C-IVI-1

Contents

• Overview
  • General data
• Lines
• Tower forms
• Tower details
• Examples
• Sources

Overview

C-IVI-1 is a 400 kV electricity pylon (steel lattice transmission tower) series. It was the chosen design (in its hot-rolled steel form) for the North South Interconnector (also known as the Tyrone to Cavan Interconnector), a forthcoming power line being constructed between the Republic of Ireland and Northern Ireland. The designation is a little unclear, and can be seen written as “CIVI-1”, “C-IVI-1” and “CIVI-I”. “IVI” is simply a visual description of the arrangement of the insulators on the suspension tower: vertical, V, vertical.

C-IVI-1 is extremely unusual in (based on existing material) having only a single design of angle tower, suitable for 30°, 60° and 90° angles.

C-IVI-1 is also unusual in that it has been designed for ACSR conductor, specifically 600 mm² “Curlew”, which is not the same Curlew as found in mainland Britain. British ACSR types are named after mammals, but 600 mm² “Curlew” ACSR is an ASTM (American Standard for Testing and Materials) type, and ASTM ACSR is named after birds. The conductor type is likely to have been chosen according to Republic of Ireland practice rather than UK practice.

General data

Contractor	ESB International
Found	– (pending)
Height (straight line tower)	32 m
Voltage	400 kV
Known conductors	Twin
Design conductor	600 mm² ACSR
Design earthwire	Keziah AACSR
Circuit count	Single
Maximum span	500 m
Maximum equivalent span	385 m

Lines

• North–South Interconnector (forthcoming)

Tower forms

None of the various documents that depict the towers indicate the tower extension. For the purposes of the North South Interconnector, the intermediate tower can range in height from 27 to 43 m. Although the 30°, 60° and 90° angle towers are depicted identically, the 30° and 90° towers have a height range of 29.2 to 36.2 m while the 60° tower can go down to 26.2 m. The diagrams below were manually traced from material showing what seems to be the standard height towers (with no height given at all). The angle tower shown is the shortest size (for 30° or 90°) of 29.2 m, while the intermediate tower is 5 m taller than the minimum height at 32 m; this corresponds with another document that suggests that 32 m is the standard intermediate tower height and the two towers have matching ground clearance.

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

Tower details

Examples

This will be out of range.

Sources

• North South Interconnector — SONI (see figures 5.2 and 5.3 for standard tower types)
• Typical tower outlines — EirGrid
• Turleenan - Kingscourt 400kV Project, Visual Assessment of New Tower Outline — EirGrid
• Meath-Tyrone 400kV Interconnection Development (gives the tower height as 32 m)