KSC-STD-E-0002 REV E-2009 HAZARDPROOFING OF ELECTRICALLY ENERGIZED EQUIPMENT STANDARD FOR《通电设备危害的防护标准》.pdf

1、KSC-STD-E-0002E MARCH 12, 2009 Supersedes KSC-STD-E-0002D June 11, 2007 HAZARDPROOFING OF ELECTRICALLY ENERGIZED EQUIPMENT, STANDARD FOR EAR 99 NO LICENSE REQUIRED The information contained in the document is technical in content, but not technical data as defined by the International Traffic in Arm

2、s Regulations (ITAR) or the Export Administration Regulations (EAR), and therefore is EAR 99 NLR, no export license required, suitable for public release. General Prohibition Six (Embargo) applies to all items subject to the EAR, i.e. items on the CCL and within EAR 99 NLR. You may not make an expor

3、t or re-export contrary to the provisions of part 746 (Embargos and Other Special Controls) of the EAR and 22 CFR part 126.1 of the ITAR. KSC EDDR #09186 ENGINEERING DIRECTORATENational Aeronautics and Space Administration John F. Kennedy Space Center KSC FORM 16-12 (REV. 6/95) PREVIOUS EDITIONS ARE

4、 OBSOLETE (CG 11/95) 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-,-,-KSC-STD-E-0002E MARCH 12, 2009 Supersedes KSC-STD-E-0002D June 11, 2007 KSC Form 7-

5、657 NS (01/09) 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 license from

6、 IHS-,-,-Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-KSC-STD-E-0002E March 12, 2009 CONTENTS 1. PURPOSE AND SCOPE.1 2. APPLICABLE DOCUMENTS .1 2.1 Governmental.1 2.1.1 Specifications.1 2.1.2 Standards2 2.1.3 Handbooks .2 2.2 Nongovernmental.2 2.3

7、 Order of Precedence.3 3. DEFINITIONS.3 4. GENERAL REQUIREMENTS.4 5. GUIDELINES4 5.1 Hazardous Locations and Classifications 4 5.2 Purging and Pressurizing .5 5.3 Equipment for Hazardous Areas6 5.3.1 Class and Properties.6 5.3.2 Cable Wiring Methods.6 5.4 Electrical Connections for Meters, Instrumen

8、ts, and Relays.8 6. QUALITY ASSURANCE PROVISIONS 8 7. PREPARATION FOR DELIVERY 8 8. NOTES.9 8.1 Intended Use 9 8.2 Notice.9 APPENDIX A. SPACE SHUTTLE ELECTRICAL-POWER HAZARDOUS-ZONE DOCUMENTATION 11 KSC-STD-E-0002E_DD_03122009.doc iii Provided by IHSNot for ResaleNo reproduction or networking permit

9、ted without license from IHS-,-,-KSC-STD-E-0002E March 12, 2009 This page intentionally left blank. iv Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-KSC-STD-E-0002E March 12, 2009 HAZARDPROOFING OF ELECTRICALLY ENERGIZED EQUIPMENT, STANDARD FOR 1.

10、PURPOSE AND SCOPE This standard sets forth requirements for hazardproofing electrical installations and equipment located in hazardous (classified) and other locations designated as hazardous by the authority having jurisdiction (AHJ) at Kennedy Space Center (KSC) to prevent ignition of flammable li

11、quids or hazardous fluids, gases, or vapors. This document defines the minimum requirement that KSC ground systems and equipment must meet. This document does not define how to design systems and equipment, or encompass hazardproofing requirements associated with lightning protection, grounding, ope

12、rational safety, toxicity, or chemical reactions. This standard does not apply to locations made hazardous because of the presence of high explosives (such as blasting agents or munitions) or pyrophoric materials (those that ignite spontaneously in air). 2. APPLICABLE DOCUMENTS The following documen

13、ts form a part of this document to the extent specified herein. When this document is used for procurement, including solicitations, or is added to an existing contract, the specific revision levels, amendments, and approval dates of said documents shall be specified in an attachment to the solicita

14、tion/statement of work/contract. Unless a specific edition is cited, the latest released edition applies. 2.1 Governmental 2.1.1 Specifications John F. Kennedy Space Center (KSC), NASA KSC-SPEC-E-0031 Cables, Electrical, Specification for 1 Provided by IHSNot for ResaleNo reproduction or networking

15、permitted without license from IHS-,-,-KSC-STD-E-0002E March 12, 2009 Military MIL-DTL-5015 Connectors, Electrical Circular Threaded, AN Type, General Specification for MIL-DTL-22992 Connectors, Plugs and Receptacles, Electrical, Waterproof, Quick Disconnect, Heavy Duty Type, General Specification f

