1、CHECK THE MASTER LISTVERIFY THAT THIS IS THE CORRECT VERSION BEFORE USE National Aeronautics and MSFC-SPEC-494 Space Administration REVISION: B EFFECTIVE DATE: May 1, 2009 ES21 MULTIPROGRAM/PROJECT COMMON-USE DOCUMENT INSTALLATION OF HARNESS ASSEMBLIES (ELECTRICAL WIRING), SPACE VEHICLE, GENERAL SPE
2、CIFICATION FOR Approved for Public Release; Distribution is UnlimitedProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Multiprogram/Project Common-Use Document ES21 Title: Installation of Harness Assembly (Electrical Wiring), Space Vehicle, General Spe
3、cifications for Document No.: MSFC-SPEC-494 Revision: B Effective Date: May 1, 2009 Page 2 of 37 CHECK THE MASTER LISTVERIFY THAT THIS IS THE CORRECT VERSION BEFORE USE DOCUMENT HISTORY LOG Status (Baseline/ Revision/ Canceled) Document Revision Effective Date Description Baseline - 01/20/1971 Revis
4、ion A 04/20/1973 - Revision B 05/01/2009 Updated figures and nomenclature to reflect existing cable harness standards. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Multiprogram/Project Common-Use Document ES21 Title: Installation of Harness Assemb
5、ly (Electrical Wiring), Space Vehicle, General Specifications for Document No.: MSFC-SPEC-494 Revision: B Effective Date: May 1, 2009 Page 3 of 37 CHECK THE MASTER LISTVERIFY THAT THIS IS THE CORRECT VERSION BEFORE USE TABLE OF CONTENTS Paragraph Title Page 1 SCOPE 6 1.1 Scope . 6 1.2 EMC Classifica
6、tion . 6 1.3 Exceptions 6 1.4 Ordnance Cabling 6 2 APPLICABLE DOCUMENTS .7 2.1 Precedence .7 2.1.1 Specifications .7 2.1.1.1 Military 7 2.1.1.2 George C. Marshall Space Flight Center .7 2.1.1.3 NASA .7 2.1.1.4 Other Specifications .8 3 REQUIREMENTS .8 3.1 Selections of Specifications and Standards 8
7、 3.1.1 Contractors Specifications .8 3.2 Harness Assemblies .8 3.3 Installation Materials Selection 8 3.3.1 Metallic 8 3.3.2 Nonmetallic 8 3.3.3 Compatibility .8 3.3.4 Outgassing8 3.4 Reliability .8 3.5 Maintainability and Accessibility 9 3.6 Bend Radius and Folding Techniques .9 3.6.1 Optimum Bend
8、Radius .9 3.6.2 Minimum Bend Radius 9 3.6.2.1 Coaxial Cable .9 3.6.2.2 Wire Size Larger than 10 .9 3.6.2.3 Wire Size 10 or Smaller .11 3.6.2.4 Flexible Flat Conductor Cable Harness .11 3.6.2.5 Wires with Polyimide Insulation .11 3.7 Slack .15 3.7.1 Sharp or Rough Object Protection .16 3.7.2 Slack Be
9、tween Supports 16 3.7.2.1 Enclosed Harnesses 16 3.7.2.2 Other Harnesses .16 3.7.2.3 Flexible Flat Harnesses 16 3.8 Excess Length 16 3.9 Modifications .16 3.10 Protection .17 3.10.1 Moving Parts 17 3.10.2 Cushions and Grommets 17 Provided by IHSNot for ResaleNo reproduction or networking permitted wi
10、thout license from IHS-,-,-Multiprogram/Project Common-Use Document ES21 Title: Installation of Harness Assembly (Electrical Wiring), Space Vehicle, General Specifications for Document No.: MSFC-SPEC-494 Revision: B Effective Date: May 1, 2009 Page 4 of 37 CHECK THE MASTER LISTVERIFY THAT THIS IS TH
11、E CORRECT VERSION BEFORE USE 3.10.3 Protective Covering .18 3.10.4 Tape, Heat Shrinkable Boots, and Sleeving .18 3.10.4.1 Harness Overwrap 18 3.10.5 Harness Damage Prevention 18 3.11 Stowage 18 3.12 Prevention of Inadvertent Connector De-mate 18 3.13 Cleanliness .18 3.14 Harness Installation 18 3.14
12、.1 Routing of Similar Harnesses 18 3.14.2 EMC Classification / Separation Requirements 19 3.14.3 Cable Crossover .20 3.14.4 Applicable Harness Installation Drawings .20 3.14.5 Harness Routing .20 3.14.5.1 Routing Near Fluid and Gas Lines .20 3.14.6 Harness Support and Separation Clamps .20 3.14.6.1
13、Clamp Types 21 3.14.6.2 Clamp Size .26 3.14.6.3 Clamp Interval and Location .27 3.14.7 General Harness Installation 27 3.14.7.1 Harness Separation .28 3.14.7.2 Vibration and Movement .28 3.14.7.3 Stress 28 3.14.7.4 Abrasion Protection .28 3.14.7.5 Twisting Limit .28 3.14.7.6 Acceptance Test .28 3.14
