IEEE 635-1989 pdf free.IEEE Guide for Selection and Design of Aluminum Sheaths for Power Cables.
1.1 Purpose
The purpose of this guide is as follows
1)Outline requirements and establish design guidelines for the selection of aluminum sheaths for extra-high,high-, medium-, and low-voltage cables.
2) Establish basic installation parameters for aluminum-sheathed cables
3)Provide references to industry standards and codes incorporating design and installation requirements of aluminum-sheathed cables.
4) Provide a comprehensive bibliography of literature related to the subject.
1.2 Scope
IEEE 635 covers power cables incorporating aluminum sheaths, except those of the SF6 rigid-bus type.
4. Advantages and Limitations of Aluminum Sheaths
A cable designer or user should be aware of the merits and limitations of aluminum-sheathed cable and assign an order
of importance to each property to satisfy the requirements of the specific application where power cables are involved.
4.1 Advantages
4.1.1
The use of an aluminum sheath reduces the weight of the cable compared with those having other metallic sheaths, thereby simplifying installation and lowering shipping costs. Furthermore, longer pulling lengths are possible with reduced cable weight.
4.1.2
As a sheath, aluminum is characterized by high electrical conductance and consequently by high short-circuit capability. In addition, high conductance offers excellent protection against lightning.
4.1.3
Aluminum has very good mechanical properties, for example. hardness and fatigue resistance. Therefore, the possibility of sheath fatigue failure due to vibrations and movement induced by thermal cycling is minimal.
4.1.4
Aluminum has a higher yield point, higher tensile strength, and less creep by comparison with other more ductile sheathing iniaterials. These attributes veriniit fewer clainips for iiistallations iii tunnels or above grouiid. The high hoop strength of aluminum sheath is particularly important in pressurized cables, since it may permit a reduction in the number of stop joints and pressure tanks.
4.2 Limitations
4.2.1
Aluminum is a relatively active metal chemically, and care must he taken to provide adequate protection against corrosion.
4.2.2
Because of its rigidity, smooth aluminum-sheathed cable is more difficult to bend than corrugated aluminum-sheathed cable.
4.2.3
For jointing and terminating, aluminum sheath requires techniques different from those applicable to other commonly used metals, and retraining of splicing and terminating crews may be necessary.IEEE 635-1989 pdf free download.