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CE PL3

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Overview

CE PL3 is a Central England scheme constructed using Blaw Knox towers. The CE PL3 type appears to be a brief precursor to PL4: PL4 appears to be largely the same design but with additional clearance between the top phases and the earthwire.

General data

Contractor Blaw Knox
Found England
Voltage 132 kV
Dates back to 1936–37 (drawings)
Conductors Single
Circuit count Single, double

Can be confused with

Lines

Known lines include:

A single D30 SEW tower can be found in Tir-y-berth, Wales, on a WGR line between Ebbw Vale and Upper Boat.

The single-circuit line from Stafford substation to (presumably, as the line is buried) Bushbury B–C substation in Wolverhampton uses line towers similar PL3 S2 mixed with PL1-style Blaw Knox angle tower. These are listed under SS-PL1 for now.

Tower forms

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

Single circuit

CE PL3 S2 SEW
CE PL3 S10 SEW
CE PL3 S30 SEW
CE PL3 S30 DEW
CE PL3 S60 SEW
CE PL3 S60 DEW

The single-circuit angle tower diagrams are traced from various lines as depicted on Google Street View, scaled to the vertical clearances used with PL3, PL4, PL16 and K1201. Due to unaccountable discrepancies even in distant views, these diagrams are only very approximate. The difference in crossarm bracing between S60 SEW and DEW is per the only known example of S60 DEW. No S10 DEW, ST or SST towers are presently known.

Double circuit

CE PL3 D2 SEW
CE PL3 D2 DEW
CE PL3 D10 DEW
CE PL3 D30 SEW
CE PL3 D30 DEW
CE PL3 D60 DEW

The only documented evidence to date is the drawings for D30 single and double earthwire. The remainder of the diagrams are speculative only. D2 DEW and D10 DEW are based on photographs of towers on Hartlebury Common, as they fit with the general understanding that the only difference is in the earthwire shield angle on the angle towers. D60 DEW is based on a poor quality historic photograph depicting a tower (from an angle) that seems to fit. D2 SEW is based on another historic photograph said to be CE PL3 type; another photograph from the same source depicts a tower resembling D30 SEW. D10 and D60 DEW are derived from the equivalent CE PL4 diagrams.

Examples

View full-size image
CE PL3 D30 DEW; photo courtesy Tom Gloag (CC-BY-SA)

Tower details

Crossarm width is the total width across the widest crossarm.

Type Source Height Base width Crossarm width
S2 SEW Enhanced tower bible 73′–3″ (22.3 m) 14′–0″ (4.3 m) 25′–6″ (7.8 m)
S10, S30, S60 (SEW) Assumptions 65′–3″ (19.9 m) ? ?
S10, S30, S60 (DEW) Assumptions 70′–9″ (21.6 m) ? ?
D10 SEW Assumptions 77′–9″ (23.7 m) 22′–0″ (6.7 m) 29′–6″ (9.0 m)
D10 DEW Assumptions 83′–3″ (25.4 m) 22′–0″ (6.7 m) 29′–6″ (9.0 m)
D30 SEW XM1276-41A 77′–3″ (23.5 m) 22′–0″ (6.7 m) 32′–0″ (9.8 m)
D30 DEW K1611-123B 82′–9″ (25.2 m) 22′–0″ (6.7 m) 32′–0″ (9.8 m)

The single circuit angle towers are assumed to have standard 49′–3″ bottom crossarm height and 12′–0″ between crossarms on the same side (per PL3 and PL4 double circuit and K1201), and a peak height of (per the double circuit towers) 4′–0″ for single earthwire and 3′–6″ for single earthwire.

See also