16、or 2.1.2 Standards John F. Kennedy Space Center (KSC), NASA KSC-STD-132 Potting and Molding Electrical Cable Assembly Terminations, Standard for KSC-STD-E-0006 Instrumentation and Communications Cable Applications, Standard for KSC-STD-E-0011 Electrical Power Receptacles and Plugs, Standard for KSC-

17、STD-E-0014 Wire and Cable Applications, Standard for 2.1.3 Handbooks John F. Kennedy Space Center (KSC), NASA GP-864, Volume IIA Electrical Ground Support Equipment Cables Handbook 2.2 Nongovernmental National Fire Protection Association NFPA 70 National Electric Code NFPA 430 Code for the Storage o

18、f Liquid and Solid Oxidizers NFPA 496 Standard for Purged and Pressurized Enclosures for Electrical Equipment 2 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-KSC-STD-E-0002E March 12, 2009 NFPA 497 Recommended Practice for the Classification of Fla

19、mmable Liquids, Gases or Vapors and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas 2.3 Order of Precedence In the event of conflict between the documents cited herein and the contents of this document, the contents of this document shall supersede, except

20、where otherwise noted. The NASA contract, purchase order, or program-level documentation shall take precedence over the contents of this document in the event of conflicting requirements. Nothing in this document supersedes applicable laws and regulation unless a specific exemption has been obtained

21、. 3. DEFINITIONS For the purpose of this document, the following definitions shall apply. a. authority having jurisdiction (AHJ): Organization, office, or individual responsible for approving equipment, materials, an installation, or a procedure. At KSC, the NASA Fire and Rescue Office is the AHJ. b

22、. control drawing: Drawing or other document provided by the manufacturer of the intrinsically safe or associated apparatus (or of the nonincendive field wiring apparatus or associated nonincendive field wiring apparatus) that details the allowed interconnections between the intrinsically safe and a

23、ssociated apparatus or between the nonincendive field wiring apparatus or associated nonincendive field wiring apparatus. c. facility: Structure or building that serves a particular purpose. d. hazardous location: Location where fire or explosion hazards may exist because of the presence of flammabl

24、e gases, vapors, or liquids; combustible dust; or ignitable fibers or flyings. The area is classified in accordance with properties of the material responsible for the potential hazard and with the likelihood of the hazard actually being present. e. purged and pressurized: Condition achieved by (1)

25、purging, or supplying an enclosure with a protective gas at a sufficient flow and positive pressure to reduce the concentration of any flammable gas or vapor initially present to an acceptable level; and (2) pressurizing, or supplying an enclosure with a protective gas, with or without continuous fl

26、ow, at sufficient pressure to prevent the entrance of flammable gas or vapor, combustible dust, or ignitable fibers. (For further information, see NFPA 496.) 3 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-KSC-STD-E-0002E March 12, 2009 f. intrinsi

27、cally safe: “An assembly of interconnected intrinsically safe apparatus, associated apparatus, and interconnecting cables in that those parts of the system that may be used in hazardous (classified) locations are intrinsically safe circuits” (NFPA 70). 4. GENERAL REQUIREMENTS Design for all new elec

28、trical equipment to be used in hazardous (classified) locations shall comply with the intent of the applicable guidelines of NFPA 70 (latest released edition), NFPA 430 (latest released edition), NFPA 496 (latest released edition), and NFPA 497 (current version at start of project unless otherwise s

29、tated in project documentation). The lead design engineer shall coordinate the design and implementation of hazardproofing for electrically energized equipment with the NASA Fire and Rescue Office, the AHJ over such activities at KSC. 5. GUIDELINES Guidelines have been extracted from the NFPA 70A, A

30、rticle 500, and have been tailored to KSC-specific environment and requirements. 5.1 Hazardous Locations and Classifications All areas designated as hazardous (classified) locations shall be properly documented in KSC drawings (see Appendix A). This documentation shall be available to those authoriz

31、ed to design, install, inspect, maintain, or operate electrical equipment at the location. Hazardous locations are where fire or explosion hazards may exist because of the presence of flammable gases, vapors, or liquids; combustible dust; or ignitable fibers or flyings. Although combustible dust and

32、 flammable gases and vapors exist almost everywhere, they are usually present in only minute quantities, much less than necessary for a fire or explosion hazard to exist. Thus, the presence of flammable gases or vapors or combustible dust does not in itself define a hazardous location. These materia