14、.7.7 Unsupported Spans 28 3.14.8 Installation - Engine Area 28 3.14.9 Installation Fixed Components .28 3.14.10 Installation Moving Components 28 3.14.11 Connector Inspection Prior to Mating 29 3.14.11.1 Bent Connector Pins 33 3.14.11.2 Connector Soft Mate 33 3.14.12 Mismating of Connectors .33 3.14
15、.13 Torquing Connectors .33 3.14.14 Jam Nut Torque33 3.14.15 Electrical Bonding .33 3.14.16 Staking and Potting 33 3.14.17 Electrostatic Discharge Protection and Control .33 4 QUALITY ASSURANCE .35 4.1 Supplier Inspection 35 4.2 Tests .35 4.2.1 Testing After Rework / Repair .35 4.2.2 Test Equipment
16、Interfaces .35 4.3 Certification .35 4.4 Visual Inspection .35 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Multiprogram/Project Common-Use Document ES21 Title: Installation of Harness Assembly (Electrical Wiring), Space Vehicle, General Specifica
17、tions for Document No.: MSFC-SPEC-494 Revision: B Effective Date: May 1, 2009 Page 5 of 37 CHECK THE MASTER LISTVERIFY THAT THIS IS THE CORRECT VERSION BEFORE USE 5 NOTES .35 5.1 Intended Use 35 5.2 Ordering Date .35 6 DEFINITIONS .36 6.1 Coaxial Cable .36 6.2 Connector .36 6.3 Electrical Wire .36 6
18、.4 Electrical Harness Assembly .36 6.5 Electrical Cable 36 6.6 Flammable Material .36 6.7 Flat Conductor Cable .36 7 ACRONYMS AND ABBREVIATIONS 37 LIST OF TABLES Table Page I Minimum Bend Radius for Fluorocarbon Elastomer Convolute Tubing . 11 II Wiring Classification Separation Requirements . 19 II
19、I Bundle Size Factor 27 LIST OF FIGURES Figure Page 1 Harness Bend Radius 10 2 Bending and Folding Flexible Flat Conductor Cable Harnesses Direction and Polarity Change . 12 3 Bending and Folding Flexible Flat Conductor Cable Harnesses: Bending and Folding Sequence 13 4 Bending and Folding Flexible
20、Flat Conductor Cable Harnesses Branch Outs and Direction Change 14 5 Harness Slack Between Supports 15 6 Typical Direct Routing with Gentle Bends . 15 7 Examples of Grommets . 17 8 Examples of Harness with TFE and Fluorocarbon Tubing 21 9 Typical Support and Separation Clamp Types . 22 10 Typical Su
21、pport and Separation Clamp Types . 23 11 Typical Support and Separation Clamp Types . 24 12 Typical Support and Separation Clamp Types . 25 13 Typical Installation Methods for Flexible Flat Conductor Harnesses 29 14 Typical Installation Methods for Flexible Flat Conductor Harnesses 30 15 Typical Ins
22、tallation Methods for Flexible Flat Conductor Harnesses 31 16 Typical Installation Methods for Flexible Flat Conductor Harnesses 32 17 Examples of Termination of Ground Wire to Structure . 34 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Multiprogr
23、am/Project Common-Use Document ES21 Title: Installation of Harness Assembly (Electrical Wiring), Space Vehicle, General Specifications for Document No.: MSFC-SPEC-494 Revision: B Effective Date: May 1, 2009 Page 6 of 37 CHECK THE MASTER LISTVERIFY THAT THIS IS THE CORRECT VERSION BEFORE USE 1. SCOPE
24、 1.1 Scope. This specification establishes requirements for the design of installation and the actual installation of electrical harness assemblies in space vehicles and payloads. 1.2 Electromagnetic Compatibility (EMC) Classification. Harness assemblies used to interconnect electrical and/or electr
25、onic assemblies (excluding printed circuitry and internal black boxes) are classified as follows: 1.2.1 Class ML - Low-level analog or sensitive circuit designation 1.2.2 Class HO - Control and high-level discrete signal circuit Designation 1.2.3 Class EO - Power and high voltage (40 V) circuit desi
26、gnation 1.2.4 Class RF - Radio Frequency 1.2.5 Class MO - Pyrotechnic Circuit designation 1.2.6 Class FO - Fiber Optic 1.3 Exceptions - This document does not apply to installation of fiber optic (Class FO) or rigid coax cable assemblies. 1.4 Ordnance Cabling. Routing and installation of ordnance ha
