AS/NZS 3835.2:2006

Earth potential rise - Protection of telecommunications network users, personnel and plant Application guide

Standards Australia

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1 - AS/NZS 3835.2:2006 EARTH POTENTIAL RISE-PROTECTION OF TELECOMMUNICATIONS NETWORK USERS, PERSONNEL AND PLANT...
4 - PREFACE
5 - CONTENTS
7 - SECTION 1 SCOPE AND GENERAL
7 - 1.1 SCOPE
7 - 1.2 APPLICATION
7 - 1.3 REFERENCED DOCUMENTS
9 - SECTION 2 DEFINITIONS
9 - 2.1 DEFINITIONS
9 - 2.1.1 DOG
9 - 2.1.2 Earth grid voltage rise (EGVR)
10 - SECTION 3 EPR AND GENERAL
10 - 3.1 DESCRIPTION OF EPR
11 - 3.2 SOME EPR HAZARD SITUATIONS TO CONSIDER
11 - 3.2.1 Telecommunications cables passing through a hazard zone
12 - 3.2.2 Telecommunications equipment installed inside a building which may have a hazardous EPR on its power earth
15 - 3.2.3 Voltage hazard relevant to telecommunications network
15 - 3.3 CONSIDERATION OF POWER UTILITY CONSTRUCTION PROPOSALS
16 - SECTION 4 EPR HAZARD VOLTAGE LIMITS
16 - 4.1 INTRODUCTION
16 - 4.2 RISK OF EPR HAZARD
17 - 4.3 AUSTRALIAN EPR HAZARD VOLTAGE LIMITS
17 - 4.4 BASIS OF AUSTRALIAN EPR HAZARD VOLTAGE LIMITS
18 - 4.5 NEW ZEALAND EPR HAZARD VOLTAGE LIMITS
19 - 4.6 BASIS OF NEW ZEALAND EPR HAZARD VOLTAGE LIMITS
20 - SECTION 5 ASSESSMENT OF EPR
20 - 5.1 EPR ASSESSMENT PROCESS
21 - 5.2 COMBINED EPR AND LFI EFFECTS
22 - 5.3 HAZARD CALCULATIONS IN SMALL INSTALLATIONS
22 - 5.3.1 General
22 - 5.3.2 EPR calculation
23 - 5.4 ELECTRODES
23 - 5.4.1 General
23 - 5.4.2 Primary electrodes
24 - 5.5 ESTIMATION OF EARTH FAULT CURRENTS
24 - 5.6 SURFACE VOLTAGE GRADIENTS
24 - 5.6.1 Earth resistivity known
25 - 5.6.2 Uncertainties in earth resistivity
26 - 5.7 LIMITS FOR APPLYING THE SIMPLIFIED CALCULATIONS
26 - 5.7.1 General
26 - 5.7.2 Non-hemispherical earthing systems
27 - 5.7.3 Multilayer earth resistivity effects
27 - 5.7.4 Conductors extending the EPR
28 - 5.8 EPR IN LARGE SUBSTATIONS
28 - 5.8.1 General
28 - 5.8.2 EPR calculation
28 - 5.9 EARTH SYSTEM IMPEDANCE
28 - 5.9.1 General
29 - 5.9.2 Aerial conductors
29 - 5.9.3 Underground cables
30 - 5.10 DETERMINATION OF PROSPECTIVE FAULT CURRENT (Initial estimate)
30 - 5.11 COMPUTER ANALYSIS
33 - SECTION 6 FIELD TESTS AND MEASUREMENTS
33 - 6.1 INTRODUCTION
33 - 6.2 OBJECTIVES OF FIELD TESTS
33 - 6.3 METHODOLOGY
33 - 6.4 CURRENT INJECTION TESTS
33 - 6.4.1 General
34 - 6.4.2 50 Hz high-current injection test
35 - 6.4.3 Off-frequency high-current injection test
36 - 6.4.4 Off-frequency low-current injection test
39 - 6.5 SELECTION OF THE APPROPRIATE INJECTION METHOD
40 - 6.6 CURRENT SOURCES
40 - 6.6.1 Maximum value
40 - 6.6.2 50 Hz high-current source
41 - 6.6.3 Off-frequency high-current source
41 - 6.6.4 Off-frequency low-current source
42 - 6.7 REMOTE CURRENT ELECTRODE
42 - 6.7.1 Injection earth electrode
