sealing systems, as well as devices using enamel covered wires.

IEC 61857-21:2009 describes a general-purpose model (GPM) and a tall channel alternative model (GPM-TC) which can be used for the evaluation of wire-wound electrical insulation systems (EIS) where specific electrotechnical products are not available or required. The third edition cancels and replaces the second edition published in 2004, and constitutes editorial revisions to make this standard compatible with Parts 1 and 22.

IEC 61857-1:2008 specifies a general test procedure for the thermal evaluation and qualification of electrical insulation systems (EIS) and establishes a procedure that compares the performance of a candidate EIS to that of a reference EIS. This standard is applicable to existing or proposed EIS used in electrotechnical products with an input voltage of up to 1 000 V where the thermal factor is the dominating ageing factor. This third edition cancels and replaces the second edition published in 2004, and constitutes editorial revisions to make this standard compatible with Parts 21 and 22.

IEC 61857-22:2008 provides a general-purpose procedure for the evaluation of wire-wound systems using a general purpose encapsulated-coil model (ECM) where the application is unknown. This second edition cancels and replaces the first edition published in 2002, and constitutes editorial revisions to make this standard compatible with Parts 1 and 21.

IEC 60085:2007 now distinguishes between thermal classes for electrical insulation systems and electrical insulating materials. It establishes the criteria for evaluating the thermal endurance of either electrical insulating materials (EIM) or electrical insulation systems (EIS). It also establishes the procedure for assigning thermal classes. This standard is applicable where the thermal factor is the dominant ageing factor. The major technical changes with regard to the previous edition concern the fact that this edition is an amalgamation of the third edition of this standard together with IEC 62114:2001.

Applies to electrical insulation systems, specifies a short-time thermal and electrical evaluation procedure - applicable for devices with a supply voltage up to 1000 V (d.c./a.c./pulse), - using a wire-wound coil model; this model may be used for wire-wound applications, such as transformers, chokes, ballasts, reactors, ferrite converters, etc., - with minimum test life of 1500 h at the lowest ageing temperature, - for products that are not normally subjected to vibration. The model shall contain all components of the final product in order to determine chemical interaction under thermal ageing conditions. No modifications are allowed because this ageing program is designed to evaluate the entire EIS.