MIL-STD-1542B MILITARY STANDARD ... - zandz.com · MIL-STD-285 MIL–STD-461 MIL–STD–462 MIL-STD-463 ... NACE 1430 Broadway, New York, N.Y. Association of Std. RP–01-69 10018

F==lMIL-STD-1542B (USAF)15NOV 91

SUPERSEDING

MIL-STD-1542A (USAF)Dated01 MAR 88

I MILITARY STANDARD

ELECTROMAGNETIC COMPATIBILITY

AND

GROUNDING REQUIREMENTS

FOR

SPACE SYSTEM FACILITIES -

AMSC NIA AREA EMCS

DISTRIBUTIONSTATEMENT A: Approvedforpublicrelease;distributionunlimited.

MIL-sTD-1542B (USAF)15 NOV 91

FOREWORD

1. This military standard is approved for use by the SpaceSystems Division, Department of the Air Force, and is availablefor use by all Departments and Agencies of the Department ofDefense.

! 2. Beneficial comments (recommendations, additions,deletions) and any pertinent data which may be of use inimproving this document should be addressed to:

USAF Space Systems Division, SSD/SDFCP. O. BOX 92960Worldway Postal CenterLos Angeles, CA 90009-2960

ii

by using the self–addressed Standardization Document ImprovementProposal (DD Form 1426) appearing at the end of this document orby letter.

MIL-sTD-1542B (U5AF)15 NOV 91

CONTENTS

I 1.

1.11.2

2.

2.12.22.3

3.

I

t

3.13.23.33.43.53.63.73.83.93.103.113.123.13

4.

4.14.24.34.44.54.6

5.

5.15.1.15.1.2

PAGE

SCOPE .................................................. 1

PURPOSE .............................................. 1APPLICATION .......................................... 1

REFERENCED DOCUMENTS.. ................................. 3

GOVERNMENT DOCUMENTS. ................................ 3NONGOVERNNENT DOCUMENTS. ............................. 4ORDER OF PRECEDENCE ................................... 5

DEFINITIONS ............................................ 7

FACILITY ............................................. 7SPACE SYSTEM FACILITY.. ...........................”... 7FACILITY GROUND NETWORK. ............................. 7LOW FREQUENCY CIRCUITS. .............................. 8HIGH FREQUENCY CIRCUITS. ............................. 8SINGLE POINT GROUNDING. .............................. 8MULTIPOINT GROUNDING. ................................ 9EQUIPOTENTIAL PLANE.... .......................:...... 9TECHNICAL POWER ...................................... 9FACILITY POWER ....................................... 9CATHODIC PROTECTION .................................. 9PRIMARY POWER ........................................ 1(ISECONDARY POWER ...................................... 10

GENERAL REQUIREMENTS ................................... 11

ELECTRICAL POWER CHAIUCTERISTICS ..................... 11ELECTROMAGNETIC COMPATIBILITY ........................ 11SHIELDING ............................................ 11FACILITY GROUND NETWORK. ............................. 11ELECTRICAL BONDING ................................... 12FILTERING ............................................ 12

DETAILED REQUIREMENTS. ................................. 13

ELECTRICAL POWER ..................................... 13Electrical Power Characteristics, .................. 13Electrical Power Distribution ...................... 13

5.1.2.1 Technical Power .................................. 135.1.2.2 Facility Power ................................... 145.1.3 Power Grounding .................................... 145.1.3.1 Primary Utility Power ............................ 14

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MIL-STD-1542B (USAF)15 NOV 91

CONTENTS

PAGE

I

5.1.3.25.1.3.35.1.3.45.1.3.55.1.3.65.1.3.75.1.3.85.1.3.9

5.25.2.15.2.2

Secondary Power .................................. 14Ground Fault Circuit Interrupters ................ 14Power Sources .................................... 14Thermostats and Heaters .......................... 14Small Power Tools.... ............................ 15Shop Equipment ................................... 15Voltage Regulators and Transformers .............. 15Power Control and Switching Equipment ............ 15

ELECTROMAGNETIC COMPATIBILITY .........................15Facility Interference Limits ....................... 15EMC Testing ........................................ 15

5.3 SHIELDING ............................................ 155.3.1 General ............................................ 155.3.1.1 Wire Shielding ................................... 165.3.1.1.1 General ........................................ 165.3.1.1.2 Grounding ...................................... 165.3.1.1.3 Isolation ...................................... 165.3.1.1.45.3.1.25.3.1.2.15.3.1.2.25.3.1.2.35.3.1.2.45.3.1.35.3.1.3.15.3.1.3.25.3.1.3.35.3.1.3.45.3.1.3.55.3.1.3.65.3.1.3.7

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Wire and Cable Routing ......................... 16 IShielded Equipment Enclosures ..................... 16Materials and Workmanship.Gaskets ...................Filters ...................Access or Ventilation Open:

Shielded Rooms ..............General ...................Doors .....................Grounding .................Transformers and Filters ....................... 18Penetrations ................................... 18Quality Assurance .............................. 18Testing ........................................ 18

. . . . . . . . . . . . . . . . . . . . 16

.................... 16

.................... 17rigs ................ 17 I.................... 17.................... 17.................... 17

..................... 17

5.4 FACILITY GROUND NETWORK. ............................. 18 I

5.4.15.4.1.15.4.1.25.4.1.35.4.1.45.4.1.55.4.1.65.4.1.7

Earth Electrode Subsystem. ......................... 18General .......................................... 18Earth Resistivity Survey. ........................ 18Resistance to Earth... ........................... 19Earth Electrode Subsystem Configuration .......... 19Ground Rods ...................................... 20Ground Feeders ................................... 20Power Transformer Grounding ...................... 20

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MIL-sTD-1542B (USAF)15 Nov 91

Commrrs

PAGE

I5.4.1.85.4.1.95.4.1.105.4.1.115.4.1.125.4.1.135.4.1.145.4.1.155.4.1.15.15.4.1.15.2

5.4.25.4.2.15.4.2.25.4.2.35.4.2.45.4.2.5.5.4.2.65.4.2.75.4.2.8

5.4.35.4.3.15.4.3.25.4.3.3

] 5.4.3.4

5.4.45.4 .4.15.4 .4.25.4.4.3

\5.4 .4.4

Ground Isolation ................................. 20Service Structures ............................... 20Service Structure Tracks ......................... 20Launchpad Structure. ............................ 20Passageways ...................................... 21Security and Perimeter Fences .................... 21Cathodic Protection.. ............................ 21Testing .......................................... 21

Resistance Measurements. ....................... 21Cathodic Protection. ........................... 21

Lightning Protection Subsystem .............:....... 21Buildings and Structures ......................... 21Air Terminals (Lightning Rods) ................... 21Roof and Down Conductors .......................... 22Structural Steel ................................. 22Waveguide Grounding.. ............................ 22Exterior Wires and Cables. ....................... 22Bonds ............................................ 23Lightning Transient Protection ................... 23

Equipment Fault Protection Subsystem ............... 23General .......................................... 23Conduit. Piues and Tubes ......................... 23Cable Trays-or Raceways ........Equipment Enclosures ...........

Signal Reference Subsystem (Techn:General ........................Low Frequency Circuits .........