42 - 6.7.2 Potential measurement reference earth electrode
43 - 6.8 MEASURING GRID IMPEDANCE
43 - 6.8.1 Small earthing system
43 - 6.8.2 Tower or conductive pole earth resistance measurement
44 - 6.8.3 Large earthing system (fall of potential method)
45 - 6.9 MEASURING SURFACE VOLTAGE GRADIENTS
49 - 6.10 INTERFERENCE ELIMINATION
49 - 6.10.1 50 Hz standing voltage
49 - 6.10.2 Induced voltages
49 - 6.10.3 D.C. interference
50 - 6.10.4 Harmonic interferences
50 - 6.11 INTERPRETATION OF RESULTS
50 - 6.11.1 Extrapolation to remote earth
53 - 6.12 CONSIDERATION IN CONJUNCTION WITH LOW FREQUENCY INDUCTION (LFI)
54 - 6.13 SAFETY PRECAUTIONS
55 - 6.14 COORDINATION
55 - 6.14.1 Purposes of coordination
55 - 6.14.2 Coordination of tests
55 - 6.15 SOIL RESISTIVITY
55 - 6.15.1 General
57 - 6.16 METHODS OF MEASUREMENT (WENNER AND SCHLUMBERGER ARRAYS)
57 - 6.16.1 Symmetrical line arrays
58 - 6.16.2 Advantages of Wenner array
58 - 6.16.3 Advantages of Schlumberger array
59 - 6.17 RESISTIVITY MEASUREMENT ANALYSIS
59 - 6.17.1 Earth resistivity interpretation procedure
60 - 6.18 INTERPRETATION OF RESISTIVITY MEASUREMENT
61 - 6.19 SOURCES OF ERRORS
61 - 6.20 EQUIPMENT AND INSTRUMENTATION
62 - 6.21 CALIBRATION OF EQUIPMENT
63 - SECTION 7 MITIGATION
63 - 7.1 INTRODUCTION
63 - 7.2 SCOPE OF MITIGATION
63 - 7.3 MITIGATION MEASURES APPLIED TO POWER SYSTEM PLANT
63 - 7.3.1 General
64 - 7.3.2 Design options for minimizing EPR problems
70 - 7.4 LIGHTNING PROTECTION AT TELECOMMUNICATIONS USER™s PREMISES
71 - 7.5 MITIGATION MEASURES APPLIED TO TELECOMMUNICATIONS PLANT
71 - 7.5.1 General
71 - 7.5.2 Telecommunications isolation equipment
77 - 7.5.3 Installation of isolation equipment
80 - 7.5.4 Other mitigation measures that may be applied to telecommunications plant
85 - 7.5.5 Other services entering or leaving a HV site or EPR hazard zone
85 - 7.5.6 HV and LV monitoring, metering, and control equipment using telecommunications services
86 - APPENDIX A - TYPICAL HAZARD ZONES
86 - A1 INTRODUCTION
86 - A2 SCOPE
86 - A3 TYPICAL EXTENT OF HAZARD ZONES
86 - A3.1 For Australia
86 - A3.2 For New Zealand
86 - A4 GUIDELINES FOR INTERPRETATION OF THE TYPICAL HAZARD ZONE
101 - APPENDIX B - EPR DANGER SIGNS-AUSTRALIA ONLY SIGNS FOR HV SITES AND COMMUNICATIONS CABLE PITS/MANHOLES
101 - B1 SCOPE
101 - B2 GENERAL
104 - APPENDIX C - BIBLIOGRAPHY

Abstract

Specifies recommendation and code of practice for the application of the EPR Code of practice for the protection of persons or plant prescribed in AS/NZS 3835.1.

Scope

This Standard is a guide to the application of the EPR Code of practice for the protection of persons or plant prescribed in AS/NZS 3835.1. This Standard is intended for personnel responsible for ensuring safety in a telecommunications service environment.