IEEE 638-2013 pdf free.IEEE Standard for Qualification of Class 1 E Transformers for Nuclear Power Generating Stations.
Transformer tests are conducted as combinations of ‘routine” and “design” tests, as described in Clause 6. These tests are defined in IEEE SW C57.12.8O, and requirements and test procedures are described in IEEE Std C57.12.OO. IEEE Std C57.12.Ol, IEEE Std C57.12.90, IEEE Std C57.l2.91, and IEEE Std 344. Successful completion of these tests and specified acceptance criteria, as defined in the above-referenced standards, is required for qualification, thus demonstrating that the transformer is capable of meeting the performance requirements in the user’s specification.
5.3 Thermal life qualification
When thermal aging effects based on qualified life of insulation and support systems have been demonstrated to be negligible, seismic tests may be performed without prior thermal aging.
When thermal aging effects based on qualified life cannot be demonstrated to be negligible, then thermal aging of the transformer under qualification shall be performed prior to seismic testing of the referenced transformer. The following approach may be used to evaluate the thermal life of the transformer.
Due to limitations related to physical size, energy requirements, and elapsed time, thermal aging of a complete transformer may not be practical. Also, because of the probable inability of thermal aging procedures to condition a complete transformer to a known end of qualified life, attempting to thermally age a complete transformer prior to qualification testing is most likely not practical. Therefore, in lieu of thermally aging a complete transformer, it is acceptable to thermally age windings. components, or valid insulation system models and materials (accurately representing transformer designs to be qualified) to determine the thermal effects expected to accrue during the transformer’s operating life.
Acceptable aging procedures and end-point testing are outlined in IEEE Std C57.l2.60 or IEEE Std (‘57.100. Other thermal aging procedures may be used provided that justification is agreed upon between manufacturer and user. The data used to support the thermal aging procedures shall be pertinent to the application and shall be available in an auditable form.
5.4 Thermal analysis calculation
Transformer loading guides IEEE Std C57.91 and IEEE SW C57.96 include procedures for calculating conservative estimates of the fraction of transformer life expectancy that is expended under various temperature andior loading conditions. Operation of a transformer at less than the rated insulation system temperature will reduce aging of the insulation system during its design life, as shown in the above- referenced loading guides. The effects of nonsiniisoidal loading, if applicable, should be accounted for in the thermal analysis calculations. IEEE Std C57.l 10 includes procedures for calculating the effects of nonsinusoidal loading on a transformer’s loading capability. When a thermal analysis calculation is peribrmed. the above-referenced standards and guides that are applicable for the particular transformer being qualified shall he utilized.
5.5 OperatIng experience
Operating experience documentation of 40 years or more may be available. however, detailed auditable data to support the actual transformer load profile is usually not available. To establish qualification by operating experience, consideration of the following factors is useful.
a) The same basic design and insulation system shall have been utilized.
b) Auditable records by expert engineers (such as those responsible for the design or the resolution of field problems) concerning the difficulties (or lack thereof) experienced with the generic design family under consideration shall be utilized.
c) Actual users’ records documenting the environmental, seismic and electrical loading conditions shall be included in the report.
5.6 Qualification by analysis and test
Quahitication by analysis and test shall be accomplished utilizing techniques such as the tohlowing:
a) When analytical modeling is used to demonstrate the performance behavior, the model shall yield calculated values that are within 10% of tested values for the same parameters. Thc source for component performance data should be reported. The analytical model should be available for third-party review as well as the assumptions. test data, conditions, and accepted industry practices.
b) Physical, chemical, and engineering data may be utilized to predict the perlormanec of transformers or components thereof.
c) Where appropriate, and to avoid repeating tests, data obtained from technical literature surveys may be used to demonstrate anticipated performance of materials when the source references are available to the public and when actual test data support the literature.
d) The data used to Support qualification by analysis shall be pertinent to the application and shall be available in an auditablc form.IEEE 638 pdf free download.