. . . . . . . . . . . . . . . . . 23

................. 24

cal Ground) ...... 24................. 24................. 24

High Frequency Circuits .......................... 24Equipments Containing Both High and Low

Frequency Signal Circuits ...................... 25

5.5 FILTERS .............................................. 255.5.1 General ............................................ 255.5.2 Requirements ....................................... 255.5.2.1 Filters .......................................... 255.5.2.2 Design ........................................... 265.5.2.3 Fungus Resistance ................................ 265.5.2.4 Dissimilar Metals ................................ 265.5.3 Test Requirements .................................. 265.5.3.1 Qualification Testing.. .......................... 265.5.3.2 Insertion Loss ................................... 26

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CONTENTS

PAGE

5.65.6.15.6.25.6.35.6.45.6.55.6.65.6.7

BONDING .............................................. 26General ............................................ 26Corrosion Protection. .............................. 26Bond Straps ........................................ 27Bond Resistance .................................... 27Welding ............................................ 27Brazing and Silver Soldering ....................... 27Bonding of Copper to Steel. ........................ 28

5.6.8 Structural Steel ................................... 285.6.9 Metal Passageways. ..................................285.6.10 Facility Structural Steel .......................... 285.6.11 Movable Metallic Items ............................”.285.6.12 Bond Protection .................................... 285.6.13 Compression Bonds in Protected Areas ...........~~~~ 285.6.14 Bonding Tests ...................................... 29”5.6.14.1 Facility Bonding Test. ........................... 295.6.14.2 Bonding Joints ................................... 295.6.14.3 Test Equipment ................................... 295.6.14.4 Test Procedure ................................... 295.6.14.5 Success Criteria ................................. 295.6.14.6 Data Requirements ................................29

5.7 NATIONAL SECURITY INFORMATION (RED/BLACK EQUIPMENTS). 30

6.4 SUBJECT TERM6.5 SUPERSESSION

6. NOTES .................................................. 316.1 INTENDED USE ......................................... 316.2 TAILORED APPLICATION. ................................ 316.3 TOTAL QUALITY MANAGEMENT. ............................ 31

(KHWORD) LISTING ......................32DATA .................................... 33

FIGURES

Figure 1 -

Figure 2 –

Figure 3.

Figure 4 -

Low Frequency Technical Grounding .................. 34

Typical Equipotential Ground Plane Networkfor Multistory Buildings ........................ 35

High Frequency Equipment Grounding Network ......... 36

Shielded Room Grounding Network .................... 37

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I Figure 5 –.-

Figure 6 -

I

Figure 7 –

Figure 8 -

Figure 9 –


CONTENTS

PAGE

Details of Ground Rod or Earth ElectrodeSubsystem Installation. ............................ 38

Connections to Earth Electrode Subsystem ........... 39

Air Terminal Placement on Flat-roofed Structure .... 40

Equipment Fault Protective Subsystem Grounding ..... 41

Elements of the Signal Reference GroundSubsystem (with Equipotential Plane Ground) .,.......42

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Figure 10 - Detail of Typical Equipotential Ground PlaneI for New Construction - High Frequency

Facilities Installation. .....................’...43

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MIL-STD-1542B (u.5AF)15 NOV 91

THIS PAGE INTENTIONALLY LEFT BLANK

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‘IL-STD-1542B (u5AF)15 NOV 91

SECTION 1

SCOPE

1.1 PURPOSE

The purpose of this standard is to specify the design,performance, and verification requirements for electricalsubsystems for space system facilities, including electromagneticcompatibility (EMC), electrical power, grounding, bonding,shielding, lightning protection, and TEMPEST security. Theserequirements are interrelated and interdependent, and thereforerequire an integrated approach in the design.

1.2 APPLICATIOXl

This standard is intended primarily for use in design andconstruction contracts for space system facilities. Therequirements are applicable to all related facilities including,but not limited to, launch complexes, tracking stations, dataprocessing rooms, satellite control centers, checkout stations,spacecraft or booster assembly buildings, and any associatedstationary or mobile structures that house electrical andelectronic equipment. The requirements are not intended to beae!?licable to Lon9 Hall/Tactical Communication System Facilities(see MIL-STD-188-124A). The technical requirements for GroundSupport Equipment (AGE) used in direct support of space vehiclesare contained in MIL-STD-1541. The technical requirements forequipments installed in ground facilities (not a part of thefacility) are contained in MIL-STD-461.

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MIL–sTD-1542B (USAF)15 NOV 91


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SECTION 2

REFERENCED DOCUMENTS

2.1 GOVERNMENT DOCUMENTS

Unless otherwise specified, the following specifications,standards, and handbooks of the issue listed in that issue ofthe Department of Defense Index of Specifications and Standards(DoDISS) specified in the solicitation form a part of thisstandard to the extent specified herein:

MILITARY SPECIFICATIONS:

MIL-E-4158 Electronic Equipment Ground: GeneralSpecification For

MIL-F–15733 Filter, Radio Interference, GeneralSpecification for

MILITARY STANDARDS:

MIL–STD–188–124

MIL–STD–220

MIL-STD-285

MIL–STD-461

MIL–STD–462

MIL-STD-463

MIL-STD-889

MIL–STD–1541

Grounding, Bonding, and Shielding forCommon Long Haul/TacticalCommunications Systems

Method of Insertion-Loss Measurements

Attenuation Measurement for Enclosures,Electromagnetic Test Purposes, Method of

Electromagnetic Emission andSusceptibility Requirements for theControl of Electromagnetic Interference

Electromagnetic InterferenceCharacteristics, Measurement of

Definitions and Systems of Units,Electromagnetic Compatibility Technology

Dissimilar Metals

Electromagnetic CompatibilityRequirements for Space Systems

MILITARY HANDBOOKS:

MIL-HDBK–419 Grounding, Bonding and Shielding forElectronic Equipments and Facilities

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MIL–STD–1542B (USAF)15 NOV 91

OTHER GOVERNMENT DOCUMENTS :

AFM 88–4 Facility Design & Construction (AIRFORCE mu 88–4)

AFP 91-38 Maintenance of Electrical GroundingSystems (AIR FORCE PUBLICATION 91-38)

FIPS PUB 94 Guidelines on Electrical Power for ADPApplications (Federal InformationProcessing Standard Publication 94)

NACSIM 5203 (C) Guidelines for Facility Design andRed/Black Installation (U)

NACSEM 5204 (C) Shielded Enclosures (U)

(Copies of specifications, standards, handbooks, drawings, andpublications required by contractors in connection withspecified acquisition functions should be obtained from thecontracting activity or as directed by the contracting officer.)

2.2 NONGOVERNMENT DOCUMENTS

The following documents form a part of this standard to theextent specified herein. Unless otherwise indicated, the issuein effect on the date of invitation for bids or request forproposal shall apply.

American National Standards Institute:

ANSI C 84.1–1982 Power Systems - Voltage Ratings forElectric Power Systems and Equipment(60 Hz)

Application for copies should be addressed to:

American National Standards Institute.

National

NACE

1430 Broadway,New York, N.Y.

Association of

Std. RP–01-69

10018

Corrosion Engineers:

Recommended Practice - Control ofExternal Corrosion on Underground orSubmerged Metallic Piping Systems.

4



National Association of Corrosion Engineers,P.O. BOX 218340,Houston, TX 77218.

National Fire Protection Association:

NFPA No. 70 National Electrical Code

NFPA NO. 78 Lightning Protection Code


National Fire Protection Association,Batterymarch Park,Quincy, MA 02269

(Nongovernment standards and other publications are normallyavailable from the organizations which prepare or whichdistribute the documents. These documents also may beavailable in or through libraries or other informationalservices.)

2.3 ORDER OF PRECEDENCE

In the event of a conflict between the text of thisstandard and the references cited herein, the text of thisstandard shall take precedence. However, nothing in thisstandard shall supersede applicable laws and regulations unlessa specific exemption has been obtained.

MIL–STD-1542B (USAF)15 NOV 91


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SECTION 3

DEFINITIONS

Electromagnetic compatibility (EMC) terms are as defined inMIL-STD-463. Other terms are in accordance with the followingdefinitions:

3.1 FACI LI~.

A facility is a building or other structure, either fixedor transportable” in nature, with its utilities, groundnetworks, and electrical supporting structures. All wiring andcabling that is provided under terms of the facility contractare considered to be part of the facility. Any electrical andelectronic equipments required to be supplied and installed bythe facility contractor are also part of the facility.

3.2 SPACE SYSTEM FACILITY.

A space system facility is an earth–based facility thathouses technical equipment for the operational support of amilitary space system. The technical equipment may beelectrical, electronic, mechanical, optical, or any combination.