27、rnesses shall meet the requirements of MIL-STD-1576, Electroexplosive Subsystem Safety Requirements and Test Methods for Space Systems. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Multiprogram/Project Common-Use Document ES21 Title: Installation
28、of Harness Assembly (Electrical Wiring), Space Vehicle, General Specifications for Document No.: MSFC-SPEC-494 Revision: B Effective Date: May 1, 2009 Page 7 of 37 CHECK THE MASTER LISTVERIFY THAT THIS IS THE CORRECT VERSION BEFORE USE 2. APPLICABLE DOCUMENTS 2.1 Precedence - The following documents
29、 form a part of this specification to the extent specified herein. Unless otherwise indicated, the issue in effect on date of invitation for bids or request for proposals shall apply. When requirements of this specification and the requirements of any applicable document conflict, the requirements o
30、f this specification shall take precedence. 2.1.1 SPECIFICATIONS 2.1.1.1 Military MIL-STD-889 Dissimilar Metals MIL-STD-1576 Electroexplosive Subsystem Safety Requirements and Test Methods for Space Systems 2.1.1.2 George C. Marshall Space Flight Center MSFC-SPEC-106 Testing Compatibility of Materia
31、ls for Liquid Oxygen Systems MSFC-SPEC-250 Protective Finishes for Space Vehicle Structures and Associated Flight Equipment, General Specifications for MSFC-50M02442 Material Control for Contamination Due to Outgassing MSFC-SPEC-522 Design Criteria for Controlling Stress Corrosion Cracking 2.1.1.3 N
32、ASA NASA-STD-3000, Vol. 1 Man Systems Integration Standards NASA-STD-6001 Flammability, Odor, Offgassing and Compatibility Requirements and Test Procedures For Materials in Environments that Support Combustion. NASA-STD-8739.1 Workmanship Standard for Staking and Conformal Coating of Printed Wiring
33、Boards and Electronic Assemblies. NASA-STD-8739.4 Crimping, Interconnecting Cable Harness and Wirng NASA-STD-4003 Electrical Bonding for NASA Launch Vehicles, Spacecraft, Payloads and Flight Equipment Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-M
34、ultiprogram/Project Common-Use Document ES21 Title: Installation of Harness Assembly (Electrical Wiring), Space Vehicle, General Specifications for Document No.: MSFC-SPEC-494 Revision: B Effective Date: May 1, 2009 Page 8 of 37 CHECK THE MASTER LISTVERIFY THAT THIS IS THE CORRECT VERSION BEFORE USE
35、 2.1.1.4 Other Specifications EOS / ESD S20.20. For the Development of an Electrostatic Discharge Control Program for- Protection of Electrical and Electronic Parts, Assemblies, and Equipment 3. REQUIREMENTS 3.1 Selection of Specifications and Standards. Technical specifications required for install
36、ation and inspection not identified in this specification shall be selected in accordance with the order of precedence specified in NASA-STD-8739.4, except that approved and coordinated Government procuring activity specifications shall be first in the order of precedence. 3.1.1 Contractors Specific
37、ations. Contractors specifications may be used provided no higher precedence specification exists and provided the contractors specification is approved by the procuring activity. 3.2 Harness Assemblies. Unless otherwise specified or approved by the Government procuring activity, harness assemblies
38、will conform to the requirements of NASA-STD-8739.4. 3.3 Installation Materials Selection. 3.3.1 Metallic. Metallic materials shall be selected and used in accordance with MIL-STD-889 and MSFC-SPEC-522 to reduce corrosion and stress corrosion. Protective finishes shall conform to MSFC-SPEC-250 as mo
39、dified by NASA-STD-6001 and MSFC-SPEC-106. 3.3.2 Nonmetallic. Prior to installation, nonmetallic materials used in installation shall be approved for the predicted environments. Nonmetallic materials for use in inhabited or oxygen enriched areas shall be approved in accordance with NASA-STD-6001. 3.
