Standard
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AS/NZS 3835.2:2006
[Pending Revision]Earth potential rise — Protection of telecommunications network users, personnel and plant, Part 2: Application guide
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.
Published: 27/09/2006
Pages: 99
Table of contents
Cited references
Content history
Table of contents
Header
About this publication
Preface
1 Scope and general
1.1 Scope
1.2 Application
1.3 Referenced documents
2 Definitions
2.1 Definitions
3 EPR and general
3.1 Description of EPR
3.2 Some EPR hazard situations to consider
3.2.1 Telecommunications cables passing through a hazard zone
3.2.2 Telecommunications equipment installed inside a building which may have a hazardous EPR on its power earth
3.2.3 Voltage hazard relevant to telecommunications network
3.3 Consideration of power utility construction proposals
4 EPR hazard voltage limits
4.1 Introduction
4.2 Risk of EPR hazard
4.3 Australian EPR hazard voltage limits
4.4 Basis of Australian EPR hazard voltage limits
4.5 New Zealand EPR hazard voltage limits
4.6 Basis of New Zealand EPR hazard voltage limits
5 Assessment of EPR
5.1 EPR assessment process
5.2 Combined EPR and LFI effects
5.3 Hazard calculations in small installations
5.3.1 General
5.3.2 EPR calculation
5.4 Electrodes
5.4.1 General
5.4.2 Primary electrodes
5.5 Estimation of earth fault currents
5.6 Surface voltage gradients
5.6.1 Earth resistivity known
5.6.2 Uncertainties in earth resistivity
5.7 Limits for applying the simplified calculations
5.7.1 General
5.7.2 Non-hemispherical earthing systems
5.7.3 Multilayer earth resistivity effects
5.7.4 Conductors extending the EPR
5.8 EPR in large substations
5.8.1 General
5.8.2 EPR calculation
5.9 Earth system impedance
5.9.1 General
5.9.2 Aerial conductors
5.9.3 Underground cables
5.10 Determination of prospective fault current (Initial estimate)
5.11 Computer analysis
6 Field tests and measurements
6.1 Introduction
6.2 Objectives of field tests
6.3 Methodology
6.4 Current injection tests
6.4.1 General
6.4.2 50 Hz high-current injection test
6.4.3 Off-frequency high-current injection test
6.4.4 Off-frequency low-current injection test
6.4.4.1 General
6.4.4.2 Using an out-of-service power line
6.4.4.3 Using a temporarily installed overland circuit
6.5 Selection of the appropriate injection method
6.6 Current sources
6.6.1 Maximum value
6.6.2 50 Hz high-current source
6.6.3 Off-frequency high-current source
6.6.4 Off-frequency low-current source
6.7 Remote current electrode
6.7.1 Injection earth electrode
6.7.2 Potential measurement reference earth electrode
6.8 Measuring grid impedance
6.8.1 Small earthing system
6.8.2 Tower or conductive pole earth resistance measurement
6.8.3 Large earthing system (fall of potential method)
6.9 Measuring surface voltage gradients
6.10 Interference elimination
6.10.1 50 Hz standing voltage
6.10.2 Induced voltages
6.10.3 D.C. interference
6.10.4 Harmonic interferences
6.11 Interpretation of results
6.11.1 Extrapolation to remote earth
6.12 Consideration in conjunction with low frequency induction (LFI)
6.13 Safety precautions
6.14 Coordination
6.14.1 Purposes of coordination
6.14.2 Coordination of tests
6.15 Soil resistivity
6.15.1 General
6.16 Methods of measurement (Wenner and Schlumberger arrays)
6.16.1 Symmetrical line arrays
6.16.2 Advantages of Wenner array
6.16.3 Advantages of Schlumberger array
6.17 Resistivity measurement analysis
6.17.1 Earth resistivity interpretation procedure
6.18 Interpretation of resistivity measurement
6.19 Sources of errors
6.20 Equipment and instrumentation
6.21 Calibration of equipment
7 Mitigation
7.1 Introduction
7.2 Scope of mitigation
7.3 Mitigation measures applied to power system plant
7.3.1 General
7.3.2 Design options for minimizing EPR problems
7.3.2.1 Location
7.3.2.2 Earthing system design
7.3.2.3 Hidden power earthing systems
7.3.2.4 Impact of interconnected MENs and HV cable sheath bonding on EPR levels
7.3.2.5 Interconnection of distribution HV and LV earthing systems
7.3.2.6 Reduction of earth fault current
7.3.2.7 Use of an earthing transformer
7.3.2.8 Size of the earthing system and its effects on the EPR drop-off curve
7.4 Lightning protection at telecommunications user’s premises
7.5 Mitigation measures applied to telecommunications plant
7.5.1 General
7.5.2 Telecommunications isolation equipment
7.5.2.1 Isolating links
7.5.2.2 Isolation devices
7.5.2.2.1 General benefits of using isolation devices
7.5.2.2.2 Isolation transformers
7.5.2.2.3 Neutralizing transformers
7.5.2.2.4 Optic fibre isolation devices
7.5.3 Installation of isolation equipment
7.5.3.1 General
7.5.3.2 Recommended distances and clearances for isolation equipment
7.5.3.3 Materials used for construction and cable entry to isolation backboard or cabinet
7.5.4 Other mitigation measures that may be applied to telecommunications plant
7.5.4.1 Choice of isolation method
7.5.4.2 Telecommunications cables, conduits and ducts
7.5.4.3 Telecommunications cable pits, manholes, and chambers
7.5.4.4 Telecommunications earths
7.5.4.5 Telecommunications cable joints
7.5.4.6 Telecommunications cross-connection units
7.5.4.7 Telecommunications main distribution frames (MDFs)
7.5.4.8 Telecommunications exchanges
7.5.4.8.1 General
7.5.4.8.2 Telecommunications exchanges near HV earthing systems
7.5.4.8.3 Telecommunications exchanges with internal HV distribution substations
7.5.4.9 Telecommunications user terminal equipment
7.5.4.9.1 General
7.5.4.9.2 Standard telephone services
7.5.4.9.3 Private telephone meters
7.5.4.9.4 Public telephones (payphones)
7.5.4.9.5 PABX
7.5.5 Other services entering or leaving a HV site or EPR hazard zone
7.5.6 HV and LV monitoring, metering, and control equipment using telecommunications services
Appendix A
A1 Introduction
A2 Scope
A3 Typical extent of hazard zones
A3.1 For Australia
A3.2 For New Zealand
A4 Guidelines for interpretation of the typical hazard zone
Appendix B
B1 Scope
B2 General
Appendix C
Cited references in this standard
ESAA EG1(2000)
Substation earthing guide
[Current]
Degrees of protection provided by enclosures (IP Code) (IEC 60529:1989 (ED. 2.2) MOD)
[Pending Revision]
Earth potential rise — Protection of telecommunications network users, personnel and plant, Part 1: Code of practice
[Superseded]
Effects of current on human beings and livestock, Part 1: General aspects
Content history
DR 04472
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