TECHNICAL BRIEFS - SYNOPSIS
|
| |
|
|
Failure mechanisms
Most failures of power cables are caused by external factors, primarily as a result of damage sustained during transport, handling, installation and later the misuse of these cables. On XLPE cable, water ingress as a result of mechanical damage, can lead to reduced life expectancy.
This is only a synopsis. For more information - please contact atnmarketing@aberdare.co.za
|
Antony Falconer PrEng
General Manager
Product Development & Application
Tel 011-456-4412
Fax 011-609-4739
e-mail afalconer@aberdare.co.za
|
|
| |
|
| |
| Drivers
Two major developments are driving the growth in OPGW installations. These are firstly the growth in IT bandwidth requirements and secondly deregulation of the telecommunications industry occurring all over the world. Municipalities look to establishing communication links with their distribution system and one way to do this is replacing existing pilot cable with OPGW or even to replace existing GW with OPGW. With deregulation utilities are seizing the opportunity to provide services to other service providers using their existing infrastructures and rights of way.
This is only a synopsis. For more information - please contact atnmarketing@aberdare.co.za
|
Antony Falconer PrEng
General Manager
Product Development & Application
Tel 011-456-4412
Fax 011-609-4739
e-mail afalconer@aberdare.co.za
|
|
| |
|
OPTICAL FIBRE IN POWER CABLES
|
USES
Optical fibres in power cables have numerous applications including voice, data transmission as well as cable temperature sensing to identify hotspots and possible problem areas before they manifest.
This is only a synopsis. For more information - please contact atnmarketing@aberdare.co.za
|
Antony Falconer PrEng
General Manager
Product Development & Application
Tel 011-456-4412
Fax 011-609-4739
e-mail afalconer@aberdare.co.za
|
|
| |
|
|
Overview
During the life of cables they are at their most vulnerable to damage whilst being installed. This damage could lead to immediate failure on being tested or energized but can also lead to reduced life expectancy of the cable. Premature medium term failure as a result of poor laying methods will cause serious inconvenience to users especially on sensitive installations. It is therefore essential that cable installations are performed by experienced reputable teams with best practice techniques and equipment.
This is only a synopsis. For more information - please contact atnmarketing@aberdare.co.za
|
Antony Falconer PrEng
General Manager
Product Development & Application
Tel 011-456-4412
Fax 011-609-4739
e-mail afalconer@aberdare.co.za
|
|
| |
|
|
|
ACCELERATED AGEING OF XLPE CABLES
For many years watertreeing has been recognized as a degradation process in medium voltage XLPE insulated cables, and is well documented. The facility has been designed with the flexibility to conduct tests to this as well as most internationally recognized test regimens. These include UNIPEDE, VDE and KEMA.
This is only a synopsis. For more information - please contact atnmarketing@aberdare.co.za
|
Antony Falconer PrEng
General Manager
Product Development & Application
Tel 011-456-4412
Fax 011-609-4739
e-mail afalconer@aberdare.co.za
|
|
| |
|
THE CHEMICAL RESISTANCE OF SHEATHING MATERIALS
|
General
There are three types of sheathing material generally used in power cables. These are flexible filled Polyvinyl Chloride (PVC), Polyethylene (PE) and halogen free Ethylene Vinyl Acetate (EVA) based. These materials provide the cable with different attributes for specific applications. From a cost point of view PVC and PE are very similar whilst EVA does have a significant cost impact.
This is only a synopsis. For more information - please contact atnmarketing@aberdare.co.za
|
Antony Falconer PrEng
General Manager
Product Development & Application
Tel 011-456-4412
Fax 011-609-4739
e-mail afalconer@aberdare.co.za |
|
| |
|
|
OVERVIEW
Certain environments are conducive to accelerated corrosion of metallic elements within power cables. The areas where such environments are encountered are well known to the corrosion protection industry. The Durban/Pietermaritzburg area, and the Richards Bay area are both good examples. The installation method and selection of cables to be used in these areas should take account of this corrosion environment.
|
This is only a synopsis. For more information - please contact atnmarketing@aberdare.co.za
Antony Falconer PrEng
General Manager
Product Development & Application
Tel 011-456-4412
Fax 011-609-4739
e-mail afalconer@aberdare.co.za
|
|
| |
|
CORROSION IN OVERHEAD CABLE
|
Galvanic corrosion
When two metallic materials are in contact in the presence of an electrolyte, conditions are ideal for galvanic corrosion to take place. Corrosion will increase on the least noble material (anode) and decrease on the noblest (cathode). The rate of corrosion depends on the potential difference between the materials, the surface area of the connected materials and the electrical resistance of the galvanic circuit.
