MILITARY HANDBOOK: GROUNDING, BONDING, AND SHIELDING FOR

9,19
MB ELECTRONIC EQUIPMENTS AND FACILITIES

812
stron

6362
ID Department of Defense

1998
rok

TABLE OF CONTENTS

CHAPTER 1- FACILITY GROUND SYSTEM

GENERAL .

APPLICATION.

DEFINITIONS .

REFERENCED DOCUMENTS.

DESCRIPTION.

Facility Ground System .

Grounding and Power Distribution Systems .

Electrical Noise in Communications Systems .

BONDING, SHIELDING, AND GROUNDING RELATIONSHIP .

GROUNDING SAFETY PRACTICES .

CHAPTER 2- EARTHING AND EARTH ELECTRODE SUBSYSTEM OBJECTIVES .

Lightning Discharge .

Fault Protection .

Noise Reduction .

Summary of Requirements .

RESISTANCE REQUIREMENTS..

General.

Resistance to Earth .

National Electrical Code Requirements .

Department of Defense Communications Electronics Requirements .

Lightning Require meats .

SOIL RESISTIVITY .

Typical Resistivity Ranges .

Environmental Effects .

MEASUREMENT OF SOIL RESISTIVITY .

Measurement Techniques .

One-Electrode Method .

TYPES OF EARTH ELECTRODE SUBSYSTEMS .

General .

Ground Rods .

Buried Horizontal Conductors.

Grids .

Plates .

Metal Frameworks of Buildings .

Water Pipes .

Incidental Metals .

Well Casings .

RESISTANCE PROPERTIES .

Simple Isolated Electrodes .

Driven Rod .

Other Commonly Used Electrodes .

Resistance of Multiple Electrodes .

Two Vertical Rods in Parallel .

Square Array of Vertical Rods .

Horizontal Grid (Mesh).

Vertical Rods Connected by a Grid

Transient Impedance of Electrodes .

Effects of Nonhomogeneous (Layered) Earth

Hemispherical Electrode .

Vertical Rod .

Grids .

MEASUREMENT OF RESISTANCE-TO-EARTH

Introduction .

Fall-of-Potential Method.

Probe Spacing .

Extensive Electrode Subsystems.

Test Equipments .

Three-Point (Triangulation) Method .

OTHER CONSIDERATIONS .

Surface Voltages Above Earth Electrodes .

Step Voltage Safety Limit .

Step Voltages for Practical Electrodes .

Flush Vertical Rod .

Buried Vertical Rod .

Buried Horizontal Grid.

Minimizing Step Voltage .

Heating of Electrodes .

Steady State Current .

Transient Current.

Minimum Electrode Size .

2.9 ELECTRODE ENHANCEMENT .

2.9.1 Introduction .

2.9.2 Water Retention .

2.9.3 Chemical Salting .

2.9.4 Electrode Encasement .

2.9.5 Salting Methods.

2.10 CATHODIC PROTECTION .

2.10.1 Introduction .

2.10.2 Protection Techniques .

2.10.3 Sacrifical Anodes.

2.10.4 Corrosive Atmospheres .

2.11 GROUNDING IN ARCTIC REGIONS .

2.11.1 Soil Resistivity .

2.11.2 Improving Electrical Grounding in Frozen Soils

2.11.2.1 Electrode Resistance .

2.11.2.2 Installation and Measurement Methods .

2.11.2.2.1 Electrode Installation .

2.11.2.2.2 Backfill .

REFERENCES .

CHAPTER 3- LIGHTNING PROTECTION SUBSYSTEM

THE PHENOMENON OF LIGHTNING .

DEVELOPMENT OF A LIGHTNING FLASH .

INFLUENCE OF STRUCTURE HEIGHT .

STRIKE LIKELIHOOD .

ATTRACTIVE AREA .

Structures Less Than 100 Meters High.

Cone of Protection .

LIGHTNING EFFECTS .

Flash Parameters .

Mechanical and Thermal Effects .

Electrical Effects .

Conductor Impedance Effects.

Induced Voltage Effects .

Capacitively-Coupled Voltage .

Earth Resistance .

BASIC PROTECTION REQUIREMENTS .

DETERMINING THE NEED FOR PROTECTION .

Strike Likelihood .

3.8.2 Type of Construction 3-26

3.8.3 Criticalness to System Mission 3-27

3.9 APPLICABLE CODES 3-27

3.10 REFERENCES 3-28

CHAPTER 4 - FAULT PROTECTION SUBSYSTEM

4.1 FAULT PROTECTION .

4.1.1 Power System Faults .

4.1.2 Ground-Fault-Circuit-Interrupter (GFCl) .

4.2 EARTH CONNECTION .

4.3 AC POWER LINE GROUND .

4.4 TEST EQUIPMENT .

4.5 REFERENCES .

CHAPTER 5- GROUNDING OF SIGNAL REFERENCE SUBSYSTEM

INTRODUCTION .

CONDUCTOR CONSIDERATIONS.

Direct Current Resistance .

Alternating Current Impedance .

Skin Effect.

AC Resistance .

Reactance .

Proximity Effect .

Resistance Properties vs Impedance Properties

Effects of Geometry .

Stranded Cables .

Rectangular Conductors .

Tubular Conductors .

Structural Steel Members .

SIGNAL REFERENCE SUBSYSTEM NETWORK CONFIGURATIONS

Floating Ground .

Single-Point Ground (for Lower Frequencies) .

Multipoint Ground (for Higher Frequencies) .

Equipotential Plane .

Types of Equipotential Planes.

Floating System .

SITE APPLICATIONS .

Lower Frequency Network .