IEC 61857-31:2017 pdf download

IEC 61857-31:2017 pdf download.Electrical insulation systems – Procedures for thermal evaluation – Part 31: Applications with a designed life of 5 000 h or less
1 Scope
This part of IEC 61 857 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.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements 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 60505, Evaluation and qualification of electrical insulation systems IEC 61 857-1 , Electrical insulation systems – Procedures for thermal evaluation – Part 1: General requirements – Low-voltage IEC TR 61 857-2, Electrical insulation systems – Procedures for thermal evaluation – Part 2: Selection of the appropriate test method for evaluation and classification of electrical insulation systems IEC 61 857-21 , Electrical insulation systems – Procedures for thermal evaluation – Part 21: Specific requirements for general-purpose models – Wire-wound applications IEC 61 857-22, Electrical insulation systems – Procedures for thermal evaluation – Part 22: Specific requirements for encapsulated-coil model – Wire-wound electrical insulation system (EIS)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 61 857-1 and the following apply. ISO and IEC maintain terminological databases for use in standardization at the following addresses: • IEC Electropedia: available at http://www.electropedia.org/ • ISO Online browsing platform: available at http://www.iso.org/obp 3.1 designed life expected application time which is proposed or decided by an end user, an industrial manufacturer, etc., regardless of the duty cycle, continual or intermittent
4 EIS evaluation
Procedure A (see Clause 6) is intended for EIS with a designed life of 1 500 h or less, subjecting one set of test objects to one-temperature ageing at 1 0 K above the maximum design temperature. The average life of the set under evaluation shall be at least 1 500 h. Procedure B (see Clause 6) is intended for EIS with a designed life of 5 000 h or less, subjecting one set of test objects to one-temperature ageing at 1 0 K above the maximum design temperature. The ageing time in Procedure A may be increased up to 5 000 h to correspond to the designed life of the EIS. The average life of the set under evaluation shall be at least 1 500 h. Procedure C (see Clause 6) is intended for EIS with a designed life of 5 000 h or less, subjecting two sets of test objects to two-temperature ageing at 20 K to 30 K and 30 K to 35 K above the maximum design temperature. The test results determined by either Procedure A, Procedure B or Procedure C described in Clause 6 can be expanded to larger full thermal evaluations in accordance with IEC 61 857 (all parts), if the additional thermal ageing is started prior to the completion of the thermal ageing according to this document. When expanded to a full thermal ageing, the work undertaken according to this document is referred to as a screening test portion of the full thermal ageing. Also, IEC 61 857-1 and IEC TR 61 857-2 may require a reference EIS to be included in the evaluation for establishing a relative thermal endurance (RTE) rating. When expansion is needed, an evaluation with regard to other applications shall require the addition of a reference EIS in accordance with an EIS method selected from IEC TR 61 857-2.
The average life of the set under evaluation shall be at least 1 500 h. To accumulate at least 1 500 h prior to the breakdown of the EIS the ageing cycle shall be 1 68 h. NOTE 1 68 hours (one week) is used for accumulating more than 1 500 ageing hours in nine ageing cycles. If the set of test objects exceeds the original test time of 1 500 h the test may be terminated as the target was achieved or the thermal ageing may be continued to achieve an expanded goal. 6.2 Procedure B: Establishing a TE rating for applications with a designed life of 5 000 h or less: one-temperature ageing The one-temperature ageing described in Procedure A can be extended to accumulate additional hours. The set undergoing thermal evaluation under Procedure A can be extended to a time coordinate of up to 5 000 h.