3.3 FACILITY GROUND NE~ORK .

The facility ground network is a network of conductors thatform direct low impedance paths between earth and variouspower, communications, and other equipments to effectivelyextend an approximation of ground reference throughout thefacility. The facility ground network is comprised of foursubsystems as follows:

a. Earth Elect rode Subsystem. The earth electrodesubsystem is a network of electricallyinterconnected rods, mats, or grids installed inthe earth for the purpose of establishing a lowimpedance contact with the earth.

b. Li.ahtnina Protec tion Subsystem. The lightningprotection subsystem is a low impedance path forlightning energy to the earth electrode subsystem.Air terminals must be provided to intentionallyattract the leader lightning strike. Roof anddown conductors carry the high currents away fromsusceptible elements in the facility and limitvoltage gradients developed by the high currentsto safe levels.

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MIL-STD–1542B (USAF)15 NOV 91

c. Equipment Fault Protection Subsystem. (FacilityGround). The equipment fault protection subsystemis a set of ground return conductors (green wires)that provide a current path to structure and theearth electrode subsystem of sufficient capacityso that protective devices (fuses and circuitbreakers) can operate properly to protectpersonnel from shock hazard and equipment fromdamage. It also encompasses all earth referencingof all noncurrent–carrying metallic objects suchas piping, ducts, conveyances, structural steel,air conditioning equipment, electric motorframes, electronic enclosures, etc.

d. Siqnal Refere ce Subsvstemn (Teehnical Groundl.The signal reference subsystem, or technicalground, is a network of conductors that providethe ground reference for all technical equipmentused for operational support. It provides theground reference for the signal circuits for thetechnical equipment that is related directly tothe military space system. It may consist of alow frequency grounding network (single pointgrounding), or hiqh frequency oroundina network~multipo~nt grounding) ;r a ~o~binatiofi thereof.The signal reference system shall not be used inlieu of safety ground conductors (green wires) asa path for fault currents.

3.4 LOW FREOUENCT CIRCUITS.

For the purposes of this standard, low frequency electricaland electronic circuits are those that operate in the frequencyrange from dc to 30 kilohertz.

3.5 HIGH FREOUE NCY CI RCUITS .

In this standard, high frequency electrical or electroniccircuits are those that operate above 30 kilohertz.

3.6 SINGLE POINT GROUNDING.

method of circuit and shieldof the system or subsystem hasa ground reference subsystem,given system or subsystem.

Single point grounding is agrounding in which each circuitonly one physical connection toideally at the same point for aSingle point grounding is effective only for low frequencycircuits where it is applied to prevent return currents fromflowing in structural elements resulting in ground loops andground reference potential differences. Power distributioncircuits utilize single point grounding. (See Figure 1)

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I 3.7 MULTIPOINT

MIL-sTD–1542t3 (uSAF)15 NOV 91

GROUND ING.

Multipoint grounding is a method of circuit and shieldgrounding which provides multiple low impedance paths for highfrequency signals to an equipotential plane constituting theground reference for high frequency signals and signaltransmission circuits. Multipoint grounding requires theexistence of an equipotential ground plane (See 3.8). Multipleconnections are made to the equipotential plane for highfrequency circuits by the shortest, lowest impedance method.

I High frequency circuits utilize multipoint grounding to theearth electrode subsystem.

3.8 EQUIPOTENTIAL PLANE .

An equipotential plane is a mass or surface of metal (solidor grid) that offers a negligible impedance to current flow sothat differences in electrical voltage are minimized across theplane (see Figures 2 and 3). An equipotential plane isconsidered an earth ground for a signal reference subsystem(technical ground) regardless of its elevation from physicalearth. The equipotential plane has multiple connections tostructural steel and to the earth electrode subsystem.

3.9 TECHNICAL POWER.

Technical power is the electrical power supplied to powercircuits of technical equipment used for the operationalsupport of a military space system, such as: checkoutequipment, test equipment, communications equipment, and dataprocessing equipment. Surge loads and electromagneticinterference are limited to prevent damage or malfunction of’electrical or electronic equipment. Large motors required to

I operate technical equipment are not connected to technicalpower circuits.

3.10 FACILITY POWER.

Facility power is the electrical power supplied to afacility for lighting, heating, air conditioning, large surgeloads, large electric motors, and other station-keepingfunctions.

3.11 CATHODIC PROTECTION ,

A technique to prevent corrosion of a metal surface bymaking that surface the cathode of an electrochemical cell.


3.12 PRIMARY POWRR.

Primary power is the electrical power supplied to afacility from a utility or generation source.

3.13 SECONDARY POWRR.

Secondary power is electrical power that has passed througha conditioning device such as a transformer or converter.

An uninterruptible power system is a back-up electricalpower system to provide continuous electrical power for aperiod of time in the event of the failure the main powersource.

3.15 LOW LEVRL SIGNAL LINRS

I LOWof less

level signal lines are those that have maximum voltagesthan one volt.

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SECTION 4

GENEIWL REQUIREMENTS

4.1 ELECTRICAL PoWER CHARACTE RISTICS.

When commercial electrical power quality or reliability isnot sufficient to meet the program requirements, alternatemethods such as dedicated power generation, power conditioning,motor generators, or uninterruptible power systems (UPS) shallbe evaluated and utilized as required to meet the program needs.

4.2 ELECTROMAGNET IC COMPATIBILITY.

Facility electrical and electronic subsystems and equipmentshall be compatible with each other as well as with thetechnical equipment installed in the facility for support ofspace system operations. To achieve this goal with a highprobability of success the imposition of conducted and radiatedEMI limits on the facility equipment is required.

4.3 SHIELDING.

Shielding shall be provided for the protection of circuits,equipment, and groups of equipment; for electromagneticcompatibility within the system; and to comply with security(TEMPEST) requirements.

4.4 FACILITY GROUND NE3WORK .

All space system facilities containing electrical orelectronic technical equipment shall have an earth-referencedfacility ground network. The facility ground network shallconsist of the following electrically interconnected subsystems:

a. The earth electrode subsystem.

b. The lightning protection subsystem.

c. The equipment fault protection subsystem.

d. The signal reference (technical ground) subsystem.

These items together constitute the total grounding network forthe facility. The grounding of either fixed or mobilefacilities shall comply with the criteria of MIL-HDBK-419.

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MxL-STD-1542B (USAF)15 NOV 91

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4.5 ~ BONDING.

Electrical bonding is the procedure by which the conductivesurface of a component or subassembly is electrically connectedto another in a manner which provides a low impedanc~ pathbetween them. This reduces the development of electricalpotentials between the interfacing surfaces for frequenciescapable of causing interference. Low impedance bonding shallbe provided as required for safety, for electromagneticcompatibility within the system, and to comply with security(T~E5T) requirements.

4.6 FILTERING .

Filtering shall be provided for the purpose of establishingelectromagnetic compatibility, TEMPEST, or shielded enclosureintegrity. The design, performance, and testing of EMI filtersshall be in accordance with the requirements specified herein.

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SECTION 5

DETAILED REQUIREMENTS

5.1 ELECTRICAL POWRR.

5.1.1 Electrical Power Characteristics. Power qualityrequirements cannot be imuosed on commercial power sources whenth;se are utilized for space system facilities;. If commercialpower quality is not sufficient to meet program requirements,power conditioning equipment shall be provided. Unlessotherwise specified, power conditioning equipment includingmotor generators, uninterruptible power subsystems (UPS), anddc power supplies shall comply with Part 9 of MIL-STD-461 andoperate successfully to provide the following power sourceenvironment:

a.

b.

c.

d.

e.

f.

Voltage Regulation

Frequency Regulation

Harmonic Distortion

Transients

Distribution Voltage

Transformer

L5 percent no-load tofull-load with power factorranging from 1.0 to 0.8lagging

11 Hertz for 60 to 400 Hz

5 percent total

MIL–STD-461 Part 3, Paragraph5.2

Standard commercial voltagesin accordance with ANSI C84.1 shall be utilized, butnot less than 480 volts.

Unless otherwise specified,the electrical powertransformer shall be aDELTA-WYE configuration.

