ELECTROMAGNETIC COMPATIBILITY AND GROUNDING REQUIREMENTS ...everyspec.com/MIL-STD/MIL-STD-1500-1599/download.php?spec=MIL_STD_1542... · Electromagnetic Compatibility and Grounding

NONMEASUREMENTSENSITIVE

MIL-STD-E42A (USAF)01 MAR 1988

SUPERSEDINGMI L-STD-1542Dated 15APR 1974

MILITARY STANDARD

ELECTROMAGNETIC COMPATIBILITY

AND GROUNDING REQUIREMENTS

FOR SPACE SYSTEM FACILITIES

AMSC N/A AREA EMCS

DISTRIBUTION STATEMENT A: Approvedforpublicrelease;distributionunlimited.

Downloaded from http://www.everyspec.com

MIL-STD-1542A (USAF)01 MAR 88

DEPARTMENT OF THE AIR FORCEWashington, D.C. 20360

MIL-STD-1542A (USAF)

Electromagnetic Compatibility and Grounding Requirements forSpace System Facilities

1. This military standard is approved for use within theDepartment of the Air Force, and is available for use by allDepartments and Agencies of the Department of Defense.

2. Beneficial comments (recommendations~ additions? deletions)and any pertinent data which may be of use in improving thisdocument should be addressed to:

USAF Space Division, SD/ALMP. O. BOX 92960Worldway Postal CenterLos Angeles, CA 90009-2960

by using the self-addressed Standardization DocumentProposal (DD Form 1426) appearing at the end of thisby letter.

Improvementdocument or

ii



CONTENTS

PAGE

1.

1.11.2

2.

2.12.22.3

3.

3.13.23.33.43.53.63.73.83.93.10

4.

4.14.24.34.44.54.6

5.

5.15.1.15.1.25.1.2.1-5.1.2.25.1.35.1.3.15.1.3.2

.

SCOPE* ...................*.*.*.........*..*** ● ***.**..

PURPOSE ...................**..* .*.****.....0.........APPLICATION ● ● ....● .● ....● .● ● .● .● ● *● ● *● ● .***... ● ...● ● .

REFERENCED DOCUMENTS ● ● ......● ● ...*...0.● ● .● ● .● .● ...● ...

GOVERNMENT DOCUMENTS ......● ..● ...● ..*● .● ● ............NONGOVERNMENT DOCUMENTS. ..● .......● ...*.....● ● *.● ● ...ORDER OF PRECEDENCE .....● .● ....● *● .● .*..● ..● ● ● ● ● .● ...

DEFINITIONS ...........................................

FACILITY .............................................SPACE SYSTEM FACILITY ......*........*.*.**......*....FACILITY GROUND NETWORX ................**............LOW FREQUENCY CIRCUITS. ..............................HIGH FREQUENCY CIRCUITS. .............................SINGLE POINT GROUNDING ............● ● ..................MULTIPOINT GROUNDING ...*.*...........*.*....**.......EQUIPOTENTIAL PLANE ...*.*...● ....● ..*..*.● .*...*....*TECHNICAL POWER ● ..*........*...*...*.................FACILITY POWER .......................................

GENERAL REQUIREMENTS. .................................

ELECTRICAL POWER CHARACTERISTICS .....................ELECTROMAGNETIC COMPATIBILITY ........................SHIELDING ...............................0. ● ..........GROUNDING ............................................ELECTRICAL BONDING ...................................FILTERING ............................................

DETAILED REQUIREMENTS. ................................

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

Technical Power ..................................Facility Power ...................................

Power Grounding ....................................Primary Utility Power ............................Secondary Power ..................................

1

11

3

345

7

7778899999

11

111111111212

13

1313131313141414

iii


Lnln

lndF+9i

.●●✎✎✎●●●●●✎✎✎●●

...●●✎●●●●●●✎✎●✎☛✎●✎✎●●●✎●

●●●●✎●●●●✎●●☛●●✎●✎✎●✎●✎●●✎

●●✎●✎●●✎●●✎●✎●●✎●●●✎●●●●✎●✎●✎●

●●✎●✎✎●✎●●●●●●✎✎●●✎●●✎✎●●✎●✎✎●

..

..

.●

0

●.

.0.0●.

.0●*

●*

●*

●*

●U

:$:g●.A

“*s

●W

●M

*●O

●C

..4

●S

●U

●W

..A

:5

●●●●●✎✎✎●●✎✎●✎✎●●●●●✎●✎

●✎●●✎●●✎●●●✎✎●●✎●●●✎☛●☛

.●✎✎✎✎●●●●✎●●☛●●✎✎●●●●✎●

●●✎●●✎✎✎●●●✎●●✎✎●●●●✎●✎✎●●✎✎●✟✎✎☛✎●✎✎●✎●●✎✌✎

**●●☛●●●●●●●✎●●✎●●●●●●●✎●●●●●✎●●●●●

●●✎●●✎●●✎●✎●●●●●✎●✎●●✎✎✎●●✎●✎●✎●✎✎✎

......●✎✎✎✎●●●●●✎✎✎●✎✎●✎✎●●●✎●✎✎●✎●●✎●✎✎

.●✎✎✎✎✎✎✎✎✎●●✎●✎✎☛●●●●●✎●●●☛●●✎●●●●●✎✎

.●●●●✎●✌✎☛●●●●✎●●●●✎

,●✎●●●✎●✎●☛●☛●0●●●.●

●●●✎✎●✎●✎✎●✎✎☛✎●✎✎✎●✎✎✎✎✎✎✎✎●●●✎●●●●●●

●●●●✎●☞✎●✎✎●●●●●✎●●✎●●●●✎✎●●✎✎✎●●✎●●●✎●●

....●✎●✎●9●●●●..●●●.●●●●●.●....●●..

.,#,.*●●●●✎●●●✎●✎●✎●●●✎●●✎●✎●✎✎✎✎✎●

●✎●●☛●●✎✎✎●●✎✎✎●●●●●●●●●●●●●✎●●✎✎●✎✎●●●✎

.●✎●●●✎✎●✎●✎✎✎‘●.●●●..●..●.●●.●●.●.●●.

●●✎✎☛✎✎●●●✎✎●✎‘..●●.●●●

.●●✎✎●✎☛✎●●☛●●✎✎✎✎●●●✎✎

..●✎✎●●✎✎✎●✎✎✎●●✎●✎●●●✎✎✎✎✎✎●✎

.●✎✎●☛●●●✎●●✎●‘..●.●.●●...●●..

●●●✎✎●✎✎●●●●●●✎●●●●✎●✎●✎✎●●●✎●✎✎✎✎●✎●✎✎✎

●●✎✎✎●✎✎●✎✎✎●✎●✎●●✎●✎●●●●✎

.●●●●●●✎●✌✎✎✎●✎✎✎●●●✎✎●●✎✎

●●●✎●●●●●●●●✎✎●✎●✎●●●✎●●●

●✎✎●✎✎●●✎●✎●✎●✎✎✎●✎●●●●●✎

●✎

✎✎

✎☛

✎✎

✎✎

●✎

●✎

✎✎

●☛

✚✛

●o

..~

●4J

.(W.$

4●

3cm

●.A

●U

4●

C●O

●W

:E

●al

●4J

.(IY

●h

●●●✎●✎✎✎●✎✎✎●●●●✎●✎✎✎✎✎✎✌✎✌✌✌✎✎✌✌✎0.

+...*......●☞✎●☞✎●✎●✎✎

,.,●✎✎●✌✎✌✎✌✌✌

●✎✎✎✎✎✎✎✎✎✎✎✎✎

.●✎✎✎✎✎✎●✎✎✎✎✎●✎●✎✎✎✎●✎✎✎✎✎✎✎✎

,...,...

