Cable Developments

First gutta percha electric cable followed by rubber and vulcanised bitumen insulation

1880

In the 1880’s the first insulated cables were insulated with gutta percha, a natural latex material produced from the sap of trees of the same name. This insulation needed to be kept constantly wet or it would dry out and fail to insulate the conductors. This material was largely replaced by rubber and vulcanised bitumen.

Ferranti 10 kV tubular cable and the introduction of paper insulation

1890

In 1890 Ferranti developed the first oil-impregnated-paper power cable; following their manufacture, his cables were installed in London in 1891 for 10-kV operation. The cables were made in 20-ft lengths; as the total circuit was 30 miles in length about splicing joints were 4 required. Nevertheless, these cables performed so well that the last cable length was removed from service only in 1933.

Hochstadter development of screening which enabled distribution voltage to be increased to 33 kV

1914

High-voltage cables have additional internal layers in the insulation system to control the electric field around the conductor. These additional layers are required at 2,000 volts and above between conductors. Without these semi-conducting layers, the cable will fail due to electrical stress within minutes. This technique was patented by Martin Hochstadter in 1916 the shield is sometimes called a Hochstadter shield and shielded cable used to be called H-Type Cable.

Emanueli provided the principle of pressurisation with fluid-filled paper cables for voltages of 66 kV upwards

1926

PVC insulation first tried out in Germany

1930

In the 1920s and 1930s, synthetic materials such as PVC (polyvinyl chloride) and PE (polyethylene) began to be used for cable insulation. These materials offered superior electrical and mechanical properties compared to earlier materials, and they were also more resistant to environmental factors such as moisture, heat, and chemicals. PVC insulation was first introduced in the 1930s and became popular in the 1950s and 1960s

First 3-core 132 kV pressure cable in service

1943

The cable comprises a plurality of insulated conductors, each conductor having a central gas passageway and being gas permeable. The conductor is wrapped with tapes impregnated with an insulating oil, and the wrapped tapes are encircled by gas permeable layers and skid wires. Three of such insulated conductors are encircled by a gas impermeable pipe, and the pipe and the conductor passageways are filled with an insulating gas under pressure above atmospheric pressure

Introduction of the mass-impregnated non-draining cable in the UK to overcome the problems of drainage of oil-rosin impregnant with cables installed on slopes

1949

Full commercial introduction of PVC and later thermoset insulation for wiring cables PVC for power cables followed at the end of the decade

1950

Successful development of aluminium sheaths, initially for pressure-assisted cables,
and gradual adoption of aluminium conductors for power cables
First 275 kV FF cable (1954), operational use in 1959

Significant distribution economies obtained by the use of combined neutral and earth cables England/France +100kV submarine d.c. link inaugurated in 1961 First 400 kV FF cable, operational in 1969

1960

Metrication of British Standards

1970

Gradual extension of the use of thermoset insulation, mainly XLPE, as an alternative to paper insulation

1970

Large commercial applications up to 15 kV but also experimental
installations at higher voltages including transmission up to 132 kV

Introduction of optical fibre into overhead lines Very widespread use of XLPE in the 11-33kV range with significant quantities installed for transmission voltages of 66-240 kV

1980

Discovery of high temperature superconducting materials
Development and growing use of cables designed to alleviate the effects when cables
are involved in fires; properties include reduced flame propagation, low smoke
emission, reduced emission of noxious fumes and corrosive gases and combinations of
these characteristics

Widespread use of optical fibres in overhead lines Extension of polymerics to EHV and the commercialisation of PPL Practical demonstrations of superconducting cables

1990