5.1.2 Electrical Power Distribution

5.1.2.1 Technical PoweE The technical power feedersfrom the main power distribu~ion panel shall be isolated byseparate transformers from facility power feeders. Multipletechnical power transformers shall be used to isolate power,circuits between users and subsystems to provide electromagneticcompatibility. User transformers shall be the isolation type.Technical power characteristics shall comply with MIL-E-4158.

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r41L-sm-1542fI (uSAF)15 NOV 91

Guidelines for technical power for computercontained in AFM 88–4 and FIPS PUB 94.

facilities are

5.1.2.2 Fac”litv Powe~. Facility power feeders from thefacility main po~er distribution panel shall be in separate

I conduits from technical power feeders and serve separatedistribution buses.

5.1.3 Power Groundinq.

5.1.3.1 Primarv Utilitv Power. Primary power neutralsshall be grounded to the equipment fault protection subsystemonly at the service disconnect means, as shown in Figure 1 andFigure 8. Transformers supplying technical equipment shall beof the isolation type (i.e., primary windings mechanically andelectrically isolated from the secondary winding), withelectrostatic shielding incorporated. Transformers shall beDELTA-WYE. Neutral/return side power switching shall not beused. Further guidance for power grounding is provided in AFP91–38.

5.1.3.2 Secondarv Power. Secondary power that isconverted from primary utility power shall have dc resistanceisolation of 1 megohm or greater between the secondary andprimary power measured at the transformer terminals. Thevarious secondary power subsystems shall have dc resistanceisolation of 1 megohm or greater between each other. Secondarypower neutrals shall be single-point grounded to the equipmentfault protection subsystem at the transformer or at the load assystem requirements dictate. Sensitive electronic equipmentshall be powered through a shielded isolation transformer to atechnical equipment bus.

5.I..3.3 Grou d Fault Clrcuxt. .

I ter Dtew Receptacleoutlets for 120-v~lt single phase (?5- ~~d 20–~mpere) shallhave ground fault circuit interrupters (GFCIS) where requiredfor personnel protection by the National Electrical Code,Articles 210 and 215, (NFPA No. 70).

5.1.3.4 Power Sources. Rotary or other power sourcesshall have their frames and cases bonded to the equipment faultprotection subsystem. Load current and voltage unbalance amongphases shall be limited as indicated in FIPS PUB 94.

I 5.1.3.5 Thermostats and Heate~. The control of primarypower by a thermostat is permitted only through a relay; the-relay shall be EMI suppressed and shielded. The relay andthermostat case shaII be referenced to the equipment faultprotection subsystem. The metal case of the associatedstep-down transformers shall also be referenced to theequipment fault protection subsystem. Connections between

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thermostat and the control relay shall utilize a shieldedtwisted pair of wires, with the shield grounded at both ends.The shield shall not be used to carry current intentionally.

5.1.3.6 small Power Tools. Small power tools shall havea case ground connection provided from the tool chassis to thewall receptacle or shall be double insulated.

5.1.3.7 Shov EUUiDMf3nt. All items such as motor caseequipment frames shall be bonded to the equipment faultprotection subsystem in accordance with requirements stipulatedin MIL-HDBK-419.

5.1.3.8 ~ae Regulators and Transfer e.z%i Voltageregulators and transformers used for voltagemreg~lating shallhave their frames and cases bonded to the equipment faultprotection subsystem.

5.1.3.9 Power contro 1 and Switchina Ecfuipmen~. Allpower circuits, switch gear, motor control, and control centerdistribution panels shall be bonded, shielded, and grounded toprovide for the attenuation of radiated interference. Allmetal parts shall be bonded to the equipment fault protectionsubsystem.

5.2 ELECTROMAGNETIC co MPATIBILITY .

5.2.1 Facilitv Interference Limi~, Unless otherwisespecified, the conducted and radiated requirements ofMIL-STD-461 shall apply as follows to facilities electricalequipment:

Parts 1 and 3 for Fixed and Mobile Ground

I a“Facilities Equipment (Class A3). See Table 4-1of MIL-STD-1541 for Types of Equipment.

b. Parts 1 and 7 for Noncritical Ground Areas (ClassB - Shop Equipment)

Ic. Parts 1, 9, and 10 for Electrical Power Equipment

(Such as generators and UPS)

ICommercial off-the-shelf (COTS) equipment that is installed

as a part of a facility shall meet the requirements specifiedin Part I of MIL-STD-461.

5.2.2 EMC Testing. Compliance with Paragraph 5.2.1requirements shall be determine& by tests performed inaccordance with MIL-STD-462 or contracting officer approvedtest plans.

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MIL-5TD-1542B (U5AF)15 NOV 91

5.3 ~HIELDING.

5.3.1 General. Shielding shall be utilized along withother basic interference control measures such as filtering,wire separation, wire twisting, circuit layout, spectrumcontrol, and frequency assignment to achieve electromagneticcompatibility within and between systems. The degree ofshielding shall be determined by the systems engineeringanalysis process to meet the requirements of this standard andof the system.

5.3.1.1 ~q.

5.3.1.1.1 General. A double, triple, or solid conduitshield shall be used where a single overall shield is not Iadequate. Shields shall not be used aa intentional current-carrying conductors, except for high frequency transmissionlines.

5.3.1.1.2 Groundinq. High frequency shields (coax,twinax, shielded twisted pairs, and multiconductor cableshields) shall be grounded at both ends and at every pointwhere a discontinuity exists at metal enclosures. Lowfrequency circuit shields shall be grounded at one end only; atthe source end for interference-generating circuits and at theload end for interference–sensitive circuits. The shield shallmaintain continuity through metallic enclosures and panels.High frequency shields shall be grounded circumferentially toor inside connectors or equipment enclosures with nodiscontinuities in the external shield.

5.3.1.1.3 Isolation. Except for solid conduit shields,shields shall be isolated from each other and from any metalliccomponent by at least 1 megohm (de) when shield grounds arelifted. Except as may be specified in the contract, solidconduit shields shall not be isolated from each other or fromstructure.

5.3.1.1.4 w~ ing. The routing andlayout of wires and cables shall be performed in a manner thatdoes not jeopardize the integrity of the equipment shield.Cables or wirea carrying high level signals shall be routed aminimum of 0.1 meters (4 inches) from level power signallines. Power lines shall be separated from sensitive digital Ior other susceptible circuits. Power distribution wiring shallbe in steel conduit, cable trays, or raceways.

5.3.1.2 ~ res.

16

MIL-STD-l542B (USAF)15 NOV 91

5.3.1.2.1 Materials and Workmanship. Equipment shieldsshall be constructed of materials that provide the requiredattenuation of electromagnetic interference. Materials shallbe corrosion resistant and compatible as defined byMIL–STD-889 . Materials and workmanship shall be in accordancewith MIL-HDBK-419.

5.3.1.2.2 Gaskets. Conductive gaskets, finger stock, orother sealing devices shall be installed on all doors, covers,joints, seams, or other closures that require frequent openingto the extent necessary to provide electromagneticcompatibility in their intended environment. Door sealingdevices shall withstand 10,000 open–close cycles withoutmaintenance and retain the required attenuation. Beyond 10,000cycles, maintenance procedures and periodic testing to retainthe required attenuation shall be developed and documented.

5.3.1.2.3 Filters. Filters shall be installed whererequired for interference control on power, control, and signallines in a manner that maintains the integrity of the shield.Filters shall comply with the requirements of MIL-F-15733 andParagraph 5.5 of this Standard.

5.3.1.2.4 Access or Ventilation Openin~. All access 01ventilation openings shall be covered in accordance with thecriteria of MIL–HDBK-419.

5.3.1.3 Shielded Rooms.

5.3.1.3.1 General. Shielded rooms shall be providedwhen required for the control of National Security Information(Red/Black Criteria) signals or to provide a quietelectromagnetic environment for operation or testing ofelectrical and electronic devices. Shielded rooms shall meetthe requirements of this standard as well as the requirementsof Appendix B of NACSSM 5204 and Appendix O of NACSIM 5203.The attenuation requirements of the shield room walls, doors,and penetrations shall be as specified in the above referenceddocuments or as specified in the contract. Welded rooms shallbe welded by means of the Metal Inert Gas (MIG) arc weldingprocess. Welders shall be certified for the MIG weldingprocess.

