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Blaw Knox T2175

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Overview

T2175 is a 275 kV UK electricity pylon (steel lattice transmission tower) type. T2175 appears to have been designed by Blaw Knox around 1967 for the line between Dounreay and Beauly. Potentially it could have been used on an earlier line. Designation T2175 is taken from a set of Blaw Knox drawings captioned “North of Scotland Hydro Electric Board 275 kV Double Circuit Line Dounreay – Beauly”, contract DT/31, reference number T2175, drawn on various dates between 1967 and 1969. (L2 is T1011, L3 is T1120 and L3(c) is MT1120.)

T2175 is a derivative of L3 designed for heavier smooth-bodied 0.52″ SCA instead of L3’s twin 0.175″ SCA (0.52″ is marginally under 50% more cross section area than twin 0.175″). The line tower is the T1521 enhanced clearance tower rather than the original L3 version. The angle towers appear to be visually the same as L3 except that the crossarm bracing has been revised; insufficient data is presently available to be clear on precisely what was changed.

The Ground Engineering article Powering through dates Beauly–Dounreay to 1968; drawings for T2175 towers have been recovered dating to 1967.

The same towers are also used on the line between Foyers Substation and Knocknagael Substation, the latter being adjacent to Beauly–Blackhillock. This line uses twin conductor bundles of unknown conductor specification.

Can be confused with

General data

Contractor Blaw Knox
Found Scotland
Height (straight line tower) 125′–0″ (38.1 m)
Voltage 275 kV
Dates back to 1967–69 (drawings)
Conductors Single
Twin
Design conductor 0.52″ smooth-bodied SCA
Design earthwire 0.175″ SCA

Tower forms

The following diagrams are shown to scale at 12 pixels per metre:

T2175 D STD
T2175 D10 STD
T2175 D30 STD
T2175 D60 STD

Examples

View full-size image
T2175 D; photo courtesy Ian McAulay (CC-BY-NC)
View full-size image
T2175 D30; photo courtesy Ian McAulay (CC-BY-NC)

Both examples were taken just outside Wester Balblair (Baile a’ Bhlàir an Iar), across from Beauly substation.

Tower details

Crossarm width is the total width across the widest crossarm pair, measured between the centres of the conductor attachment points rather than to the end of the steelwork.

Type Source Height Base width Crossarm width Weight
T2175 D STD XM4451-5 125′–0″ (38.1 m) 23′–0″ (7 m) 43′–6″ (13.3 m)
T2175 D10 STD XM4451-13 119′–3″ (36.3 m) 25′–0″ (7.6 m) 30′–0″ (9.1 m)
T2175 D30 STD XM4451-18 119′–3″ (36.3 m) 25′–0″ (7.6 m) 35′–0″ (10.7 m)
T2175 D60 STD XM4451-23 122′–9″ (37.4 m) 33′–0″ (10.1 m) 38′–0″ (11.6 m)
T2175 DT STD XM4451-28 127′–0″ (38.7 m) 37′–0″ (11.3 m) 59′–6″ (18.1 m)
T2175 DTV45 STD XM4451-38 127′–0″ (38.7 m) 37′–0″ (11.3 m) ?

Source material

Drawings

Drawing no. Tower Drawing type Series Drawn Amended Originator Other numbers
XM4451-5 D (M42′–E60′) Key Erection Diagram & Drawing Schedule T2175 July 1967 Blaw Knox BK35/22450
XM4451-6 A D M42′ General Arrangement & Erection Diagram July 1967 28/02/1968 BK35/22451
XM4451-7 D (extensions) August 1967 BK35/22452
XM4451-13 A D10° (M24′–E84′) Key Erection Diagram & Drawing Schedule 18/08/1967 29/10/1968 BK35/22458
XM4451-18 D30° (M24′–E84′) 23/08/1967 BK35/22463
XM4451-23 A D60° (M24′–E60′) January 1968 29/10/1968 BK35/22468
XM4451-28 A DT (M36′–E48′) 14/11/1967 22/05/1969 BK35/22473
XM4451-38 A DTV45 29/04/1969 22/05/1969 BK35/22482