40、3.3 Compatibility. Materials for subsequent installation within Liquid Oxygen (LOX) environments shall be LOX compatible in accordance with MSFC-SPEC-106. Materials for subsequent installation within liquid hydrogen, vacuum, radiation, and other extreme environments shall be qualified to requirement
41、s specified by the procuring activity and approved by the Government procuring activity. 3.3.4 Outgassing. Materials used for installation of harness assemblies (wiring) shall be selected from the approved listing per MSFC-50M02442 or shall be approved in accordance with the outgassing requirements
42、of NASA-STD-6001. 3.4 Reliability. Electrical installation hardware shall be such that established vehicle or equipment reliability figures are not degraded. 3.5 Maintainability and Accessibility. Maintainability and accessibility for servicing and repair of parts, components, and subsystems shall m
43、eet the requirements of NASA-STD-3000. 3.6 Bend Radius and Folding Techniques. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Multiprogram/Project Common-Use Document ES21 Title: Installation of Harness Assembly (Electrical Wiring), Space Vehicle, G
44、eneral Specifications for Document No.: MSFC-SPEC-494 Revision: B Effective Date: May 1, 2009 Page 9 of 37 CHECK THE MASTER LISTVERIFY THAT THIS IS THE CORRECT VERSION BEFORE USE 3.6.1 Optimum Bend Radius. Bends in all cable harness classifications should approach 10 times the harness diameter. See
45、Figure 1 for measurement of bend radius. 3.6.2 Minimum Bend Radius. 3.6.2.1 Coaxial Cable. The minimum bend radius for coaxial radio frequency cable or harness assemblies containing such cable shall not be less than six (6) times the cable or harness diameter. 3.6.2.2 Wire Size Larger than 10. The m
46、inimum bend radius for harness assemblies containing wire larger than size 10 shall not be less than six (6) times the harness diameter. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Multiprogram/Project Common-Use Document ES21 Title: Installation
47、 of Harness Assembly (Electrical Wiring), Space Vehicle, General Specifications for Document No.: MSFC-SPEC-494 Revision: B Effective Date: May 1, 2009 Page 10 of 37 CHECK THE MASTER LISTVERIFY THAT THIS IS THE CORRECT VERSION BEFORE USE Figure 1. Harness Bend Radius Provided by IHSNot for ResaleNo
48、reproduction or networking permitted without license from IHS-,-,-Multiprogram/Project Common-Use Document ES21 Title: Installation of Harness Assembly (Electrical Wiring), Space Vehicle, General Specifications for Document No.: MSFC-SPEC-494 Revision: B Effective Date: May 1, 2009 Page 11 of 37 CHECK THE MASTER LISTVERIFY THAT THIS IS THE CORRECT VERSION BEFORE USE 3.6.2.3 Wire Size 10 or Smaller. The minimum bend radius for harness assemblies containing only wire size 10 or smaller shall not be less than three (3)