5.3.1.3.2 Doors. Doors that utilize finger stock shallbe of the recessed contact design. The recessed contact shallprovide protection and wiping action shall be provided tomaintain a low impedance contact. The cycling and maintenancerequirements of Paragraph 5.3.1.2.2 shall apply.

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5.3.1.3.3 Groundinq. Internal and external grounding ofthe circuits and the shielded room shall be in accordance withFigure 4 and MIL-HDBK-419. High frequency grounding inside theshielded room shall be by welding to the inside of the shieldedroom wall. If low frequency (single point) grounding isrequired inside shielded areas, it shall be provided by theuser, and the ground shall be at a single point as shown inFigure 4. The exterior of the room shall be grounded to theearth electrode subsystem and structure at multiple points. ICable size shall be in accordance with Paragraph 5.4.1.6.

5.3.1.3.4 Transform s d F.lte s Transformers andfilters may be located o~rei%er ~he ;u~side or inside wall ofthe shielded room. The external enclosures of these unitsshall be bonded to the shield wall in either case.

5,3.1.3.5 penetrations. Penetrations shall be made in amanner which meets the operational function while maintainingthe integrity of the RF shield. All shielded room penetrationsshall meet the requirements of Appendix B of NACSEM-5204 andAppendix O of NACSIM 5203. Warranty requirements of thesedocuments shall apply.

5.3.1.3.6 Quality Assurance. All seams and penetrationsshall be tested during construction to validate seam weldingquality by means of “sniffer” type EMI test equipment that hasbeen approved by the contracting officer. \

5,3.1.3.7 Test inq. The shield attenuation testing shallbe performed in accordance with MIL-STD–285, MIL–STD-220 and IAppendix B of NACSSM 5204. Test frequencies and test pointlocations shall be as specified in the contract, or in a testplan approved by the contracting officer. The receivingantennas shall be positioned and oriented for maximum signalpickup.

5.4 FACILITY GROUWD WETWORK.

5.4.1 Earth Electr ode Subsystem.

5.4.1.1 General. An earth electrode subsystem shall beinstalled at each space system facility to provide a lowimpedance path to earth for lightning and power fault currents,and to ensure that hazardous voltages do not occur within thefacility. This subsystem shall be capable of dissipating toearth the energy of direct lightning strikes with no ensuingdamage to itself. This subsystem shall also interconnect alldriven electrodes and underground metal objects of thefacility. The earth electrode subsystem for either fixed ormobile facilities shall be designed in accordance with

IMIL–HDBK-419 .

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5.4.1.2 Earth Resistivity Survey. The design of theearth electrode subsystem shall be based on an earthresistivity survey conducted at the site prior to the detaileddesign. The magnitude of earth resistivities shall be measuredand recorded. Natural features such as rock formations andunderground streams, as well as man-made features that have aneffect on earth resistivity, shall be recorded. This datashall be documented as a part of the facility design data.

I 5.4.1.3 Resistance to Earth. The dc resistance to earthof the earth electrode subsystem shall be 10 ohms or less.Lower earth electrode subsystem resistance shall be consideredfor areas that have high lightning incidence to lower the

1 probability of equipment damage. Where 10 ohms or less cannotbe obtained with the basic electrode configuration due to highsoil resistivity, rock formations, or other terrain features,alternate methods for reducing the resistance to earth shall beconsidered. These considerations include, but are not limitedto, the following:

a. Increasing the number of ground rods.

b. Use of longer rods.

c. Use of horizontal wires or grids instead ofvertical rods.

d. Lowering of the soil resistivity through chemicalenhancement. (See AFP 91-38)

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This Standard, MIL-HDBK-419, and MIL-STD-188-124 do notrecommend the use of deep wells for the achievement of lowerimpedance to earth. Deep wells do achieve low dc resistance,but have very small benefit in reducing ac impedance. Theobjective of the earth electrode subsystem is to reduce ac anddc potentials between and within equipments. If deep wells areutilized as a part of the earth electrode subsystem groundingnet, the other portions of the facility ground network shall beconnected to them.

If a separate power source (substation) earth electrodesubsystem is utilized, the resistance to earth shall not exceed

MIL-HDBK-419 provides further information on earth] ~~e%%esubsyatems design andthe reasons therefore.

5.4.1.4 Earth Electrode SubsYstem Confiaur ation. Thebasic earth electrode subsystem shall consist of driven groundrods uniformly spaced around the facility and placed 0.6 to 1.8meters (2 to 6 feet) outside the drip line of structures. Therods shall be interconnected with number 4/0 AWG (American WireGage) bare copper cable buried at least 0.6 meters (2 feet)

19

MIL–STD-1542B (USAF)15 NOV 91”

below qrade (see Fi.sure 5 and 6). The interconnecting cableshall ~e welded to =ach ground rod and close on itsel~ to forma complete loop. MIL–HDBK–419 provides additional guidance forthe design of earth electrode subsystems. All structural steelcolumns shall be connected to the earth electrode subsystem bynumber 4/0 AWG bare copper cable and all connections shall bewelded.

5.4.1.5 moud Rork.n Ground rods shall be copper cladsteel, a minimum of 3 meters (10 feet) in length, spaced apartnot more than twice the rod length, and shall not be less than19.0 millimeters (0.75 inches) in diameter. Difficultinstallation conditions may require shorter rod lengths. Thethickness of the copper jacket shall not be less than 0.3millimeters (0.012 inches). If deeper rods are required tomeet the earth resistivity requirements of Paragraph 5.4.1.3,threaded rod extensions of the same specifications may beused. Extension joints shall be welded.

5.4.1.6 Ground conductors . The lightning downconductors, the signal reference conductor, and the equipmentfault protection conductors shall be welded to the earthelectrode subsystem. The cross sectional area of the groundconductors shall be 2,000 circular roilsper running foot (3.32square millimeters per meter) and shall not be smaller thannumber 4/0 AWG.

5.4.1.7 ?~ Tra G inq. Utility powershall be ground~d to the ea~h elec?rode subsystem only at theneutral of the secondary of the subsystem transformer orservice disconnect as required by NFPA 70.

5.4.1.8 Ground Isolation. Low frequency signalreference subsystems (technical ground) shall be isolated fromother ground subsystems except at connection to the earthelectrode subsystem.

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5.4.1.9 Service Structurejs. Metallic structures, suchas service towers, umbilical towers, and cherry pickers, shallbe connected to the nearest earth electrode subsystem groundplate by number 4/0 AWG bare copper cable or tubing. Thegrounding cable shall be as short as possible and not exceed 30 Imeters (ioo feet). I

5.4.1.10 Service Structure Tracks. The roll-back tracksshall be grounded by connecting a number 4/0 AWG bare coppercable or equivalent tubing to the nearest earth electrodesubsystem ground rod, cable, or plate. The groundingconductors shall be as short as possible and not exceed 30meters (100 feet), and must meet the criteria of paragraph5.4.1.6.

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5.4.1.11 Launch Pad StUctur~. The launch pad structureshall be electrically bonde~ in accordance with Paragraph 5.6and shall be grounded to the earth electrode ground subsystemby number 4/0 AWG (minimum) bare copper cables. The groundingcables shall be as short as possible and shall must meet 30meters (100 feet).

5.4.1.12 Passaaewavs. The homogeneous bonding of themetal network of the interconnecting passageways shall begrounded by connecting the network of passageways to thebuilding structure by number 4/0 AWG bare copper cable. Thegrounding cable shall be as short as possible and shall meetthe criteria of paragraph 5.4.1.6.

5.4.1.13 Fecuritv a dn Perimeter Ferices. All securityand perimeter fences shall be grounded according to proceduresoutlined in MIL-HDBX-419.

