Page 208 - Handbook of Electrical Engineering

192 HANDBOOK OF ELECTRICAL ENGINEERING

line). BS5468 is similar to BS5467 but only applies to XLPE insulated cables in the same voltage
range. BS6746 specifies the requirements of PVC for insulation and sheathing of cables. BS6469
specifies factory-testing methods for insulation and sheathing compounds. IEC60227 and 60245 give
the manufacturing and factory testing requirements for PVC and EPR in insulated cables respectively,
for voltages up to 1000 volts.

9.3.1 Compositional Notation

A commonly used notation for indicating the main components within a power or control cable uses
abbreviations, listed from left to right, that represent the core and its surrounding components, e.g.
STR CU/EPR/CSP/GSWB/CSP. This list denotes the following:-

• Conductor is stranded copper, STR CU.
• Insulation is ethylene propylene rubber, EPR.
• Inner sheath is chlorosulphonated polyethylene, CSP
• Armouring is galvanised steel wire braid, GSWB
• Outer sheath is chlorosulphonated polyethylene, CSP

See Appendix A for abbreviations used in specifying cables.
There may be additional materials within the cable such as semiconductor screens for the core-
insulation interface; jute, hessian or bitumen for giving extra water resistance to the wire armouring;
bronze tape for repelling insects.

Some of the international standards that are frequently used in the specification of cables in
the oil industry are, BS801, BS2627, BS4066, BS5308, BS5467, BS5468, BS6234, BS6360, BS6387,
BS6469, BS6622, BS6724, BS6883, BS7622, BS7629, BS7655, BS7835, BSEN10257, IEC60227,
IEC60245, IEC60331, IEC60332, IEC60502, IEC61034, see Table 9.8 which summarises where
the standards are particularly suited to components within a cable. Appendix B gives the titles of
these standards.
It can be seen from the above examples that many standards can be used. In fact a particular
cable may have its various components specified from different standards. Some standards attempt
to cover all aspects of cables that are suitable for certain situations or industries e.g. BS6883 for
marine and offshore structures; BS5467, BS6622, IEC60502 for land based plants. Care should be
taken when preparing a purchasing specification for a particular project. It is necessary to avoid
requirements that may be conflicting between the international specifications that are quoted in the
project specification. Such conflicting requirements could lead to a cable that is unnecessarily difficult
to manufacture and expensive to purchase or replace. See also Chapter 19.

9.3.2 Conductor

The conductors are usually copper or aluminium. Aluminium is seldom used in the oil industry
because it work hardens during installation, has higher losses, has high volt-drop at rated current and
requires special attention during termination.