DETECTION, MITIGATION, AND CONTROL OF CONCENTRIC NEUTRAL CORROSION IN MEDIUM-VOLTAGE UNDERGROUND CABLES
Institute of Electrical & Electronics Engineers
1 Overview
1.1 Scope
1.2 Purpose
2 Normative references
3 Definitions
4 Purpose of the concentric neutral wires
4.1 Path for flow of charging currents
4.2 Path for flow of fault currents
4.3 Reduce step and touch potential
4.4 Provide a system neutral
4.5 Types of concentric wires
5 Consequences of significant neutral corrosion
5.1 Cable failures caused by loss of metallic shield component
5.2 Improper operation of protective devices
5.3 Stray currents and interference
5.4 Effects on power quality
5.5 National Codes
6 Causes of neutral corrosion
6.1 Galvanic corrosion cell
6.2 Corrosion cell set up on a single metal
6.3 Soil corrosion
6.4 Differential aeration
6.5 Unintended or stray electrical currents
6.6 The coating of concentric neutral wires
7 Detection and evaluation
7.1 Visual inspection
7.2 Test concentric neutral using a time domain reflectometer (TDR)
7.3 Concentric neutral resistance measurement method
7.4 Surface voltage measurement technique
8 Control and mitigation
8.1 Cathodic protection using anodes and rectifiers
8.2 Cable replacement
8.3 Use of jacketed cable
8.4 Economic considerations with existing and new cable
Annex A (informative) Bibliography
Stresses on unjacketed, underground distribution cable installed direct buried or in conduit. The causes of corrosion in cable concentric neutral wires and straps and the methods available to detect this corrosion are described.
| Document Type | Standard |
| Status | Current |
| Publisher | Institute of Electrical & Electronics Engineers |
