ASTM_D_5374_-_13.pdf

Designation:D537413Standard Test Methods forForced-Convection Laboratory Ovens for Evaluation ofElectrical Insulation1This standard is issued under the fixed designation D5374;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 These test methods cover procedures for evaluating thecharacteristics of forced-convection ventilated electrically-heated ovens,operating over all or part of the temperaturerange from 20C above the ambient temperature to 500C andused for thermal endurance evaluation of electrical insulatingmaterials.1.2 These test methods are based on IEC Publication 216-4-1,and are technically identical to it.This compilation of testmethods and an associated specification,D5423,have replacedSpecification D2436.1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D2436 Specification for Forced-Convection Laboratory Ov-ens for Electrical Insulation(Withdrawn 1994)3D5423 Specification for Forced-Convection Laboratory Ov-ens for Evaluation of Electrical Insulation2.2 Other Document:IEC Publication 216-4-1 Guide for the Determination ofThermal Endurance Properties of Electrical InsulatingMaterials,Part 4Aging Ovens,Section 1Single-Chamber Ovens43.Terminology3.1 Refer to the terminology section of SpecificationD5423.4.Significance and Use4.1 Ovens used for thermal evaluation of insulating materi-als are to be capable of maintaining uniform conditions oftemperature and air circulation over the extended periods oftime that are required for conducting these tests.SpecificationD5423 specifies the permissible deviations from absoluteuniformity that have been generally accepted internationallyfor these ovens.These test methods include procedures formeasuring these deviations and other specified characteristicsof the ovens.5.Apparatus5.1 Multi-Point Recording Potentiometer,having provisionsforatleastnineiron-constantanorchromel-alumelthermocouples,with scale readings to 0.1C or less.Use of adata processor or a data logger is helpful in reducing thenumber of calculations required.5.2 CalibratedIron-ConstantanorChromel-AlumelThermocouples,using 0.5-mm diameter or smaller wire andhaving a junction size not over 2.5 mm long.5.2.1If calibrated thermocouples are not available,usethermocouples made from a single spool of thermocouple wirethat gives values for temperature that do not differ from eachother by more than 0.2C when placed within 10 mm of eachother without touching inside an oven chamber at 200C.5.3 It is acceptable to use a temperature measuring systemother than thermocouples and a potentiometer,provided thatthe sensitivity,accuracy,and response time are equivalent tothat of the equipment described above,and that the objectivesof 6.2.3 relative to minimization of heat conduction effects aremet.5.4 Thermal Lag Time Specimen,consisting of a solid brasscylinder,10 mm in diameter and 55 mm long,with onejunction of a differential thermocouple soldered to the surfacemidway between the ends.The other junction of the thermo-couple must be capable of being moved at least 80 mm awayfrom the brass cylinder.An appropriate temperature indicator1These test methods are under the jurisdiction of ASTM Committee D09 onElectrical and Electronic Insulating Materials and are the direct responsibility ofSubcommittee D09.17 on Thermal Characteristics.Current edition approved Sept.1,2013.Published September 2013.Originallyapproved in 1993.Last previous edition approved in 2005 as D5374 93(2005).DOI:10.1520/D5374-13.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.4Available from American National Standards Institute(ANSI),25 W.43rd St.,4th Floor,New York,NY 10036.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1(as in 5.1,or other)must be provided for indication oftemperature differences to the nearest 0.1C as measured by thedifferential thermocouple.5.5 Watt-Hour Meter,of the appropriate voltage and phase,capable of reading to the nearest 1.0 Wh or less.6.Procedures6.1 Rate of Ventilation:6.1.1 Summary of Test MethodThe rate of ventilation iscalculated using determinations of(1)the average powerrequired to maintain the oven at a given temperature with itsports open and(2)the average power requi