1、NOTE: MIL-STD-2141(SH) has been redesignated as a handbook, and is to be usedfor guidance only. This document is no longer to be cited as a requirement.For administrative expediency, the only physical change from MIL-STD-2141(SH)is this cover page. If cited as a requirement, contractors may disregar
2、d therequirements of this document and interpret its contents only as guidance.METRICMIL-HDBK-2141(SH)1 JUNE 1983AMSC N/A FSC 1905DISTRIBUTION STATEMENT A. Approved for public release; distribution isunlimited.DEPARTMENT OF DEFENSEMILITARY HANDBOOKDEFINITIONS AND SYSTEMS OF UNITS,MAGNETIC SILENCING
3、(METRIC)Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-DEPARTMENT OF THE NAVYNAVAL SEA SYSTEMS COMMANDWashington, DC 20362Definitions and Systems of Units, Magnetic Silencing (Metric).DOD-STD-2141(SH)1. This Military Standard is approved for use by th
4、e Naval Sea SystemsCommand, Department of the Navy, and is available for use by all Departmentsand Agencies of the Department of Defense.2. Beneficial comments (recommendations, additions, deletions) and anypertinent data which may be of use in improving this document should beaddressed to: Commande
5、r, Naval Sea Systems Command, SEA 5523, Departmentof the Navy, Washington, DC 20362 by using the self-addressed StandardizationDocument Improvement Proposal (DD Form 1426) appearing at the end of thisdocument or by letter.Provided by IHSNot for ResaleNo reproduction or networking permitted without l
6、icense from IHS-,-DOD-STD-2141(SH)1 June 1983FOREWORD1. The application of magnetic silencing requirements for nonmagneticmine warfare ships and craft requires the establishment of a method of communi-cation to ensure that coordinated thinking is applied. Key words and termsmore commonly used are de
7、fined in this standard, The standard also states thesystems of units which are used.2. The user of this document may wish to consult commercial standards,such as ASTM A 340 for definitions beyond those included in this standard.iiiProvided by IHSNot for ResaleNo reproduction or networking permitted
8、without license from IHS-,-Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-Provided by IHSNot for ResaleNo reproduction or networking permitted without lice
9、nse from IHS-,-Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-DOD-STD-2141(SH)1 June 19831. SCOPE1.1 scope. This standard contains definition, abbreviation
10、s, acronyms,units and symbols used in magnetic silencing. Definitions of abbreviationsand terms are limited to statements of meaning as related to this and referencedstandards, rather than encyclopedia or textbook discussions.2. REFERENCED DOCUMENTS2.1 Other publications. The following documents for
11、m a part of thisstandard to the extent specified herein. Unless otherwise indicated, the issuein effect on date of invitation for bids or request for proposal shall apply.AMERICAN SOCIETY FOR TESTING AND MATERIALS (ASTM)A 340 - Terms, Symbols, and Conversion Factors Relatingto Magnetic Testing.E 380
12、 - Standard for Metric Practice.(Application for copies should be addressed to the American Societyfor Testing and Materials, 1916 Race Street, Philadelphia, PA 19103.)INSTITUTE OF ELECTRICAL AND ELECTRONICS ENGINEERS (IEEE)IEEE 268 - Metric Practices.(Application for copies should be addressed to t
13、he Institute of Electricaland Electronics Engineers, 345 East 47th Street, New York, NY 10017.)(Technical society and technical association specifications and standardsare generally available for reference from libraries. They are also distributedamong technical groups and using Federal agencies.)3*
14、 DEFINITIONS3.1 Applicability of definitions. The following definitions and termsapply to the restricted field of magnetic silencing for nonmagnetic mine warfareships and craft. To the extent possible, these definitions are in agreementwith those of ASTM A 340.3.1.1 Air-gap magnetizing force. Air-ga
15、p magnetizing force is the magnet-izing force required to produce the induction existing at some point in a non-magnetic gap in a magnetic circuit (Hg). In the cgs system, H8 is numericallyequal to the induction existing at such a point and exceeds the magnetizingforce in the magnetic material.3.1.2
16、 Ampere-turn. Ampere-turn is a unit of magnetomotive force in SI.One ampere-turn equals 4/10 or 1.257 gilberts.3.1.3 Ampere-turn per meter. Ampere-turn per meter is a unit of magnet-izing force (magnetic field strength) in SI. One ampere-turn per meter is4 x 10-3 or 0.01257 oersted.1Provided by IHSN
17、ot for ResaleNo reproduction or networking permitted without license from IHS-,-DOD-STD-2141(SH)1 June 19833.1.4 Anisotropic material. Anisotropic material is a material in whichthe magnetic properties differ in various directions.3.1.5 Antiferromagnetic material. Antiferromagnetic material is feebl