5.4.1.14 Cathodic Protec~. Cathodic protection ofunderground pipes or structures shall be designed and installedin accor~ance with the guidance provided in MIL-HDBK-419 andNACE Standard RP-01-69. Cathodic protection subsystems shallbe isolated from the earth electrode subsystem.

5.4.1.15 Test inq.

5.4.1.15.1 Resistance Measurement. The resistance toearth of the earth electrode subsystem shall be measured by thefall of potential method (see MIL-HDBK-419) during dry surfacesoil conditions prior to completion of construction ofstructures, in order to comply with the requirements ofParagraph 5.4.1.3. Dry surface soil is defined as no rainfallduring the previous three-day period. Under dry surface soilconditions, it is recommended that resistance to earthmeasurements be made at least at three month intervals for thefirst year and at 21 month intervals thereafter. Foradditional test information, see MIL-HDBK-419.

5.4.1.15.2 Cathodic ProtecO. Cathodic protectionsubsystems shall be tested for compliance, and maintained, usingthe criteria and methods established by NACE S“tandard RP-01-69.

5.4.2 Liuhtnina Protec tion Subsvstem.

5.4.2.1 Buildinas and Structures. Lightning protectionshall be provided for all space system facilities andstructures including, but not limited to, substations,technical equipment buildings, towers, antennas, and masts.

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5.4.2.2 ~ rminal Liqhtnina Rodsl. Air terminalsshall be designed and installed in accordance with NFPA No. 78,MIL–HDBK–419 , and Figure 7 of this Standard. Refer toMIL–HDBK–419 and NFPA No. 78 for air terminal placement onnonflat–roof configurations and to Figure 7 for air terminalplacement on flat-roofed structures.

5.4.2.3 Roof and Down Conductors. The roof and downconductors shall be number 4/0 AWG minimum bare copper cablesand shall comply with requirements of paragraph 5.4.1.6 andshall be spaced not more than 15 meters (50 feet) apart (seeFigure 7). Roof and down conductor spacings of Figure 7 alsoapply to nonflat-roof configurations. Down conductor bendsshall have a radius greater than 200 millimeters (8.0 inches).Down conductors shall be located external to structures. Eachdown conductor shall be connected only to the structural steelonly at the base of the building by welding, that conductor inturn is connected to the earth electrode subsystem by welding.A minimum of two conductive paths shall exist between airterminals and the earth electrode subsystem. All downconductors shall have a ground rod at the base of each downconductor (Fig. 6). All buried cables shall be connected toground rods at 15 meter (50 foot) intervals.

5.4.2.4 ~. Substantial metal structuralelements of buildings and towers shall be acceptablesubstitutes for lightning down conductors provided they arebonded in accordance with Paragraph 5.6.5 and the buildings donot contain sensitive electronic equipment. The air terminalcables shall be welded or brazed to the peripheral steelcolumns of the building. The bases of the steel columns shall

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be connected to the earth electrode subsystem by number 4/0 AWGbare copper cables. Multiple structure lightninq groundsystems shall be connected together by a minimum of twoconductors conforming to paragraph 5.4.1.6. I

5.4.2.5 Wavequide Groundinq. As a minimum, allwaveguides located external to buildings shall be grounded asfollows:

a. Waveguide to antennas shall be grounded as ahinimum to the earth electrode subsystem at threepoints: at the antenna, at the base of thetower, and at the waveguide entry port usingnumber 6 AWG bare copper wire (as a minimum).

b. Metallic supporting structures for waveguideshall be electrically continuous and arounded tothe earth electrode ~ubsystemcolumns using number 6 AWG as

at all ;upportinga minimum.

22

MIL–STD-1542B (uSAF)15 NOV 91

5.4.2.6 Exterior Wires and Cables. Corrosion-protectedsteel conduit shall be used to enclose all external power or

I signal lines above or below ground to shield against lightningor lightning-induced currents and voltages. Junction boxesshall be electrically bonded to the conduit. The conduit shallbe connected to the earth electrode subsystem at each end, and

I h~veground rods at15meter (5~foot)intervalS. Theuseoffiber optic cables to guard against lightning induced voltageis recommended for external signal circuits. If fiber opticcables are not used, the circuit protective devices ofParagraph 5.4.2.8 are required.

5.4.2.7 Bonds. All bonds between elements of thelightning protection subsystem shall be welded or brazed. Allstructural steel members shall be bonded to each other bywelding.

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5.4.2.8 Liahtnina Transient Protect ion. All power andsignal circuits that may be damaged or malfunction as a resultof lightning-conducted or induced transients shall be protectedagainst pulses that have the characteristics as specified inMIL–E-4158. Information on voltage limitations and surgeprotecting devices is contained in MIL-HDBK-419. Power andsignal lightning arrestors shall be installed in accordancewith the National Electrical Code and MIL-HDBK–419.

5.4.3 EauiDment Fault Protection Subsvstem.

5.4.3.1 General. The equipment fault protectionsubsystem grounding conductor (green wire) protects personnelfrom hazardous voltages, prevents static charge buildup, andprovides a return conductive path for fault currents back to”the power source so that the protective circuit breaker or fusecan clear faulted current. To protect personnel and equipmentfrom hazardous voltages, all exposed metallic elements andenclosures of electrical or electronic equipment shall beconnected to the earth electrode subsystem by means of thegreen wire. A ground bus shall be provided in all electricalequipment cabinets, power panels, and switch gear cabinets, anda separate connecting grounding conductor (green wire) shall becarried within the same conduit or raceway as the ac powerconductors. The installation shall comply with therequirements of Article 250 of the NFPA No. 70. Usefulguidance information is provided in MIL-HDBK-419. A typicalequipment fault protection subsystem conductor arrangement isshown in Figure 8.

5.4.3.2 Conduit. Pipes and Tubes. Metallic conduit,pipes, and tubes shall be electrically continuous and shall begrounded to the equipment fault protection subsystem grounding

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network as shown in Figure 8. All conduit, whether used forpower, signal, or control wires, shall use lock nuts along withconductive lubricants to provide continuous conductivity.Conduit brackets and hangers shall be electrically continuousto the conduit and to the metal structures to which they areattached.

5.4.3.3 ~ and Racew~. The individualsections of cable tray assemblies and raceways shall beelectrically bonded to each other and to the structures thatsupport them. All cable tray assemblies and raceways shall beconnected to the equipment fault protection subsystem within0.6 meters (2 feet) of each end of the run and at intervals notexceeding 15 meters (50 feet) along each run.

5.4.3.4 ~auiument Enclosures . All electrical andelectronic wiring, distribution equipment enclosures, and theframes of electrical equipment, such as motors, generators, andfilters shall be connected to the equipment fault protection Isubsystem ground network as shown in Figures 8 anti9.

5.4.4 Siqnal Refere nce Subsvst~ nd .

5.4.4.1 ~ee al A signal reference subsystem(technical grou~d~ s~all be provided at each facility in whichelectronic equipment is installed to provide the groundreference connection from the earth electrode subsystem to allsignal circuits in the technical equipment used for operationalsupport. Signal circuits are grounded to control staticcharges, control electromagnetic interference, and establish acommon reference for signals between sources and loads.Additional information on the design of signal referencesubsystems is contained in MIL–HDBK-419 and Appendix B ofMIL–STD-188-124 . Communication and data cables betweensensitive electronic equipments shall be referenced to signal

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ground via surge arrestors where indicated as determined bydesign analysis. i

5.4.4.2 W~ itis. The signal referencesubsystem (technical ground) for low frequency signal circuits(from dc to 30 kilohertz) shall be connected to the earthelectrode subsystem at one point only (single point) and shallbe configured to minimize conductor path length. Low frequencygrounding pIates shall be isolated from structure by at leastone megohm by test when measured with the ground cabledisconnected. This grounding technique reduces stray currents(primarily 60 Hertz) which minimizes voltage potentials betweenpoints on the facility, thus minimizing common modeinterference between power and signal circuits. For additionalguidance, consult MIL–HDBK-419. Power distribution boxes may

24

MIL–sTD-1542B (U.5AF)15 NOV 91

Ibe grounded to structural elements. Power and low frequencysignal circuits utilize separate paths to this earth electrodesubsystem.