......●●✎✎●✎●●✎✎

●L

O”

“E

●a)

●u

●L

O:?“n●

3●

W;●

al●

5●o

.L4

>./4v.*

●C

●O

.,#+

●●(n

.Ma

●OC

“V●C

mm

a)Wtl)

Mu

ois●

O●

C●

.#“a●

A

●tn(l13

●W

CO

Yu

●(DOW

●UIG.A4

●E

MU

in

&co

?+NmAN(-O

ti(wm

●*

●*O

*

d4”dFloJit4cw

mm

mw

.*.*,,

●,*,.*

Artd

d?+

?+rid

dr+

r-1A

l+●

.**..●

...*..

Cf)m

mm

mm

mm

mm

mm

mm

●*.*.,

●*...*

..

Inln

lnln

lnln

lnm

u)m

lnLnln

ln

Wln

mb

.,,.mmmrn

..**

l+,+

dd

,..,m

e-)i”o

m.,..

Inm

lnln

mw

lnu)l-mcn

....*

●.

rf)mm

mm

mm

..*..*●

!+444444

+mmqmtot-ajm

‘●

*..,,.

..

I-4d

l+l+

rir+l+

r-irid●

,*....

.V

;w’v

w=$srv

vvsr

.0.,...

..

..

tnln

lnm

u)ln

lnln

inln

ln,..0..

●..**

mm

lnln

lnm

ul

Inln

ln

,



CONTENTS

PAGE

5.4.1.10 Testing ● ........*....*.*........0.....0............ 195.4.1 .10.1 Resistance Measurements ......................... 195.4.1.10.2 Cathodic Protection ..● .● ● *● *● ● ● ● .● ● .***.● .● ● .● * 20

5.4.25.4.2.15.4.2.25.4.2.35.4.2.45.4.2.55.4.2.65.4.2.7

5.4.35.4.3.15.4.3.25.4.3*35.4.3.45.4.3.5.5.4.3.65.4.3.75.4.3.8

5.4.45.4.4.15.4.4.25.4.4.35.4.4.45.4.55.4.5.15.4.5.25.4.5.35.4.5.4

5.55.5.15.5.25.5.2.15.5.2.25.5.2.35.5.2.45.5.35.5.3.15.5.3.2

Facility Ground Subsystem ...0.00...*..*......... 20Facility Structure Ground Returns ............. 20Ground Feeders ..● ● .***...**...● ● .● .● ...● ● *● .● . 20Service Structures ● *....*.........*..*.*...... 20Service Structure Tracks. ..................... 20Launch Pad Structure .....0..*...**............ 20Passageways .*...*............0................ 21Security and Perimeter Fences ................. 21

Lightning Protection Subsystem. .................... 21Buildings and Structures .......● ...● ..● .....● .● .. 21Air Terminals (Lightning Rods) .................... 21ROOF and Down Conductors ● ....0...**.*............ 21Structural Steel .........**..............0... ● ... 21Waveguide Grounding ..***.*....................... 22Exterior Wires and Cables ........................ 22Bonds ● ..**.*. . . . . . . . ● *.***. .**. .-** ● .**.... ● ..*.. 22Lightning Transient Protection ................... 22

Fault Protection Subsystem ...*...*.......● ......... 22Genera 1*....*.....0........0.......0. ● **......*.* 22Conduit, Pipes and Tubes ........● .*..*........... 23Cable Trays or Raceways.. ........................ 23Wiring Enclosures ...............0..0.0........... 23

Signal Reference Subsystem (Technical Ground) ...... 23General ....*..● ............*.*..**. ● ....**....... 23Low Frequency Circuits ● .*.**.......0....*........ 24High Frequency Circuits .......................... 24Technical Equipment .....● ● ● ..● ● ....● .● .*......● .. 24

FILTERS ..................***......0.............*.... 24General ...*..*.......● ..*....*.*................... 24Requirements ..................*...*.*.............* 25

Filters ...............*....*..*..* ● ....*......... 25Design ..........................=.=oooocoo=● =-*OO 25Fungus Resistance ................*............... 25Dissimilar Metals ........● .*..,..*.*............. 25

Test Requirements. ........................● ......... 25Qualification Testing.. .......................... 25Insertion Loss ............................● -.””.” 25

v


0$

N

.,●●●..●●●.●.●●●...●●●●......●*●●.●

iH!5uWVYgP4EH*A

●●●●✎●●●●●●●●

✎☛

✌●●●●●●✎✎●●●●●✎●✎☛●●●●☛●●●●

....●●✎✎✎✎✎●●●✎●✎✎●✎✎●●✎●✎●✎●●✎●●

.......●●●✎●✌●●●●●✎●●✎

●✎✎✎●✎●✎✎✎✎●●✎✎✎✎●✎●●✎

●●●●●●✎●●●●●✎●✎●✎●✎✎✎●●●●●●●●●✎

●●●●●●●●●●●●✎●✎●●●✎●✎✎☛●✎✎✎✎●●✎

●✎●●●✎●●✎✎●✎☛●✎✎●✎✌✎✎●✎✎●●✎●●●●●●●✎✎

●●✎●●✎✎✎●✎●✎●✎●●●●✎✎✎✎✎●●✎✎●●●●●●●✎✎

..

..

..

●☛

✎

●☛

☛

●☛

☛

✎☛

✎

✎☛

☛

●☛

☛

●☛

☛

●✎

☛

✎✎

☛

✌✎

✎

●☛

☛

●☛

☛

●☛

☛

●☛

✎

“,*”●

.*●

..

●*.

●*.

.*.,***m*

●E+

*.dd

.*@●

OW*fcJu●

*U●O

.(AO

●4J

●U

-

*●●●✎●✎●●●✎●✎●✎●✎✎✎●✎●✎●●●●●●●✎●●✌

..●✎✎●✎✎✎●●✎●✎●✎✎✎●●☛●●●●●

●●✎●✎✎✎●●●●✎●●✎●●✎●●☛●●●●✎

.●✎●✎●●●✎✎✎✎✎●✎✎✎✎●✎✎✎✎✎✎✎✎✎✎

.0.*..●.....●...●...●.6...●..

●,O

●**

.**

.**

●**

●**

..

.

..

.

●.*

●*.

..

.

..0.**

.**

*.*

●●::

.●

al●.

+.

..

“a●

●(V

.●

U●.

:%●

●U

●●O

●●

M*

●C4

:&c

●O.*

..#

●4JU

I

●●✎●●✎✎●●●✎✌✎●●●✎✎✎✌✎✎✎✎●●✎●

●●●✎✎●●✎✎✎✎✎●✌☛●●●✎●✎●✎●✎●✎●

●●✌●●●☛●●●●●☛☛✎●●●✎✎●●✎●●●●●●✎●●●●✎

.●✌✌☛✌●✎✎●✎●●✎●●✎●✎☛●✎●●●●●✎✎●✎✎●✎✎

.●●●●●●✎✎✎✎●✎●●●✎✎✎●●●✎●✎✎●✎●✎●●✎

.*.●●✎✎●●✎●✎✎✎✎●●●●●●●●✎●●●✎●●✎✎

.●✎✎●✎●✎✎●●✎✎●●●●●✎●✎●●●✎✌●✎●●●●

.●✎●✎●✎●●✎✎●✎●✎●●●✎✎●●●✎●✎●●●✎●●●●●●☛✎●●●✎✎

..

●✎

✎✎

✎✎

✎☛

✎☛

●●G

.al

●u

●tn.

..●

h●●

2

n

●C2

:2J

“*●UI

*W“4●

●A

●QI

●Q)

●+J

●CI2

●.4

.r+>●

JJ

●(n

●O

“*●*O●C

%!

●(U

●JJ

●H

:0

●

‘cd●

C13

‘D●

II

t-fm

a)a

)M

L4

~~

.rl.*

kh

3m.+h

de4fo

●.*.

