Calibrations of voltage transformer comparators are handled on ial test basis; however, advance arrangements need not be made. 064 a Calibration of kilovoltmeters at five scale points on one range 064b 064 c 064d Calibration of kilovoltmeters at five scale points on one Calibration of each additional scale point on one of the range kV). to 60 ranges 311.001 Dielectric constant and dissipation factor. In general, the Bureau will make tests of insulating and dieric properties of materials only only on (1) specimens of known compoon of pure materials for which values are considered of of use by the au or by other government agencies, and (2) dielectric reference dards made from materials exhibiting reproducible behavior under speciI environmental conditions (such as humidity), when such standards are ed for improving methods of measurement. Measurements are not made on effective insulation resistances, dielectric constant, or dissipation or of structures and assemblies of insulation, or on electric breakdown rally. Inquiries giving comprehensive information regarding any tests red from low frequencies up to 30 kHz should should be directed to the onal Bureau of Standards, Washington, DC 20234. Inquiries concerning s above 30 kHz should be addressed to the National Bureau of Standards, der, Colorado 80302. NBS, Washington, has a limited number of low loss ectric reference specimens available for loan for standardization oses in either frequency range. The conditions of loan and the fee be determined at the time of application. 313.000 General. (a) Direct inquiries to, and mark shipments for the attenti A127, National Bureau of: Magnetic Measurements Section, MET (b) A general discussion of magnetic principles and methods us in magnetic testing is given in NBS Monograph 47, "Basic Magnet Quantities and the Measurement of the Magnetic Properties of Materials available from Superintendent of Documents, U. S. Government Printi Office, Washington, DC 20402, price 30 cents. (c) Tests in this field for the most part are made on sampl which serve as standards to coordinate work in various laboratories a thus secure uniformity in commercial testing. For this purpose it essential that the standard bars be very very uniform in their magnet properties. Normally, the Bureau does not make routine acceptance tests magnetic materials unless these these specimens are to be used, at lea temporarily, as standards. The standard dimensions of magnetic te specimens are given in 313.001 and 313.002 Occasionally, it is possible test specimens of unusual materials or shapes where the services of t Bureau are needed in the development of new test procedures which a likely to be of importance in the industry. In such cases a fu understanding of the problem should be developed by correspondence, preferably by a visit, which will permit direct discussion between t engineers concerned and the Bureau staff. 313.001 Normal induction and hysteresis. Specimens submitted for test should be of rectangular cro section, width not to exceed 3.0 cm (1 1/8 in.), thickness not to exce 1.0 cm (3/8 in.); for magnetizing forces from 0 to 300 or 0 to 5,0 oersteds (0e), length to be not less than 25.4 cm (10 in.); for magnetizi forces in the range 100 to 5,000 Oe, length to be not less than 7 cm (2 5 in.). Specimens whose permeability is not greater than 4 may be circular cross section, diameter not to exceed 1.27 cm (1/2 in.), but any event cross-sectional area must be not less than 0.2 cm2 (0.031 in. 2 ) 313.001a 313.00 1b 313.001c 313.001d 313.001e Determination of data for normal induction curve in the range to 300 Oe. Determination of data for normal induction curve in the range 1 to 5,000 Oe. Determination of data for normal induction curve in the range to 5,000 Oe. Determination of data for demagnetization curve, one value Same as 313.001d, each additional value of maximum magnetiz force. 3.001f Determination of permeability for specimens whose permeability is less than 4, first specimen. 3.001g 3.001z Each additional specimen submitted at the same time. Special measurements not covered by this schedule. 313.002 Magnetic materials: a-c permeability and core loss. Test specimens should consist of the proper number of strips 3 cm 3/16 in.) wide and either 28 cm (11 1/82 in.) to 30.5 cm (12 in.) or 50 (19 11/16 in.) long, prepared in accordance with the specifications of e American Society for Testing and Materials, A-34. Item 3.002a Description Determination of total core loss at 60 Hz (c/s) at one value of maximum induction. 3.002b 3.002c Same as 313.002a, each additional value of maximum induction. Determination of a-c permeability at 60 Hz at one value 3.002d Same as 313.002c, each additional value of maximum induction. of Examination of material found to be unsuitable for measurement or special measurements not covered by this schedule. 313.003 Magnetic testing apparatus: Mutual inductors, ils, fluxmeters, solenoids, Helmholtz coils, and standard magnets. search Item Description 3.003a Determination of mutual induction by direct current. 3.003b 3.003c same Same as 313.003a, each additional inductor submitted at the Determination of the area- turns of a search coil, first coil. 3.003d Each additional search coil submitted at the same time. 3.003e 3.003f Calibration of fluxmeter at not more than five points on one range. Calibration of fluxmeter at one scale point on an additional range. 313.00 3h Direct current calibration of solenoids and Helmholtz coils. 313.003z Examination of apparatus unsuitable for measurement or spec |