18、ymagnetic material in which almost equal magnetic moments are lined up anti-parallel to each other. Its susceptibility increases as the temperature israised until a critical (Neel) temperature is reached; above this temperaturethe material becomes paramagnetic.3.1.6 Area. Area is the geometric regio
19、n encompassed by a magnetic path,an electric path or a physical boundary. An area may be a limiting area (see3.1.71), a surface area (A) or a cross-sectional area (a or A).3.1.7 Calibration. Calibration is the adjustment of the means of magneticfield compensation installed aboard ship to provide an
20、optimum magnetic fieldcompensation.3.1.8 Calibration limit. Calibration limit is the maximum acceptablelimit for a magnetic field or a single component of a magnetic field, from agiven source or combination of sources, placed on the peak value of the fieldor component at the end of calibration, in o
21、rder that the corresponding fieldor component maintenance will not be exceeded during the subsequent periodof operations.3.1.9 Cgs-em system of units. Cgs-em system of units is a former systemfor measuring physical quantities in which the basic units are the centimeter,gram, and second (cgs), and th
22、e numerical value of the magnetic constant, Im,is unity.3.1.10 Coercive force. Coercive force is the magnetizing force at whichthe magnetic flux density is zero when the material is in a symmetrically cycli-cally magnetized condition (HC).3.1.11 Coercive force, intrinsic. Intrinsic coercive force is
23、 themagnetizing force at which the intrinsic induction is zero when the materialis in a symmetrically cyclically magnetized condition (HC1).3.1.12 Coercivity. Coercivity is the maximum value of coercive force (HC8)C3.1.13 Combined magnetic field. Combined magnetic field is the magneticfield which is
24、 the sum of the magnetic fields due to two or more sources, suchas the normal and roll fields. When applied to ship fields, combined field isassumed to mean the field due to all sources on board or towed by the ship,unless the field is explicitly otherwise defined (except that the magneticsweep fiel
25、d and the fields due to minesweep winch circuits and circuits usedonly momentarily are not included).3.1.14 Craft. A craft is a water surface vehicle with a hull, which hasa beam equal to or less than 4.5 meters.3.1.15 Curie temperature. Curie temperature is the temperature abovewhich a ferromagneti
26、c material becomes paramagnetic (TC).Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-DOD-STD-2141(SH)1 June 19833.1.16 Cyclically magnetized condition. Cyclically magnetized condition isa magnetic material in a cyclically magnetized condition (CM) when
27、, after havingbeen subjected to a sufficient number of identical cycles of magnetizing force,it follows identical hysteresis or flux-current loops on successive cycleswhich are not symmetrical with respect to the origin of the axes.3.1.17 Degaussing coil. Degaussing coil is a system of electric curr
28、entloops used to neutralize a component of magnetization. The principal typesof degaussing coils are as follows:(a) M-coil: M-coil is a horizontal coil used to neutralize verticalmagnetization.(b) A-coil: A-coil is a coil with loops in vertical fore and aftplanes used to neutralize athwartship magne
29、tization.(c) L-coil: L-coil is a series of loops generally extending from bowto stern, each loop being in a vertical athwartship plane, usedto neutralize longitudinal magnetization.3.1.18 Degaussing coordinate system. The degaussing coordinate systemrelative to a ship is defined as follows:(a) Longi
30、tudinal (fore-and-aft), athwartship, and vertical directionsand distances are used. When these are described by letters, theletters are respectively: x, positive forward; y, positive toport; and z, positive downward. This is a left-handed system.(b) The fore-and-aft, athwartship, and vertical distan
31、ces are measuredfrom the extreme bow, centerline, and full-load waterline of theship, respectively. The vertical distance is often called thedepth.3.1.19 Demagnetization curve. Demagnetization curve is that portion ofa normal hysteresis loop which lies in the second or fourth quadrant; that is,betwe
32、en the residual induction point, Br, and the coercive force point, HC.Points on this curve are designated by the coordinates, Bd and Hd.3.1.20 Demagnetizing coefficient. The demagnetizing coefficient (DB) isdefined by the equation:where:Ha = applied magnetizing force,H = magnetizing force actually e
33、xisting in themagnetic material, andrm = 1 in the cgs system and 4 x 10-7 henry/meterin SI (rationalized).For a closed, uniform magnetic circuit the demagnetizing coefficientis zero.3Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-DOD-STD-2141(SH)1 Jun