Waw

w


MIL-STD-1542A (uSAF)01 MAR 68

CONTEXTS

PAGE

Figure 4 - Shielded Room Grounding. ......................... 36

Figure 5 - Details of Ground Rod or Earth ElectrodeSubsystem Installation. .......................... 37

Figure 6 - Connections to Earth Electrode Subsystem ......... 38

Figure 7 - Air Terminal Placement on Flat-roofed Structure. . 39

Figure 8 - fipical Fault Protective Subsystem ............... 40

Figure 9 - Elements of the Facility Ground Subsystem(with grid) ...........................=.....=*=ooo 41

Figure 10 - Typical Equipotential Ground Plane for NewConstruction High - Frequency FacilitiesInstallation. ...............*...*. ● ..*........ 42

vii


... _ .


THIS PAGE 1NTENTI0NALL% LEFT BLANK

viii



SECTION 1

SCOPE

1.1 ~SE

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

1.2 APPLICATION -

This standard is intended primarily for use in design andconstruction contracts for selected space system facilities.The requirements are applicable to all related facilitiesincluding, but not limited to, launch complexes, trackingstations, data processing roomsl satellite control c~nt~rs~checkout stations, spacecraft or booster assembly bulld~ngs, andany associated stationary or mobile structures that houseelectrical and electronic equipment. The requirements are notintended to be applicable to earth-based communication systemfacilities (see MIL-STD-188-124A).



THIS PAGE INTENTIONALLY LEFT BLANK

2



SECTION 2

REFERENCED DOCUMENTS

2.1 GOVERNMENT DOCUMEN=

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 SPECIF ICATIONs:

MIL-E-4158 Electronic Equipment Ground: GeneralSpecification For

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

MILITARY STANDARDS:

MIL-STD-188-124 Grounding, Bonding, and Shielding forCommon Long Haul/TacticalCommunications Systems

MIL-STD-220A Method of Insertion-Loss Measurements

MIL-STD-285 Attenuation Measurement forEnclosures, Electromagnetic TestPurposes, Method of

MIL-STD-461 Electromagnetic Emission andSusceptibility Requirements for theControl of ElectromagneticInterference

MIL-STD-462

MIL-STD-463

MIL-STD-889

MIL-STD-1541

Electromagnetic InterferenceCharacteristics, Measurement of

Definitions and Systems of Units,Electromagnetic CompatibilityTechnology

Dissimilar Metals

Electromagnetic CompatibilityRequirements for Space Systems

3



m LITARY HANDBOOKS:

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

OTHER GOVERNMENT DCXXJMENT~ :

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

NACSEM 5204 (C) Shielded Enclosures (U)

(Copies of specifications, standards, handbooks~ drawings~ and. publications required by contractors in connection with

specified acquisition functions should be obtained from thecontracting activity or as directed by the contracting officer.)

2.2 NONGOVERNME~ DOCUME~

The following documents forma 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.

National Fire Protection Association:

NFPA No. 70 National Electrical Code

NFPA No. 78 Lightning Protection Code

Application for copies should be addressed to:

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

National Association of Corrosion Engineers:

NACE Std. RP-01-69 Recommended Practice - Control ofExternal Corrosion on Underground orSubmerged Metallic Piping Systems.


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

4


MIL-STD-1542A (USAP)01 MAR 88

American National Standards Institute:

ANS1 C 84.1-1982 Power Systems - Voltage Ratings forElectric Power Systems and Equipment(60 HZ)


American National Standards Institute,1430 Broadway,New York, N.Y. 10018

(Nongovernment standards and other publications are normallyavailable” from the organizations which prepare or whichdistribute the documents. These documents also may be availablein or through libraries or other informational services.)

2.3 ORDER OF PRECEDENCE

In the event of a conflict between the text of this standardand the references cited herein, the text of this standard shalltake precedence. However, nothing in this standard shallsupersede applicable laws and regulations unless a specificexemption has been obtained.


MIL-STD-1542A (USAF)01 MAR88”

THIS PAGE IfiNTIONALLY LEFT BLANK.

6


.


SECTION 3

DEFIIUITIONS

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

3.2 J?ACILIT?(.

A facility is a building or other structure, either fixed ortransportable in nature, with its utilities, ground networks,and electrical supporting structures. All wiring and cablingthat is provided under terms of the facility contract areconsidered t-obe part of the facility. Any electrical andelectronic equipments required to be supplied and”installed bythe facility contractor are also part of the 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, or any combination.

3.3 FACKLITY GROUND *

The facility ground network is a network of conductors thatform direct low impedance paths between earth and various power,communications, and other equipments to effectively extend anapproximation of ground reference throughout the facility. Thefacility ground network is comprised of five subsystems asfollows:

a. Earth Electrode Sutivstem. The earth electrodesubsystem is a network of electricallyinterconnected rods, mats, or grids installed forthe purpose of establishing a low resistancecontact with the earth.

b. Licahtnina Protect j.onSubsvste . The lightningprotection subsystem is a lowmirnpedance path forlightning energy to the earth electrodesubsystem. It conducts the high currents awayfrom susceptible elements in the facility andlimits voltage gradients developed by the highcurrents to safe levels.

7



Ea=UaU2zwM subs=tem. .

c. The facility groundsubsystem is an electrically interconnected set ofground return conductors, conductive elements, andbonded structural elements that provide multiplecurrent paths to the earth electrode subsystem forfacility equipment (such as air conditioningequipment and ducts, heating equipment and ducts,lighting, electric motors, and the metalliccomponents of the structure). The facility groundsubsystem also includes the metallic components ofthe structure, the junction boxes, conduit, cableraceways, cable duct work, equipment racks,cabinets, pipes, and other norm-allynoncurrent-carrying elements in the facility.

d. Eauimnent Fault Protection.

Subs~stem. The‘equipment fault protection subsystem is a set ofground return conductors (green wires) thatprovide a current path to the earth electrodesubsystem of sufficient capacity so thatprotective devices (fuses and circuit breakers)can operate properly to protect personnel fromshock hazard and equipment from damage. .

e. sianal Reference Subsvstem (Teehnical Ground).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 both the signal and powercircuits for the technical equipment that isrelated directly to the military space system. Itmay consist of a low frequency grounding network(single point grounding), or high frequencygrounding network (multipoint grounding), or acombination of the two (a hybrid groundingnetwork). .

3.4 LOW FREOUENCY 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 PREOUENCY CIRCUITS .

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

8


._.


3.6 $INGLE POINT GROUNDING .

Single point grounding is a method of circuit and shieldgrounding in which each circuit or shield of the system has onlyone physical connection to a ground reference subsystem, ideallyat the same point for a given system. Single point grounding isused for low frequency circuits to prevent return currents fromflowing in structural elements. Power distribution circuitsutilize single point grounding.

3-7 ~*

Multipoint grounding is a method of circyit and shieldgrounding in which each circuit or shield of the system hasthan one path to a ground reference subsystem. Multipointgrounding requires the existence of an equipotential groundplane (See 3:8 and Figures 1, 2, 3 and 10). Multipleconnections are made to the equipotential plane for radio

more

frequency circuits by the sho~testt lowest impedance method=High frequency circuits utilize rnultipoint grounding.

3.8 EQUIPOTEN7X AL PLANE .

An equipotential plane is a flat mass of earth or metal(solid or grid) that offers a negligible impedance to currentflow so that differences in electrical voltage are minimizedacross the plane (see Figure 1 and 3). An equipotential planeis considered an earth ground for a signal reference subsystem(technical ground) regardless of its elevation from physicalearth.

3.9 TECHNICAL POWER .

Technical power is the electrical power supplied to signaland power circuits of technical equipment used for theoperational support of a military space system, such as:checkout equipment, test equipment, communications equipmentOand data processing equipment.

3.10 FACILITY POWER.

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

9




10



SECTION 4

GENERAL REQUIREMENTS

4.1 .ELECTRICAL P’OWER cHARAcTER~ .

