Accession No

3826

Brief Description

framed label for Wh: 3827, by Department of Engineering, English, 20th Century (post-1933)

Origin

England; Cambridge; University of Cambridge

Maker

Department of Engineering

Class

electrical; physics

Earliest Date

1933

Latest Date

1980

Inscription Date

Material

wood; glass; paper; metal (brass)

Dimensions

length 325mm; breadth 241mm; depth 20mm

Special Collection

Provenance

Transferred from Dept of Engineering, University of Cambridge, Cambridge, England, 11/02/1992.

Inscription

see notes

Description Notes

Label to accompany Deptford cable piece. Glazed and in wooden frame. Label runs
‘The Ferranti Deptford Cable.
In 1890 S.Z. de Ferranti installed the first high voltage transmission system in this country. The system covered a route length of 7 1/2 miles and consisted of four twin concentric cables designed to operate at 10 kV.
The conductors were copper tubes of ordinary commercial dimensions and quality.
The insulating material consisted of brown paper which was dried and steeped in ozokerite, a waste product of candle manufacturing. The maximum dielectric stress was 12.5 kV/cm.
The cable was protected by a loosely fitting wrought iron tube and was sealed by basting with an asphaltic compound.
The cable was made in sections 20 ft. long so that in the four mains there were about 7000 joints, one of which is exhibited here. The joints account for about 18% of the resistance of the conductors.
The cables remained in use for more than 43 years, until the original 85 cycle Ferranti system was closed down on November 24th 1933.’

Condition fair (back in need of treatment); complete

References

Events