This is only a synopsis. For more information - please contact atnmarketing@aberdare.co.za
|
Antony Falconer PrEng
General Manager
Product Development & Application
Tel 011-456-4412
Fax 011-609-4739
e-mail afalconer@aberdare.co.za |
|
| |
|
"CLEAN" PAPER CABLE DESIGN
|
INTRODUCTION
Traditionally paper insulated cables have incorporated bitumen impregnated fibrous materials for bedding and serving. The design team at Aberdare thought this to be an antiquated approach, and sought cost effective alternatives to these materials, that provide the customer with added value.
This is only a synopsis. For more information - please contact atnmarketing@aberdare.co.za
|
Antony Falconer PrEng
General Manager
Product Development & Application
Tel 011-456-4412
Fax 011-609-4739
e-mail afalconer@aberdare.co.za
|
|
| |
|
CABLES IN FIRE SITUATIONS
A BRIEF SUMMARY OF ISSUES
|
| 1 Summary
Cables in fire situations is a complicated many faceted issue. It is not possible to accurately predict how cables will behave in fires due to the many variables involved. All a cable manufacturer is able to do is to conduct a series of specific scaled tests in a controlled manner and compare the performance of cable with different designs and materials. Different materials give the cable different attributes but all attributes cannot always be achieved together.
This is only a synopsis. For more information - please contact atnmarketing@aberdare.co.za
|
Antony Falconer PrEng
General Manager
Product Development & Application
Tel 011-456-4412
Fax 011-609-4739
e-mail afalconer@aberdare.co.za |
|
| |
|
|
INTRODUCTION
This document provides guidelines on the pulling of cables into trenches and ducts using pulling eyes and pulling socks. It also provides some pointers on what to be aware of during the pulling process.
This is only a synopsis. For more information - please contact atnmarketing@aberdare.co.za
|
Antony Falconer PrEng
General Manager
Product Development & Application
Tel 011-456-4412
Fax 011-609-4739
e-mail afalconer@aberdare.co.za |
|
| |
|
COURSE OF ACTION WITH REGARD TO CABLES SUBJECTED TO IMPACT DAMAGE
|
When it becomes known that a drum of electric cable has been dropped or suffered other similar impact, that drum must immediately be regarded as being of suspect quality, and the incident should be reported to the nearest commercial or factory Technical department.
In some cases the damage suffered by the cable is obvious. In other cases the cable may appear to be undamaged.
This is only a synopsis. For more information - please contact atnmarketing@aberdare.co.za
|
Antony Falconer PrEng
General Manager
Product Development & Application
Tel 011-456-4412
Fax 011-609-4739
e-mail afalconer@aberdare.co.za
|
|
| |
|
GRAPHITE COATED CABLES BEWARE!
|
"Graphite coated’ cables are not simply standard cables with graphite spread onto the outer sheath. ‘Graphite coated’ cables are required to undergo a sheath integrity test and are designed with material and radials specifically for that purpose. It should be noted that testing the sheath integrity on a cable not designed for that purpose will very likely cause serious damage to the cable. This brief provides some background to the requirements and techniques applicable to this type of cable.
This is only a synopsis. For more information - please contact atnmarketing@aberdare.co.za
|
Antony Falconer PrEng
General Manager
Product Development & Application
Tel 011-456-4412
Fax 011-609-4739
e-mail afalconer@aberdare.co.za
|
|
| |
|
|
When an electric motor is started, the current drawn during the run up time will exceed the normal full load current of the motor. The starting current can be up to 8 times the full load current, depending on the type of starter used and the motor.
Guidelines are given later in this report as to the magnitude of these starting currents.