When commercial electrical power quality or reliability isnot sufficient to meet the program needs, alternate methodssuch as dedicated power generation, power conditioning,uninterruptible power systems (UPS), or motor generators shallbe evaluated and utilized as required to meet the programneeds. Unless otherwise specified, the electrical power shallbe a DELTA-WYE configuration. ~

4.2 ELECTROMAGNETIC COMPATIBILIn.

Facility electrical and electronic subsystems andequipment shall be compatible with each other as well as withthe technical equipment installed in the facility for supportof space system operations. To achieve this goal with a highprobability of success requires the imposition of conductedand radiated EMI limits on the facility equipment.

4.3 ~HIELDING.

Shielding shall be provided as required for the protectionof circuits, equipment, and groups of equipment; forelectromagnetic compatibility within the system; and to complywith security (TEMPEST) requirements.

4.4 GROUNDING .

All space system facilities containing electrical andelectronic technical equipment shall have an earth-referencedfacility ground network. The facility ground network shallconsists of the following electrically interconnectedsubsystems:

a. The earth electrode subsystem.

b. The lightning protection subsystem.

c. The facility ground subsystem

d. The equipment fault protection subsystem.

e. The signal reference (technical ground)subsystem.

11



These items together constitute the total grounding system forthe facility (see Figure 2). The grounding of mobile facilitiesshall comply with the criteria of MIL-HDBX-419.

4.5 ELECTRICAL 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 impedance pathbetween them. This reduces the development of electricalpotentials between the interfacing surfaces for frequenciescapable of causing interference. Low resistance bonding shall beprovided as required for safety, for electromagneticcompatibility within the system, and to comply with security(TEMPEST) requirements. .

4.6 FILTERING.

Filtering shall be provided as required for the purpose ofestablishing electromagnetic compatibility, TEMPEST, or shieldedenclosure integrity. The design, performance, and testing of RFIfilters shall be in accordance with the requirements specified.

12



SECTION 5

DETAILED REQUIREMENTS

5.1 ELECTRICAL POWER.

5.1.1 Elec~~cal Po Characterxs~. .

wer Power qualityrequirements cannot be imposed on commercial power sources whenthese are utilized for space system facilities. Whencommercial power quality is not sufficient to meet programneeds, 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.

Voltage Regulation . AS percent no-load tofull-load with power factorranging from 1.0 to 0.8lagging

Frequency Regulation @ Hertz

Harmonic Distortion 5 percent total

Transients MIL-STD-461 Part 4

Distribution Voltage Standard commercial voltagesin accordance withANSI C 84.1 shall beutilized, but not less than480 volts.

5.1.2 El r-~er D~str~bution

5.1.2.1 Technical Power. The technical power feedersfrom the main power distribution point shall be isolated byseparate transformers from facility power feeders. Facilitiesthat have multiple users of technical power shall provideseparate step-down transformers at each users load (or byagreement the user may provide his own transformer). Usertransformers shall be the isolation type. Technical powercharacteristics shall comply with MIL-E-4158.

5.1.2.2 Facilitv Power. Facility power feeders from thefacility main power distribution point shall be separate fromtechnical power feeders.

13



5.1.3 Power Groundinq.

5.1.3.1 Primary Utilitw Power. Primary power shall not begrounded except at the neutral of the secondary of the subs~stemtransformer, as required by the National Electric Code.Transformers shall be of the isolation type (i.e., primarywindings mechanically and electrically isolated from the secondarywinding), with electrostatic shielding incorporated. Transformersshall be DELTA-WYE. Ground side switching shall not be used.

5.1.3.2 .Secondaw Poweq. Secondary power that is convertedfrom primary utility power shall have dc resistance isolation of 1megohm between the secondary and primary power. The varioussecondary power subsystems shall have dc resistance isolation of 1megohm between each other.

5.1.3.3 Ground Fault Circuit Interrupters. Receptacleoutlets for 120-volt single phase (15- and 20-ampere) shall haveground fault circuit interrupters (GFCI) where required forpersonnel protection or by NEC Articles 210 and 215.

5.1.3.4 Power Sources. Rotary or other power sources shallhave their frames and cases bonded to the facility groundsubsystem. Unbalanced loads should be avoided as far as possible,especially in electronic power supplies. All load lines shall betwisted.

5.1.3.5 Thermostats and Heaters. The control of primarypower by a thermostat is permitted only through a relay; the relayshall be suppressed and shielded. The relay and thermostat caseshall be referenced to the facility ground subsystem. The metalcase of the associated step-down transformers shall also bereferenced to the facility ground. Connections between athermostat and the control relay shall utilize a shielded twistedpair of wires, with the shield grounded at both ends. The shieldshall not be used to carry current.

5.1.3.6 Small Power Tools. Small power tools shall have acase ground connection provided from the tool chassis to the wallreceptacle.

5.1.3.7 ShoD Equiument. All items such as motor caseequipment frames shall be bonded to the power ground in accordancewith requirements stipulated in MIL-H-DBK-419. “

5.1.3.8 Voltaue Regulators. Electronically-controlledvoltage regulators and transformers used for voltage regulatingshall have their frames and cases bonded to the facility groundsubsystem. All regulated power load lines shall be of thestandard twisted type.

14

,



5.1.3.9switch, gear

Po er control and Switchina Eaui~ment. All powermotor, and control center distribution panels shall

be bonded, shielded, and grounded to provide the maximumattenuation of radiated interference. All metal parts shall bebonded to the facility ground subsystem; in addition, all ~openings (access or ventilation) shall be covered with 60-meshsteel screening. Where two items are to be bonded that mustremain capable of movement by either turning, twisting, or .partial rotation, a solid laminated type strap shall be used.Properly shaped copper straps may be used for applicationsrequiring moderate movements; beryllium copper or phosphorousbronze straps should be used for more excessive movement. Allbonding shall meet the criteria established.by MIL-HDBK-419.

5.2 ELECTROMAGNETIC COMPATIBILI~.

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

Fixed and Mobile GroundFacilities Equipment (Class A3) Part 1 and 4

Noncritical Ground Areas(Class B - Shop Equipment) Part 1 and 7

Electrical Power Equipment(Such as generators and UPS) Part 1 and 9

5.2.2 C Testznq.

. Compliance with Paragraph 5.2.1requirements shall be determined by tests performed inaccordance with MIL-STD-462 or approved test plans.

5.3 SHIELDING.

5.3.1 General. Shielding shall be utilized along withother basic interference control measures such as filtering,wire separation, wire twisting circuit layout, spectrum control,and frequency assignment to achieve compatibility of equipment.The degree of shielding shall be determined by the systemsengineering process to meet the requirements of this standardand of the system.

,5.3.1.1 Wire Shieldinq.

I

5.3.1.1.1 General. A double, triple, or solid conduitshield shall be used where a single braided shield is notadequate. Shields shall not be used as intentionalcurrent-carrying conductors, except for RF transmission lines.

15



5.3.1.1.2 Grcmndinq. High frequency shields shall begrounded at both ends and at every point where a discontinuityexists in metal enclosures. Low frequency circuit shields shallbe grounded at one end only; at the source end forinterference-generating circuits and at the load end for -interference-sensitive circuits. The shield shall maintaincontinuity through metallic enclosures. High frequency shieldsshall be grounded circumferentially to or inside connectors orequipment enclosures with no discontinuities in the externalshield.

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

5.3.1.2 shielded EuuxPment.

Enclosures .

5.3.1.2.1 Materia&. Equipment shields shall beconstructed of materials that provide the required attenuationof electromagnetic interference. Materials shall be corrosionresistant and compatible as defined by MIL-STD-889.

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 electromagnetic compatibilityin their intended environment. Door sealing devices shallwithstand 1000 open-close cycles without maintenance and retainthe required attenuation. Beyond 1000 cycles, maintenanceprocedures and periodic testing to retain the requiredattenuation 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.

5.3.1.3 shielded Rooms.

5.3.1.3.1 General. Shielded rooms shall be provided whenrequired for the control of TEMPEST signals or to provide aquiet electromagnetic environment for operation or testing ofelectrical and electronic devices. Shielded rooms shall meetthe requirements of this standard as well as the.requirements ofAppendix B of NACSEM 5204 and Appendix O of NACSIM 5203. Theattenuation requirements of the shield room walls, doors, and

16



penetrations shall be appropriate to the application, or asspecified in the contract.