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5.4.4.3 Hiqh Frequency Circuits. The signal referencesubsystem, or technical ground, for higher frequency signalcircuits (above 30 kilohertz) requires an equipotential groundplane. Digital circuits are considered higher frequencycircuits. Figures 2, 3, 9, and 10 provide information ontypical equipotential ground planes and how equipment is to beconnected to it. If the equipotential plane is imbedded inconcrete, stub-ups as shown in Figure 10 or equivalent shall beavailable at five foot intervals in both directions. Theequipotential ground plane shall be connected to the facilitystructure at multiple points. Various configurations can beused based on the frequencies involved, such as copper grids,structural steel elements, the reinforcing rods (Rebar), orflat copper sheets that can be installed under or overequipment. Equipment cabinets shall be connected to theeguipotential plane and become a part of the equipotentialplane. Chassis shall be connected to the equipment cabinetsand all components, signal return leads, etc., shall beconnected to the chassis. Connections from technical equipmentto the equipotential ground plane shall be as direct aspossible and shall utilize low impedance ground straps. Highfrequency equipotential ground planes shall be designed andinstalled in accordance with MIL-HDBK-419. Technical groundplates for multipoint grounding shall be welded directly to theequipotential plane where ever possible or to substantialmetallic structure in the local area, or connected to a localcommon ground point which includes a low resistance conductor,to the equipotential plane. The equipotential plane shall beterminated to the earth electrode subsystem to assure personnelsafety and a low impedance path for low and high frequencysignals.

5.4.4.4 Ea iuments containina Both Hiah and Low FreuuencySirmal Circuits. Equipments that have both high and lowfrequency circuits and must share a common ground because ofdesign or construction requirements, shall be grounded asindicated for high frequency equipments as outlined inMIL-HDBK-419.

5.5 FILTERS.

5.5.1 General. This section of the.standard establishesthe requirements for EMI filters utilized for electromagneticcompatibility (EMC), National Security Requirements, or

Ishielded enclosure integrity and encompasses the design,performance, and testing of EMI filters. Optical isolators


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meeting the performance requirements of this standard areacceptable for providing isolation of control andcommunications circuits in shielded enclosure penetrations.

5.5.2 Reouirementi,

5,5.2.1 ~S. Filters shall be installed whereindicated by analysis at distribution panels that provide powerto SMI-sensitive equipment, or into rooms where such equipment

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is installed. The filters shall be part of the distributionpanel and shall provide a minimum attenuation of 100 decibels(dB) (unless otherwise specified) between 100 kilohertz and 400megahertz. Adequate filtering shall be provided on circuits I

from any source “that generates interference that may beconducted into EMI-sensitive equipment areas. Filters used inthis application shall conform to MIL-F-15733.

5.5.2.2 Desiqn Filters shall be designed in accordancewith the requiremen~s of MIL-F-15733. The design shall includeprevention of underdamped resonant conditions between thesource and load which would cause excessive voltages that candegrade the filter elements. Additional performancerequirements may be specified in the contract.

5.5.2.3 Funqus Resistance. Materials used in the filtershall be fungus resistant or shall be treated to resist fungus.

5.5.2.4 Dis similar Metals. Dissimilar metals, asdefined by MIL-STD-889, shall not be used in contact with eachother unless protected against galvanic corrosion. When it isnecessary that dissimilar metals be assembled together, amaterial compatible with each shall be interposed between them.

5.5.3 Test Reauir ements.

5.5.3.1 ~ification Testinq. Filters shall be testedin accordance with the requirements and test methods ofMIL-F-15733. Except for the insertion loss test, it isacceptable for the contractor to submit certified copies oftest reports of units of the same design.

5.5.3.2 Insertion Loss, The full load insertion lossshall be measured utilizing the approach outlined inMIL-STD-220, except that the insertion loss shall be measuredfor the full frequency range of the filter. The minimum numberof measurements shall consist of three measurements per decade(factor of ten in frequency). Simulated load impedances shallbe used during the test. If load impedances are not known, theload impedances to be used shall be as estimated and approvedby the contracting officer.

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5.6 BONDING

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5.6.1 General. Bonding is the process by which a lowimpedance path for the flow of electric current is establishedbetween two metallic objects. Facilities containing electricalor electronic equipment shall be constructed so thatinterconnections between metallic objects prevent electricshock hazards, provide lightning protection, establishreferences for electronic signals, and reduce EMI. The jointsshall be protected against corrosion or other means ofdegradation.

5.6.2 Corrosion Protect ion. Bonds shall be galvanicallycompatible as defined by MIL-STD-889. Bonds shall be protectedagainst weather, corrosive atmospheres, vibrations, andmechanical damage if the possibility of exposure to theseenvironments exist where they are located at the facility.

5.6.3 Bond Straps. Bonding straps installed acrossshock mounts or other suspension or support devices shall notimpede the performance of the mounting device and not suffermetal fatigue or other means of failure. High frequency bondstraps shall have a width-to-length ratio of at least 1 to 5 toprovide low RF impedance. Where two items are to be bondedthat must remain capable of movement by either turning,twisting, or partial rotation, a solid laminated or braidedtype strap shall be used. Properly shaped copper straps may beused for applications requiring moderate movements; berylliumcopper or phosphorous bronze <traps should be used for greatermovement. All bonding shall meet the criteria established byMIL-HDBK-419 .

5.6.4 Bond Resistance. Bonds for ground conductorswhose primary function is to provide a reference for powercircuits, electrical equipment, control circuits, signal

Icircuits, or to provide lightning protection shall have amaximum resistance of 1 milliohm or less. The resistanceacross joints, seams, or RFI seals in metallic members requiredto provide electromagnetic shielding shall also be 1 milliohm

1or less. Facility metallic structural members shall have amaximum bonding resistance of 10 milliohms or less betweenjoining members. Such structures shall include, but not belimited to:

a. Building metallic support structures.

b. Mechanical fixtures such as air conditioningducts, water lines, hydraulic lines, air lines,fuel lines, stairs, and railings.

2-)

MIL–STD–l542B (USAF)15 NOV 91

c. Metallic pipes, conduits, cable trays andsupporting structures.

d. Movable platforms, hinged doors, and othermovable devices.

5.6.5 Weltlinq. Structural steel members shall be weldedat least one place to joining members. If the reinforcing rodsare used as an equipotential plane, each rod crossinq shall bewelded.

5.6.6 B~ ilver SoIdering. Welding, brazing orsilver soldering shall be acceptable for the permanent bondingof copper and copper alloy materials for applications insidestructures. For external (outside) applications, includingbelow-earth level, welding shall be used. Alternate methodsrequire contracting officer approval.

5.6.7 B rid-n~. Either brazing orexothermic welding shall be used for the permanent bonding ofcopper conductors to steel or other ferrous structural members.

5.6.8 s~l .u The structural steel andreinforcing steel rods of a structure, such as launch pads,facility buildings, tracking stations, and safety shelters,shall be bonded to the earth electrode ground subsystem locatedunderneath or near the facility.

5.6.9 M a Pa~. Metal passageways shall bedesigned to provide a maximum dc resistance of 50 milliohmsbetween any two points on a passageway.

5.6.10 Facility Struttural Steel. The structuralframework and reinforcing steel shall be bonded to provide asingle homogeneous construction with a maximum dc resistance of50 milliohms between any two points of the interconnectedstructural members.

5.6.11 Movable Metallic Itema. Movable articles, suchas sliding equipment, movable platforms, metal doors, andhinged panels, shall be provided with flexible bonding strapsto ensure a maximum bonding dc resistance of 10 milliohmsacross any one bond.

