NR RT/E/P/27143 ISSUE 1 PDF

Introduction

This Procedure covers the maintenance of Overhead Line Isolators, and the unit replacement of blade/fixed contact assemblies using B.R. Standard equipment.

Spares for some of the isolators covered in this Procedure are no longer available from the manufacturers. It has been decided therefore that when these isolators require extensive maintenance to the fixed/moving contact assembly and no replacements are available from Depot/Stores stock, replacements must be made using B.R. standard items supplied by Morris Line Equipment (M.L.E.).

The procedures to be followed are detailed under the relevant section for the type of isolator being considered.

The relevant inspections shall be carried out at intervals not exceeding six years but, where special circumstances apply, shorter intervals may be adopted at the discretion of the Area Electrification Manager (A.E.M.) or appropriate officer.

The A.E.M. or appropriate officer, will establish policy for site maintenance and/or unit replacement.

Previous maintenance records should be checked for any recurring faults and for length of service of particular units. A note should be made for particular attention on site.

A preliminary visual examination on site will include the following:-

a) Correctness and legibility of isolator number and position plates.

b) Security of isolator keys and key box.

c) Safety screens and markings, where fitted.

d) General condition with regard to corrosion, damage and overall cleanliness.

A list should be made of items requiring attention or replacement.

If motor mechanisms are fitted always ensure that they are disconnected from the output shaft before starting work and re-connected before leaving site. The remote operation of these units should be checked after work is completed.

Always check that the isolator is left locked in the correct position.

Grease to be used for lubrication and protection is Castrol Rustilo 431 (B.R. Cat. No. 27/3435) except for locks, where dry graphite powder shall be used.

Check limit stops where fitted (either in the operating gear or contact assembly) in conjunction with the final position and adjust where necessary, after adjustment or replacement of parts of the isolator.