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 c,ontact. The cycling and maintenancerequirements of Paragraph 5.3.1.2.2 shall apply. .

5.3.1.3.3 Grou dinq. Internal and external grounding ofthe circuits and th~ shielded room shall be in accordance withFigure 4 and MZL-HDBK-419. High and low frequency groundingsubsystems inside the shielded room shall be welded to theinside of the shield room wall. The exterior of the room shallbe grounded to the earth electrode subsystem at multiplepoints. Cable size shall be in accordance with Paragraph5.4.2.2. .

5.3.1.3.4 Tra sformers a d Fxltezs.

. Transformers andfilters may be loc~ted on eit~er the outside or inside wall ofthe shielded room. The external .enclosures of these units shallbe bonded to the shield wall in either case.

5.3.1.3.5 Penetrat ions. Penetrations shall be made in amanner which meets the operational function while maintainingthe integrity of the R.F. shield. All shielded roompenetrations shall meet the requirements of Appendix B of NACSEM5204 and Appendix O of NACSIM 5203.

5.3.1.3.6 matity Assl&rance All seams and penetrationsshall be tested during construction to validate seam weldingquality by means of approved “sniffer” type testing equipment.

5.3.1.3.7 ?est inq. The shield attenuation testing shallbe performed in accordance with MIL-STD-285 and Appendix B ofNASIM 5204. Test frequencies and test point locations shall beas specified in the contract, or as approved by the contractingofficer. The receiving antennas shall be positioned andoriented for maximum signal pickup.

5.4 GROUNDING.

5.4.1 Earth Electrode Sub vstes m.

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 ensuing

17



damage 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 withMIL-HDBK-419.

5.4.1.2 Earth Resist.

ivitv Sur eyv The design of theearth electrode subsystem shall be ba;ed on an earth resistivitysurvey conducted at the site prior to the detailed design. Themagnitude of earth resistivities shall be measured andrecorded. Natural features such as rock formations andunderground streams, as well as man-made features that have aneffect on earth resistivity, shall be recorded. This data shallbe documented as a part of the facility design data.

5.4.1.3 Resistance to Earth. The dc resistance to earthof the earth-electrode subsystem shall not exceed 10 ohms.Where 10 ohms cannot be obtained with the basic electrodeconfiguration due to high soil resistivity, rock formations, orother terrain features, alternate methods for reducing theresistance to earth shall be considered. These considerationsinclude, but are not limited to, 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.

This Standard, MIL-HDBK-419 and MIL-STD-188-124A do notrecommend the use of deep wells for the achievement of lowerimpedance to earth. Deep wells do achieve low dc resistance buthave very small benefit in reducing ac impedance. The objectiveof the earth electrode subsystem is to reduce potentials betweenand within equipments.

If a separate power source (substation) earth electrodesubsystem is utilized, the resistance to earth shall not exceed10 ohms. MIL-HDBK-419 provides further information on earthelectrode subsystems design. ,

5.4.1.4 Earth Electrode Subsystem Confzauration. 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. The

18


.

P41L-STD-1542A (USAF)01 MAR 88

rods shall be interconnected with number 4/0 AWG (American WireGage) bare copper cable buried at least 0.6 meters (2 feet)below grade (see Figure 5 and 6). The interconnecting cableshall be welded to each ground rod and close on itself 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 Ground Rods. 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 thickness. The thickness ofthe copper jacket shall not be less than 0.3 millimeters (0.012inches) . If deeper rods are required to meet the earth

. resistivity requirements of Paragraph 5.4.1.3, threaded rodextensions of the same specifications may be used. Extensionjoints shall be welded.

5.4.1.6 Connecting Risers. The lightning downconductors, the signal reference subsystem, and the faultprotection subsystem shall be welded to the earth electrodesubsystem. The risers (vertical conductors) shall be number4/0 AWG bare copper cable (see Figure 6 and 7).

5.4.1.7 Power Transformer Groundinq. Utility powershall be grounded only at the neutral of the secondary of thesubsystem transformer as required by NFPA 70.

5.4.1.8 Ground Isolation. The signal referencesubsystem,or technical ground, and the facility ground subsystem shall beisolated from each other except at connection to the earthelectrode subsystem. Isolation shall be maintained between thefacility ground subsystem and the lightning grounds, except atthe single point of connection of each lightning down conductorto the nearest facility structural element (See Figure 3 and 6).

5.4.1.9 Cathodic Protection. Cathodic protection ofunderground pipes or structures shall be designed and installedin accordance with the guidance provided in MIL-HDBK-419 andNACE Standard RP-01-69. Cathodic protection subsystems shallbe isolated from the earth electrode subsystem.’

5.4.1.10 Testinq.

5.4.1.10.1 Resistance Measurements. The resistance toearth of the earth electrode subsystem shall be measured by thefall of potential method (see MIL-HDBK-419) during dry surface

19



soil 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. It is recommended thatresistance to earth measurements be made at least annuallythereafter under dry surface soil conditions. For additionaltest information, see MIL-HDBK-419.

5.4.1.10.2 Cathodic Protection. Cathodic protectionsubsystems shall be tested for compliance with the criteria andmethods established by NACE Standard RP-01-69.

5.4.2 Facilitv Ground Subsvsterq. A facility groundsubsystem that provides multiple current paths to the earthelectrode subsystem for facility elements shall be provided.Facility ground plates shall be provided as required.

5.4.2.1 Facilitv Structure Ground Returns. Facilitystructural elements shall be bonded together and grounded tothe earth electrode subsystem by”electrical ground returnconductors, facility ground plates, and conductive elementsthat provide multiple current paths to the earth electrodesubsystem. The ground return conductors for facility elementsshall be of minimum length. They shall not be designed tocarry operational current, except during certain casesresulting from fault conditions (See Figure 9).

5.4.2.2 Ground Feeder=. The cross sectional area of theground feeders shall be 2,000 circular roilsper running foot(3.32 square millimeters per meter) and shall not be smallerthan number 4/0 AWG.

5.4.2.3 Service Structures. Metallic structures, suchas service towers, umbilical towers, and cherry pickers, shallbe connected to the nearest facility ground plate by number4/0 AWG bare copper cable or tubing. The grounding cable-shallbe as short as possible and not exceed 30 meters (100 feet).

5.4.2.4 Service Structure Tr acks. The roll-back tracksshall be grounded by connecting a number 4/0 AWG bare coppercable o“rtubing to the nearest facility ground plate. Thegrounding cables shall be as short as possible and not exceed30 meters (100 feet). ,

5.4.2.5 Launch Pad Structure. The launch pad structureshall be electrically bonded in accordance with Paragraph 5.6and shall be grounded to the facility ground subsystem by anumber 4/0 AWG (minimum) bare copper cable. The groundingcable shall be as short as possible and shall not exceed 30meters (100 feet).

20



5.4.2.6 l?--= -s The homogeneous bonding of themetal network of thewint~rconnecting passageways shall be”grounded by connecting the network of a passageway to thenearest facility ground plate or rail by number 4/0 AWG barecopper cable. The grounding cable shall be as short as .possible and not exceed 30 meters (100 feet).

5.4.2.7.Xtv and P~encS“m . All security of

perimeter fences shall be grounded according to proceduresoutlined in MIL-HDBK-419 (See Figure 3).

5.4.3 Lia”htnina Protection SuM=teq.

.

5.4.3.i ~uild~ S~ Lightning protectionshall be provided for all space syste; facilities andstructures including, but not limited to, substationstechnical equipment buildings, towers. antennas, and masts.

5.4.3.2 Air Termxn~.

(Laa-a Ro~. .

. Air terminalsshall be designed and installed.in accordance with NFPA 78,MIL-HDBK-419, and Figure 7 of this Standard. Refer toMIL-HDBK-419 and NFPA 78 for air terminal placement onnonflat-roof configurations and to Figure 7 for air terminalplacement on flat-roofed structures.