34、e 19833.1.21 Demagnetizing factor. The demagnetizing factor (ND) is defined as4 times the demagnetizing coefficient, DB.3.1.22 Demagnetizing force. Demagnetizing force is a magnetizing force(on the demagnetization curve) applied in such a direction as to reduce theinduction in a magnetized body (Hal
35、). See demagnetization curve (3.1.19).3.1.23 Density. Density is the ratio of the mass to the volume of amaterial, kg/m3 or g/cm3 (6).3.1.24 Diamagnetic material. Diamagnetic material is material whoserelative permeability is less than unity. The intrinsic induction, Bi, isoppositely directed to the
36、 applied magnetizing force H.3.regionsrials.times ,1.2, eEaand5 Domains, ferromagnetic. Domaither macroscopic or microscopicch domain, per se, is magnetizedthis saturation induction is unins,intoidirferromagnesize, withiintrinsic sectional witic are magnetizedn ferromagnetic mate-aturation at allthi
37、n the domain.3.1.26 Eddy current field. Eddy current field is the magnetic field dueto the eddy currents induced in the conducting material of or on the ship bythe rolling motion of the ship in the earths magnetic field.3.1.27 Eddy current source. Eddy current source is any item which containselectr
38、ically continuous loops of electrically conductive material.3.1.28 Eddy currents. Eddy currents are the electrical currents inducedin a shipboard material as the result of the ship rolling and pitching in theearths magnetic field.3.1.29 Electrical circuit (circuitry). Electrical circuit or circuitry
39、refers to all electrical equipment and interconnecting wires and cables.3.1.30 Electrical conductivity, percent. Percent electrical conductivityrefers to the percent of electrical conductivity of a material relative to theelectrical conductivity of copper at the same temperature (c).3.1.31 Electrica
40、l conductivity of copper. The electrical conductivityof copper at 20 degrees Celsius (C) is 5.8 x 105 siemens per meter (S/m).Copper resistivity (inverse of conductivity) at the same temperature is1.7241 X 10-6 ohm . m.3.1.32 Electrical conductor. Electrical conductor is a wire, cable orbusbar used
41、to allow electricity to flow from one point to another point.3.1.33 Electrical steel. Electrical steel is a term used commerciallyt0 designate a flatrolled iron-silicon alloy used for its magnetic properties.3.1.34 Electrically conductive material. Electrically conductive materialrefers to material
42、whose electrical conductivity is greater than or equal to0.5 percent of the electrical conductivity of copper.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-DOD-STD-2141(SH)1 June 19833.1.35 Electrically continuous path. Electrically continuous path i
43、s apath of electrically conductive material not containing a resistive element.3.1.36 Electrically continuous surface. Electrically continuous surface isa surface of electrically conductive material not containing a resistive element.3.1.37 Equipment. Equipment comprises materials, fittings, devices
44、,appliances, fixtures, apparatus, machines, components, systems, and so forthused as part of or in connection with Navy ships.3.1.38 Fabrication. Fabrication is any type of manipulation of a materialto shape it into a required configuration. .3.1.39 Feebly magnetic material. Feebly magnetic material
45、 is a materialgenerally classified as nonmagnetic and whose maximum normal permeability is2.0 or less.3.1.40 Ferromagnetic material. Ferromagnetic material is material inwhich unequal magnetic moments are lined up antiparallel to each other, Per-meabilities are of the same order of magnitude as thos
46、e of ferromagnetic mate-rials, but are lower than they would be if all atomic moments were parallel andin the same direction. Under ordinary conditions the magnetic characteristicsof ferromagnetic materials are quite similar to those of ferromagnetic materials,3.1.41 Ferromagnetic field. Ferromagnet
47、ic field refers to the magneticfield due to all ferromagnetic materials of and in the ship, including anystores aboard and any sweep gear aboard or streamed, while the ship is notrolling or pitching. It does not include the field of ferromagnetic materialswhile magnetized specifically for producing
48、a ferromagnetic sweep field.3.1.42 Ferromagnetic material. Ferromagnetic material refers to a materialthat, in general, exhibits the phenomena of hysteresis and saturation, and Itspermeability is dependent on the magnetizing force.3.1.43 Ferrous magnetic field. Ferrous magnetic field is the magneticfield of a material which consists of the permanent magnetic field plus theinduced magnetic field.3.1.44 Ferrous source. Ferrous source is any material that generates aferrous magnetic field.3.1.45 Flux path length. Flux path length refers to the distance alonga flux loop 3.1.46 Gauss