This is only a synopsis. For more information - please contact atnmarketing@aberdare.co.za
|
Antony Falconer PrEng
General Manager
Product Development & Application
Tel 011-456-4412
Fax 011-609-4739
e-mail afalconer@aberdare.co.za
|
|
| |
|
REPORT ON THE DANGERS ASSOCIATED WITH D.C. TESTING OF XLPE CABLES
|
Discussion:
The first alternative, i.e. application of a high D.C. voltage for a long duration is being questioned internationally, as it may damage the cable, and does not yield satisfactory results. The second option is acceptable, but not many utilities or contractors have access to AC test equipment (AC test equipment is large and expensive – D.C. test equipment is small and cheap.)
This is only a synopsis. For more information - please contact atnmarketing@aberdare.co.za
|
Antony Falconer PrEng
General Manager
Product Development & Application
Tel 011-456-4412
Fax 011-609-4739
e-mail afalconer@aberdare.co.za |
|
| |
|
SOME THOUGHTS ON LV DISTRIBUTION SYSTEMS
|
|
A. EARTHING
PME AND MEN AS USED ON LV DISTRIBUTION SYSTEMS
The above abbreviations stand for "protective multiple earthing" and "multiple earthed neutral" respectively.
This is only a synopsis. For more information - please contact atnmarketing@aberdare.co.za
|
Antony Falconer PrEng
General Manager
Product Development & Application
Tel 011-456-4412
Fax 011-609-4739
e-mail afalconer@aberdare.co.za |
|
|
| |
|
SABS 0198: Part XIII – 1988
|
|
Extracts for information and convenience.
5.1 GENERAL.
The use of inappropriate or excessive test voltages or unsuitable fault location methods can damage XLPE cables. Cables that are particularly prone to damage during testing are those that have water trees and those that have a construction that differs from that specified in the 1981 and subsequent editions of SABS 1339.
This is only a synopsis. For more information - please contact atnmarketing@aberdare.co.za
|
Antony Falconer PrEng
General Manager
Product Development & Application
Tel 011-456-4412
Fax 011-609-4739
e-mail afalconer@aberdare.co.za
|
|
| |
|
TESTING OF OLD AND DAMAGED XLPE CABLES
|
|
Aberdare are frequently requested to retest old, and sometimes damaged electric cable. The usual reason is to provide some form of comfort to the client who is considering reusing or upgrading an old or damaged cable installation.
This is only a synopsis. For more information - please contact atnmarketing@aberdare.co.za
|
Antony Falconer PrEng
General Manager
Product Development & Application
Tel 011-456-4412
Fax 011-609-4739
e-mail afalconer@aberdare.co.za |
|
| |
|
|
|
BACKGROUND
Much use is made of covered conductor in South Africa, and indeed also in the rest of the world. It is the objective of this article to explain the advantages and limitations of this type of conductor compared to the alternative of using fully insulated cores.
This is only a synopsis. For more information - please contact atnmarketing@aberdare.co.za
|
Antony Falconer PrEng
General Manager
Product Development & Application
Tel 011-456-4412
Fax 011-609-4739
e-mail afalconer@aberdare.co.za |
|
| |
|
VELOCITY FACTORS FOR TDM (TIME DOMAIN REFLECTOMETRY) FAULT FINDING EQUIPMENT
|
|
The Velocity factor of a cable is the fraction of the speed of light (300 metres/ micro sec) that a wave travels down the given table type.
The Formula is:
| Permittivity is |
± 6.0 for PVC insulation |
|
± 2.3 for XLPE insulation |
|
± 3.5 for Paper Insulation |
This is only a synopsis. For more information - please contact atnmarketing@aberdare.co.za
|
Antony Falconer PrEng
General Manager
Product Development & Application
Tel 011-456-4412
Fax 011-609-4739
e-mail afalconer@aberdare.co.za |
|
|
| |
|
PD Scanning of XLPE Cores
|
|
INTRODUCTION
Partial discharge (PD) scanning of medium voltage XLPE cores commenced when Aberdare began manufacturing medium voltage XLPE cables in the late 1970’s. It has proved an invaluable aid in controlling the quality of XLPE core manufactured ever since, by immediately identifying any problems in the manufacturing process and feeding this information back to production to take corrective action.
This is only a synopsis. For more information - please contact atnmarketing@aberdare.co.za
|
Antony Falconer PrEng
General Manager
Product Development & Application
Tel 011-456-4412
Fax 011-609-4739
e-mail afalconer@aberdare.co.za
|
|
|
|