5.4.3.3 Roof and Down Con3ctoW * The roof and downconductors shall be number 4/0 AWG and shall be spaced notless than 15 meters (50 feet) apart (see Figure 7). Roof anddown conductor spacings of Figure 7 also apply to nonflat-roofconfigurations. Down conductor bends shall have a radiusgreater than 200 millimeters (8.0 inches). Down conductorsshall be located external to structures. Each down conductorshall be connected to the structural steel at the base of thebuilding by welding, that in turn is connected to the earthelectrode subsystem by welding. A minimum of two conductivepaths shall exist between air terminals and the earthelectrode subsystem.

5.4.3.4 Structur 1 Steela Substantial metal structuralelements of buildings and tow;rs shall be acceptablesubstitutes for lightning down conductors provided they arebonded in accordance with Paragraph 5.6.5 and do not containsensitive electronic equipment. The air terminal cables shallbe welded or brazed to the peripheral steel cglumns of thebuilding. The bases of the steel columns shall be connectedto the earth electrode system by number 4/0 AWG bare coppercables.

21

I



5.4.3.5 Wave&de Groun~.

As a minimum, allwaveguides located external to b~ildings shall be grounded asfollows:

a. Waveguide to antennas shall be grounded to theearth electrode subsystem at three points: at theantenna, at the base of the tower, and at thewaveguide entry port.

b. Metallic supporting structures for waveguide shallbe electrically continuous and grounded to theearth electrode subsystem at all supportingcolumns using No. 6 AWG as a minimum.

5.4.3.6 terxor. Wixes and Caw .. Corrosion-protected

steel conduit shall be used for all external power or signallines to shield against lightning or lightning-induced currentsand voltages. Junction boxes shall be electrically bonded tothe conduit. The conduit shall be connected to the earthelectrode subsystem at each end, ?nd at intermediate points at15 meter (50 foot) intervals. The use of fiber optic cables toguard against lightning induced voltage is recommended forexternal signal circuits. If fiber optic cables are not used,the circuit protective devices of Paragraph 5.4.3.8 arerequired. Buried conductors not in conduit shall be protectedby guard wires of 1/0 bare copper placed 0.3 meters (1 foot)above each conductor or group of conductors. The ground wireshall be connected to the earth electrode subsystem at each end.

5.4.3.7 pond=. All bonds between elements of thelightning”protection subsystem shall be welded or brazed. Allstructural steel members shall be bonded to each other bywelding.

5.4.3.8 Liahtnina Transient Protect ion. All power andsignal circuits that may be damaged as a result of lightning-conducted or induced transients shall be protected againstpulses that have the characteristics as specified inMIL-E-4158. Information on voltage limitations and surgeprotecting devices is contained in MIL-HDBK-419. PowerLightning Arrestors shall be installed in accordance with thenational electrical code.

5.4.4 Eauinment Fault Protect ion Subsy-m -

5.4.4.1 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 thepower source so that the protective circuit breaker or fuse can

22



clear faulted current. To protect personnel and equipmentfrom hazardous voltages, all exposed metallic elements ofelectrical or electronic equipment shall be connected to theearth electrode subsystem by means of the green wire. Aground bus shall be provided in all electrical equipment “cabinets, power panels, and switch gear cabinets, and aseparate 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-liDBK-419. A typicalequipment fault protection subsystem conductor arrangement isshown in Figure 8.

5.4.4.2 Conduxt..

PIDes.

and TuQgE . Metallic conduit,pipes, and tubes shall be electrically continuous and shall begrounded to “the fault protection subsystem grounding network.All conduit, whether used for power, signal, or control wires,shall use lock nuts along with conductive lubricants toprovide continuous conductivity.. Conduit brackets and hangersshall be electrically continuous to the conduit and to themetal structures to which they are attached.

5.4.4.3 Cable Travs or RacewaVs. The individualsections of cable tray assemblies shall be electrically bondedto each other and to the structures that support them. Allcable tray assemblies shall be connected to the faultprotection system within 0.6 meters (2 feet) of each end ofthe run and at intervals not exceeding 15 meters (50 feet)along each run.

5.4.4.4 Wirina Enclosures . All electrical and electronicwiring, distribution equipment enclosures and.the frames ofelectrical equipment, such as motors and generators, shall beconnected to the fault protection subsystem ground network.

5.4.5 Sianal Reference subsvstem {Teehnj.calGroundl.

5.4.5.1. General. A signal reference subsystem, ortechnical ground, shall be provided at each facility in whichelectronic equipment is installed to provide the ground referenceconnection from the earth electrode subsystem to all signalcircuits in the technical equipment used for operationalsupport. Signal circuits are grounded to control static charges,control electromagnetic interference, and establish a commonreference for signals between sources and loads. Figure 2 is agrounding schematic showing a typical signal reference subsysteminvolving both high and low fxequency circuits. o Additionalinformation on the design of signal reference subsystems iscontained in Appendix B of MIL-STD-188-124.

23



5.4.5.2 Low Freguencv C~. .

. The signal referencesubsystem, or technical ground, for “1OW frequencY ~i9na~circuits (from dc to 30 kilohertz) shall be connected to theearth electrode subsystem at one point only (single point) andshall be configured to minimize conductor path length. Thisnetwork reduces stray currents (primarily 60 Hertz) whichminimizes voltage potentials between points on the facility.thus minimizing common mode interference between power andsignal circuits. For additional guidance, consult MIL-HDBK-419.

5.4.5.3 Hiuh E%ecfuen~ C~C?ax@. .

The signal referencesubsystem, or technical ground, for ~igher frequency signalcircuits (above 30 kilohertz) require an equipotential groundplane. Figures 1, 2, 3, 9, and 10 provide information ontypical equipotential ground planes and how equipment is to beconnected to it. The equipotential ground plane shall beconnected to “the facility structure at multiple points. Variousconfigurations can be used-based on the frequencies involved,such as copper grids, structural steel elements (Rebar), or flatcopper sheets that can be installed under or over equipment.Connections from technical equipment to the equipotential groundplane shall be as direct as possible and shall utilize lowimpedance ground straps. High frequency equipotential groundplanes shall be designed in accordance with MIL-HDBK-419.Modification of the high and the low frequency bands can be madewith approval of the contracting officer. Examples of hybridgrounding subsystems, with low and high frequency circuitscombined, are illustrated in the grounding diagram in Figure 2.

5.4.5.4 Technical E~mnent.

Technical ground platesshall be provided for technical ~quipment throughout thefacility. The technical ground plates shall be copper at least6.35 millimeters thick, 100 millimeters wide, and at least 150millimeters long (1/4-inch thick, 4-inches wide, and at least6-inches long) with holes for connecting equipment. Each signalground shall be connected to the technical ground by aninsulated copper cable meeting the requirements of Paragraph5.4.2.2. Signal grounding cables between the technicalequipment, technical ground plates, and the earth electrodesubsystem shall be insulated from building steel and othergrounds. Their connections to the earth electrode subsystemshall be at a single-point, readily accessible for inspection.Bonding techniques allowing quick disconnection shall be used.The ground system shall not be used to complete, a signal circuitbetween that equipment and other equipment.

5.5 FILTERS.

5.5.1 General. This section of the standard establishesthe requirements for RFI filters utilized for electromagnetic

24



compatibility (EMC), TEMPEST, or shielded enclosure inte9ritYand encompasses the design/ performance and testing of RFIfilters. Optical isolators meeting the performance requirementsof this standard are acceptable for monitoring control andcommunications circuits.

5.5.2 Requirements.

5.5.2.1 ~S. Filters shall be installed in allfeeder breakers at distribution panels that provide power to.EMI-sensitive equipment, or into rooms where such equipment isinstalled. The filters shall be part of the distribution paneland shall provide a minimum attenuation of 80 decibels (dB)between 100 kilohertz and 400 megahertz. Adequate filteringshall be provided between any source that generates interferencethat may be conducted into EMI-sensitive equipment areas.Filters used-in this application shall conform to MIL-F-15733.