5.6.12 B~q. Bonds shall be protectedagainst weather, corrosive atmospheres, vibrations andmechanical damage. Under dry conditions, a corrosionpreventive or sealant shall be aDDlied within 24 hours of=ssembly ofconditions,

the bond materials. ‘bnder high humiditysealing of the bond shall be accomplished

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immediately after joining. Each bonded joint shall beprotected against corrosion by assuring that the metals to bebonded are galvanically compatible. Bonds shall be paintedwith a moisture proof paint or shall be sealed with a siliconeor petroleum-based sealant to prevent moisture from reachingthe bond area. Bonds which are located in areas not reasonablyaccessible for maintenance shall be sealed with permanentwaterproof compounds. Iridited or other similarly protectedbonds do not require painting to meet the requirements of thisstandard.

5.6.13 CornDression Bonds in Protect ed Areas. Subject tothe approval of the contracting officer, compression bondsbetween copper conductors or between compatible aluminum alloyswhich are located in readily accessible areas not subject toweather exposure, corrosive fumes, or excessive dust may notrequire sealing.

5.6.14 Bondina Tests.

5.6.14.1 Facility BonfiinaTest. A bonding resistancetest shall be performed on all metal structures. Jointsrequiring bonding, whether by jumper or clamp-on metal-pressurefixture, shall be tested, but it is not necessary to test alljoints individually. The number and location of the facilitybonding tests shall be as approved by the contracting officer.

5.6.14.2 Bondina Joinks. All structural steel elementsshall be bonded and connected to the earth electrodesubsystem. The facility bonding test shall includemeasurements of these items. Critical bonding joints aredefined as those connecting sensitive electrical and electronicequipment enclosures, cable trays to and from these areas, andall protection subsystems (for fault currents and lightning)and their connections to ground.

5.6.14.3 Test Eauiument. An acceptable piece ofequipment for performing a test is the Shallcross Manufacturingco. low–resistance test set, Type 673A or 673D. Equivalentequipment may be substituted.

5.6.14.4 Test Procedure. Testing shall be performedduring all states of facility construction and subsysteminstallation. One lead of the test instrument shall beconnected to one bonded interface and the other lead connectedto an adjacent level. A second set of measurements shall bemade at the completion of construction to determine theOVer-.3ll resistance of various joints on the bonded structureto the nearest counterpoise stub-up connection. A random“proof of bonding integrity” test shall be required at

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29

r41L-sm-15426 (USAF)15 NOV 91

acceptance. The testing shall be performed in accordance withthe test procedures in MIL–HDBK-419. Periodic maintenanceinspection and testing shall be performed per MIL-HDBK–419. I

5.6.14.5 Success Criter ia. Any single critical jointmeasurement shall exhibit a dc resistance of 10 milliohms orless and the dc resistance from any point in the bondedstructure of the various control rooms to the nearest earthelectrode ground plate or rail shall be 100 milliohms or less.No single structural steel joint shall exceed a maximumresistance of 10 milliohms dc. Power, signal, control, andlightning subsystem bonds shall have a resistance of 1 milliohmor less.

5.6.14.6 Data Requiremen~. A record shall be kept ofthe measurements of all points made in each area. These recordsshall be coded so that any desired measurement point can berelocated easily for later verification. These records shallbe maintained for at least 5 years.

5.7 NATIONAL E I~.

Unless otherwise specified, the facility grounding,filtering, bonding, and shielding requirements associated with INational Security shall be in accordance with NACSIM 5203,NACSEM 5204, and MIL-HDBK-419. NACSIM 5203 refers toMIL-HDBK-419 for RED/BLACK signal grounding.

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MIL-sTD–1542B (USAF)15 NOV 91

SECTION 6

NOTES

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The contents of this Notes section are not compliant.The notes are intended for use by Government Acquisition

personnel for guidance and information only.

6.1 Im NDED USE

This standard is intended for use in acquisition contractsfor selected space system facilities. The requirements areapplicable to all related facilities including, but not limitedto, launch complexes, tracking stations, data processing rooms,satellite control centers, checkout stations, spacecraft orbooster assembly buildings, and any associated stationary ormobile structures that house electrical and electronicequipment.

Note that this standard would not normally be used in theacquisition of other types of facilities and equipment, such asLong Haul/Tactical Communications Subsystems (which areaddressed by MIL-STD-188-124). However, there may be othertypes of facilities and equipment, where the specialconsiderations stated in this standard would be applicable.For those facilities and equipment, a reference to theapplicable Provisions in this standard should be included inthe acquisition contracts. To avoid any possiblemisinterpretation, a statement should be included in thecontract for those facilities and equipment, that the words“space system facility” and “space equipment” in this standardare to be interpreted as the applicable system facility andequipment.

6.2 TAILORED APPLICATIOli

The requirements in each contract should be tailored to theneeds of that particular program. Military specifications andstandards need not be applied in their entirety. Only theminimum requirements needed to provide the basis for achievingthe program requirements should be imposed. The cost ofimposing each requirement of this standard should be evaluatedby the program office against the benefits that should berealized. However, the risks and potential costs of notimposing requirements shall also be considered.

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6.3 TOTAL OUALITY MANAGEMENT.

The intent of the design and construction requirements, andquality assurance requirements, specified in this standard isto assure that acceptable space facilities are acquired.In-process controls are almost always a more cost-effective wayof avoiding defects than the imposition of tests andinspections on completed units. Therefore, appropriatein–process controls and other total quality management stepsshould be imposed to achieve the high quality and reliabilitygoals required for space facilities. The testing requirementsspecified are intended to be the last step in assuring thequality of space facilities. When it has been thoroughlydemonstrated that the purpose of a testing requirement for anycharacteristic has been met by the in-process controls or othertotal quality management steps implemented by the contractor,the contractor may petition the contracting officer foraPProval to reduce the tests to sampling tests, or ifappropriate, for deletion of the test.

6.4 SUSJECT TERM (KEY WORD) LISTING

Air terminalsBond strapsBuildingsCable traysCathodic protectionEarth electrodeEarth resistivityElectrical powerElectromagnetic compatibilityElectromagnetic pulse (EMP)Equipotential planeFacility groundFacility powerFiltersGround Fault DetectionGroundingGround rodsHarmonic DistortionHigh frequency circuitsIsolationLightning protectionLightning rodsMultipoint groundPower distributionShielded enclosuresShieldingShielded rooms

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StructuresTechnical groundTechnical powerTransformers

6.5 SUPERSESSION DATA.

This issue of MIL-STD-1542B (USAF) is a complete revisionthat supersedes MIL-STD-1542A (USAF) for new designs. Changesin the text from the previous issue are indicated by a verticalbar in the margins. This was done as a convenience only andthe government assumes no liability whatsoever for anyinaccuracies in these notations. Bidders and contractors arecautioned to evaluate the requirements of this document basedon the entire content irrespective of the marginal notationsand relationship to the last previous issue. The previousissues remain in effect to cover previous procurements.

CustodiansAir Force - 19

Preparing ActivityAir Force - 19

(Project No. EMCS-F097)Document 2283b/Arch 1432b

33

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FrequencyFigure 10 - Detail of Typical Equipotential Ground Plane

for New Construction – HighFacilities Installation

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STANDARDIZATION DOCUMENT IMPROVEMENT PROPOSAL

lNSTRUCllONS

I. The preparing activity must complete blocks 1.2, 3. and 8. In block 1, both the document number and revisionletter should be given. . . . . .

2. The submitter of this form must complete blocks 4,5,6, and 7.

3. The preparing activity must provide a reply within 30 days from receipt of the form.

NOTE: This form may not be used to request copies of documents, nor to requert waivers, or clarification ofrequirements on current con~aa. Commenb submitied on fis form do not. ~on~”tme or imply authorization towaive any pom”on of the referenced document(s) or to amend contractual requwements.

FW%%%RNW% ‘“ ::.y,:1y4;; ~“~m2. DOCUMENT OATE (YYMMOOJ

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REASON FOE RECOMMENDATION

) Form 1426, Off B9 Previws cdiri.aru are dnoletc. ,,W90

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Documents

MIL-STD-1542B MILITARY STANDARD ... - zandz.com · MIL-STD-285 MIL–STD-461 MIL–STD–462 MIL-STD-463 ... NACE 1430 Broadway, New York, N.Y. Association of Std. RP–01-69 10018