33、ls must be present in sufficient quantities (concentrations) to present a potential explosion hazard. Hazardous locations at KSC involve the storage, handling and distribution of liquid oxygen, liquid hydrogen, nitrogen tetroxide, monomethylhydrazine, and open-grain solid propellants. NFPA 497 does

34、not assign the following items as hazardous substances nor does it assign an NEC group classification. The substances shall be treated as follows: nitrogen tetroxide Class I, Group C oxygen Class I, Group D methane Class I, Group D 4 Provided by IHSNot for ResaleNo reproduction or networking permitt

35、ed without license from IHS-,-,-KSC-STD-E-0002E March 12, 2009 In North America, hazardous (classified) locations are divided into three classes, based on the explosive characteristics of the material. The classes of material are further divided into divisions or zones, based on the risk of fire or

36、explosion that the material presents. Zones have three levels of hazard, whereas divisions have two levels. Table 1Table 1. Classes, Divisions, and Zones of Hazardous Materials illustrates the relationships among classes, divisions, and zones. Hazardous Material Class, Division Zone Gases or vapors

37、Class I, Division 1 Zone 0 and Zone 1 Gases or vapors Class I, Division 2 Zone 0 Locations shall be classified depending on the properties of the flammable vapors, liquids, or gases, or the combustible dust or fibers that may be present, and the likelihood that a flammable or combustible concentrati

38、on or quantity is present. Where pyrophoric materials are the only materials used or handled, these locations shall not be classified. Each room, section, or area shall be considered individually in determining its classification. 5.2 Purging and Pressurizing Purging is the process of supplying an e

39、nclosure with a protective gas at a sufficient flow and positive pressure to reduce the concentration of any flammable gas or vapor initially present to an acceptable level. This technique can be used to change a Class I or Class II, Division 1, location into a nonhazardous location or into a Divisi

40、on 2 location, or to change a Class I or II, Division 2, location into a nonhazardous location. It requires a noncombustible enclosure (which may be a control room or a machine room) that is first purged of any combustibles or flammables and then maintained at a positive pressure sufficient to preve

41、nt combustibles or flammables from entering the enclosure and being ignited by electrical equipment within the enclosure. The purging may be a continuous process or a single operation with a positive pressure maintained to make up for leaks. The pressurizing medium may be either air, commonly used i

42、n control rooms where people will be working, or a nonflammable gas. In instrument enclosures in locations with corrosive atmospheres, specially processed and dried air or gas is used to protect the enclosed equipment against corrosion, as well as to prevent ignition of exterior flammable gases and

43、vapors or combustible dust. (See NFPA 496.) Where possible, enclosures and distributors that are required by the system should be located outside a hazardous area and an intrinsically-safe design for energized electrical equipment is preferred. 5 Provided by IHSNot for ResaleNo reproduction or netwo

44、rking permitted without license from IHS-,-,-KSC-STD-E-0002E March 12, 2009 5.3 Equipment for Hazardous Areas 5.3.1 Class and Properties Equipment shall be identified for not only the class of location but also the explosive, combustible, or ignitable properties of the specific gas, vapor, dust, fib

45、er, or flyings that will be present. In addition, Class I equipment shall not have any exposed surface that operates at a temperature in excess of the ignition temperature of the specific gas or vapor. Class II equipment shall not have an external temperature higher than that specified. Class III eq

46、uipment shall not exceed the maximum surface temperatures specified in NFPA 70, Article 503.5. 5.3.2 Cable Wiring Methods Cable shall be protected from spillage of liquid oxygen, hydrogen, or other propellants and from mechanical damage. No electrical lines of any type shall be located in trenches c

47、ontaining propellant lines. Instrumentation, communication, control, and associated power equipment at KSC may be connected by hard-service cabling/cords as specified in GP-864, Volume IIA; KSC-SPEC-E-0031; KSCSTD-E-0006: or KSC-STD-E-0014. 5.3.2.1 Mineral-Insulated Cable Mineral-insulated cable is

48、suitable for Division 1 locations and for all Class I and Class II locations. (See GP-864, Volume IIA; KSC-STD-E-0014; KSC-SPEC-E-0031; and KSC-STD-E-0006.) 5.3.2.2 Metal-Clad Cable Metal-clad cable (Type MC) is permitted for application in Class I, Division 2, locations. Use of this type of cable is not limited to any voltage class. Under restrictions, metal-clad cable (Type MC-HL) and instrumentation tray cable (Type ITC-HL) are permitted in Class I, Division 1, locations. (See NFPA 70; GP-864,