5.5.2.2 Desian Filters shall be designed in accordancewith the requiremen& of MIL-F-15.733. The design shall includeprevention of underdamped resonant conditions with the source orload which would cause excessive voltages that can degrade thefilter elements. Additional performance requirements may bespecified in the contract.

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

.5.5.2.4 D-SS imilar Metal= ● Dissimilar metals, as defined

by MIL-STD-889~ shall not be used in contact with each otherunless protected against galvanic corrosion. When it isnecessary that dissimilar metals be assembled together, amaterial compatible with each shall be interposed between them.

5.5.3.1 Qualification Test i,ng. 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 of testreports of units of the same design.

5.5.3.2 Insert ion 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 per decade. Simulatedload impedances shall be used during the test. If loadimpedances are not known, estimates to be used shall be approvedby the contracting officer.

25


5.6 130NDING

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 not degrade with age by corrosion or other means.

5.6.2 Corrosxon Protect2d2n. .

Bonds shall begalvanically compatible as defi;ed by MIL-STP-889. Bondsshall be protected against weather, corrosive atmospheresvibrations, and mechanical damage if the possibility ofexposure to these environments exist where they are located atthe 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. RF bonds shall havea width-to-length ratio of at least 1 to 5 to provide lowimpedance.

S.6.4 Bond Resx~ance.

● Bonds for ground conductorswhose primary function is to provide a reference for powercircuits, electrical equipment, control circuits, signalcircuits, or to provide lightning protection shall have amaximum resistance of 1 milliohm. The resistance acrossjoints on seams or RFI seals in metallic members required toprovide electromagnetic shielding shall also be 1 milliohm orless. Facility metallic structural members shall have amaximum bonding resistance of 10 milliohms between joiningmembers. Such structures shall include, but not be limited to:

a. Building metallic support structures.

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

c* Metallic pipes, conduits, and cable trays.,

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

5.6.5 Welding. Structural steel members shall bewelded at least one place to joining members. If Rebar isused as an equipotential plane, each rod crossing shall bewelded.

26



MIL-STD-1542A (USAF)01 MAR88- “ .

5.6.6 Brazina and Silver Solde~.

Welding, brazing orsilver soldering shall be acceptable fo~ the permanent bondingof copper and copper alloy materials for applications insidestructures. For external (outside) applications, includingbelow-earth level, only welding shall be used.

5.6.7 Bondina of Comer to Steel . Either brazing orexothermic welding shall be used for the permanent bonding ofcopper conductors to steel or other ferrous structural members.

5.6.8 ~. 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 facility structure ground subsystemlocated underneath or near the facility.

5.6.9 Metal Passaue avs Metal passageways shall bedesigned to provide a ma~imu~ dc resistance of 50 milliohmsbetween any two points on a passageway.

5.6.10 F~ ● 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 Metallic Items. Metal items such as cable trays,supporting fixtures, electrical conduits, and metallic fuellines shall be bonded to each other to provide a maximumbonding dc resistance of 10 milliohms between any two metalinterfaces.

5.6.12 Movable Metallic Itema. Movable articles, suchas hinged panels, metal doors, movable platforms, and slidingequipment, shall be provided with flexible bonding straps toensure a maximum bonding dc resistance of 10 milliohms acrossany one bond.

5.6.13 Bond Protection. All bonds except those listedin 5.2.3.2 shall be suitably protected against weather,corrosive atmospheres, vibrations and mechanical damage. Underdry conditions, a corrosion preventive or sealant shall beapplied with 24 hours of assembly of the bond materials. Underhigh humidity conditions, sealing of the bond shall beaccomplished within one-hour of joining.

5.6.14 Corro sion Protection. 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 silicone

27



or 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.

5.6.15 Commzession Bonds.n Protected Areas Subject to

the 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.

5.6.16 Pondina Testi .

5.6.16.1’ F’acilitv Bond~na TeX.

A bonding resistancetest shall be performed on all metai structures. Jointsrequiring bonding, whether by jumper or clamp-on metal-pressurefixture shall be tested, but it is not necessary to test alljoints individually.

5.6.16.2 ~. Bonding joints consideredcritical are those containing sensitive electrical andelectronic equipment, cable trays to and from these areast andall protection subsystems (for fault currents and lightning)and their connections to ground. All structural steelelements, though not classified as critical, shall be bondedand connected to the facility ground subsystem. The facilitybonding test shall. include measurements of these items. Thenumber and location of the facility bonding tests shall be asapproved by the contracting officer

5.6.16.3 Test Eauimmeng. An acceptable piece ofequipment for performing a test is the Shallcross ManufacturingCo. low-resistance test set, Type 673A or 673D. Equivalentequipment may be substituted with the approval of thecontracting office.

5.6.16.4 Xest Procedu r~. Testing shall be performedduring all states of facility construction and subsysteminstallation. One lead of the test instrument should 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-all resistance of various joints on the bonded structureto the nearest counterpoise stub-up connection. A random“proof of bonding integrity- test shall be required atacceptance. The testing shall be performed in accordance withthe test procedures in MIL-HDBK-419.

28


MIL-STD-2542A (USAF)01W88” >

5.6.16.5 c~. .

s . No single critical jointmeasurement shall exhibit a dc resistance greater than 10milliohms and the dc resistance from any point in the bondedstructure of the various control rooms to the nearest facilityground plate or rail shall not exceed 100 milliohms. No singlestructural steel joint shall exceed a maximum resistance of 10milliohms dc.

5.6.16.6 Data Real=~=ks.

. 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 until area acceptance.

5.7 =EST’ SECURXT’X.

Unless otherwise specified, the facility grounding,“bonding, and shielding requirements associated with TEMPESTsecurity shall be in accordance with NACSIM 5203, NACSIM 5204,and MIL-HDBK-419. NACSIM 5203 xefers to MIL-HDBK-419 forTEMPEST grounding.

29


_ .. _.



30


SECTION 6

NOTES


The contents of this Notes section are not compliant.The notes are intended for use by Government Acquisitionpersonnel for guidance and information only.

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 electronic equipment.

Note that this standard would not normally be used in theacquisition of other types of equipment, such as terrestrialcommunications subsystems (see MIL-STD-188-124A). However, .there may be acquisition contracts for some other type ofequipment requiring the special requirements as stated in thisstandard. For those facilities and equipment, a statementshould be included in the contract or the statement of work thatthe words “space system facility” and “space equipment” in thisstandard are to be interpreted as the applicable system facilityand equipment.

6.2 TAILORED APPLICATIONN

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 pctential costs of notimposing requirements shall also be considered.

6.3 SuBJECT TERM {KEY WORD> LISTING

Air terminalsBond strapsBuildingsCable trays

31



Cathodic protectionEarth electrodeEarth resistivityElectrical powerElectromagnetic compatibilityElectromagnetic pulse (EMP)Facility powerFiltersGrounding

rGround rodsIsolationLightnihg protectionLightning rodsPower distributionShielded enclosures ‘ShieldingShielded roomsStructuresTechnical powerTransformersTEPXPEST

CustodiansAir Force - 19

Preparing ActivityAir Force - 19

(Project No. EMCS-F097)Document 1500b/Arch 1223b

32


VERTICAL RISERS SHALL 8E WELDED

\OR BRAZED TO PLANE

. .

1A PLANE SHALL BE BONDEDAND WELDED TO BUILDING

.STRUCTURE

MH

*-----

+EACH CROSSOVER SHALL BE BRAZED OR WELDED

i i ‘-,0~ II - PLANE SHALL BE WELDED OR BRAZED TO EARTH

~ - ~\\ELECTRODE SUBSYSTEM

( METAL PIPES ENTERING THE FACILITY

\ J SHOULD 8E GROUNDED AT THE FACILITY~- ENTRY POINT

Figure 1. Example of Equipotential Plane for New Construction


.. . . . . .

I’41L-STD-1542A(USAF)01 MAR 88

SERVICEDISTRIBUTION DISCONNECTINGTRANSFORMER MEANS

-l--,=,lTFFFilFR

‘w If--w’’”6*t? L

(

r -1ELECTRICALEOUIPMENT PIATE

●

?

n

u u

lrMIJLll 1 1

JGROUND PLATE

T

BRANCHGROUNO

PLATE

MAINGROUNOCABLE— GRADE LEVEL

EARTH ELECTRODEu SUBSYSTEM

,

Figure 2. Earth Referenced Facility Ground Subsystem

34


MIL-STD-1542A

(USAF)

01

MAR

88

\

\YA

flk!i/

,,/

f\-\

‘.\AwooMA/

b-\

35


TECHNICAL GROUNO PLATESISOLATED FROM STRUCTURE ~

CENTER POINT OFTRANSFORMER OUTPUT

CONNECTED TOSINGLE GROUND POINTBY SEPARATE CABLE ~

//////// //

ENCLOSURE

E k FACILITY GROUNO PLATESWELOEO TO STRUCTURE(muflipoinl groundfor high frequency ‘

POWER TRANSFORMER(delta connected prima~Y connected secondaty)

POWER LINE ISOLATEOFEED THRU ANO

\ELECTROMAGNETIC FILTER

SINGLE GfiOUNO POINTWELOEO TO SHELL

TCABLE (in conduit forprotectiononly)

,)

-

/////////////////// /

INCOMINGPOWER LINE

!

LOW RESISTANCE EARTH GROUNO

Figure 4. Shielded Room Grounding


w4

. .

GRADE LEVELv

a \ w\ \ 12 in.\\ \

24 in. \\\

v 2+b

410AWG

cWELO

COPPER SDBCCABLE

314 in. x 10 nCOPPER-CIAO ROO —

Figure 5. Details of Ground Rod or Earth Electrode Subsystem Installation


& TERMINALS . . STEEL STRUCTURALCOLUMN

#

,

i #, BRAZEO/EXOTHERMICf+ MAIN / , TO STEEL COLUMNS+~ GROUND + #

2T06H , DOWN CONOUCTOR4

1.11

,t

+##

T

(brazed or exothermlc weld)

WELD

Figure 6. Connections to Earth Electrode Subsystem

w


n

J1

IIIIiIII

Y%III

III II

..I

mm


.,

&lJTH ELECTROOE SUBSYSTEM*——— . -t

EOPT CABINET~CONTAINING AC.I

r+POWEREO EQUIPMENTOR OUTLETS ?-l

‘OWER DUCT (AC)

7L.

SOLE AC NEUTRAL GROUND

E

,N

.—

1-

SWITCHGEARCABINET

.BG -<1

II

I1.i

TO EACH CABINET

I NEOPT AC POWER PANEL m 4 G

MAIN ACPOWERENTRY

CABINH ,

LEGENO:- NEUTRAL BAR (AC)

- PROTECTIVE BUSS1 ~ - CONOUIT

‘ NOTE: AC PHASE AND NEUTRAL WIRES AND METAL-TO-METAL CONTACTS AREOMITTED FOR CLARITY, THE GREEN WIRE IS IN THE SAME ENCLOSURE ● - GROUNO ROD

OR CABLE WITH THE POWER CONDUCTORS

Figure 8. Typical Fault Protective Subsystem


I GREEN WIRE GROUNOCABLE.TRAYS BONDED

7 TO STRUCTUREI I

/&’# I ------— f

. ! n%--- I

!1 4 CABLE TRANSECTIONS\ ELECTRICAL SUPPORTING ~’

rcTm,PTllrJ. Qn,,lwn TnBONDED

c --q------------------ - -..

vStructuralCOLUMtIJS BONDED

I IY’X’ZZV )- / A$+7+ EQUIPMENT (BONOED TO [-------- -. .

cg

.@l

Figure 9. Elements of the Facility Ground Subsystem (with grid)



///

//

++JIR, APPWWAATELY4/oAwGsTRANoED

. ..

.. .

. . .. . ..1.5 m (5 It) LONG

. . .. . . . ...

... .

. .

.. . ... ......... .

..... ...”.”.... . ....... ....... . . .... ...... . . ..... ..... .............. .

STEEL WIRE MESH WITH30 cm (12 in.) SQUARES

G

15 cm (6 in.) ID .. .. . ............

CEMENT ASBESTOSCONDUIT WITH RISER CAP

REINFORCEMENTROD (weld [o wire mesh) 1

Figure 10. TypicalConstruction - High

Equipotential Ground Plane for NewFrequency Facilities Installation

42


STANDARDIZATION DOCUMENT IMPROVEMENT PROPOSAL(S&efnstrum”ons- ReverseStiie)

DOCl)MEN7 NUM8ER Z 00 CUMENT T)TLE ElectromagnetIc Compatibilityand Ground“MIL-STD-1542A(USAF) Requirementsfor SpaceSystemFacilities&NAMEOFSIJBMl~lNG ORGANIZATION 4.TYPE OF ORGANIZATION (Marh

❑ VENOOR

•1 USER

. AODRESS (S&u& CUY. Ststi. ZJPCode)❑ MAF4.FAfl . . . . ~

❑ OTRER@pedfy):

L PROSt.EM AREAS

a P~ Number U@ hrdlng:

b. Rocommaldod word-:

c RmuonIRstbuIo f- $konwmndmion :

;. REMARKS

=.~a.NAME OF SUBMITTER (Lint. Ffrs I. MI) - Oo~~ b. WORK TELEPHONE NUMBER (1Co&) - Options!

. MAIL}NG AOORESS CW?Wt. Cffy, State. ZIP Co&) - Ocniod S. DATE OF SUBMISSION (YYMAIDD)

nn ——— . ---PREvIOUS EO1710N H OSSOLETE.

-,


INSTRUCTIONS: h ● continuing effofi to make our +xiardktion bcumeots better, the DoDprovida this form for use in

Ubmitting co mmeots and suggestions for ~mprovernenkAllusenofmkx titivationdocuments are invited to prondesuggestions. 7%is form easy be detache4 folded along the lines indicated, t+ed aloag the loose edge (DO NOT STAPLE), sodmdhd. In bkxk 6, be u apecifk as possible Aout particular problem UCS8 cucb u wording which required ioterpretatio% wastoo dgi~ netrkth, 100em, unbiguo~ or wss incompatible sad give propooed wording changee which would slletite the~blems. *ter in bkck 6 SBY remarks oat related to ● spedfk parsgmph of tlto docume nt. If block 7 u filled ou~ anScklmw!edgement will be msiled to you within 90 days to let you know that your Commen ti were M!CeiVed and are &iiCoashnd.

NOZE: ~ form w Dot be used to KZ!C@e8t COpiU Of doctumn ~ nor to -requwt wai~ deviati+ 0? dadfktI .On of

-*- q*-@ on ~t -rib* Commen* submitted cm this fmm do not constitute or imply authorizationto waive say portioo of tho referenced domment{t)ortouaendcon~ m@mmmatA

•uA~~~ 9~7*4ssw

(Fotd donA thh lint]

{Fold alon# thic UJU)

OFFICIAL BuSINES?E~ALTY FOR PRIVATE USE =m

111111nNO POSTAGENECESSARYIF MAILEO

IN THEUNITED STATES

BUSINESS REPLY MAIL IFIRST CLASS PERMIT NO. 7SZSC WASM DC

I

●OSTAGE WILL BE PAID BY Ma vs. AIR FORCC

USAP SpaceDivision,SD/ALMP.O. BOX 92960Worldway Postal CenterLos Angeles, CA 90009-2960


Documents

ELECTROMAGNETIC COMPATIBILITY AND GROUNDING REQUIREMENTS ...everyspec.com/MIL-STD/MIL-STD-1500-1599/download.php?spec=MIL_STD_1542... · Electromagnetic Compatibility and Grounding