B343 Network Rail Safety Advice NRA24-09

Operational Restrictions on use of FSKII Circuit Breakers

Issued to: All Network Rail line managers, safety professionals and accredited contractors
Ref: NRA24-09
Date of issue: 30/09/2024
Location: National
Contact: Dom Banham-Hall, Network Technical Head Distribution HV/LV (Acting)

Overview

• During Test before Earth of an isolation between Finnieston and Rutherglen in Scotland, it became apparent that one of the electrical sections was still live.
• Subsequent investigations have found that a Circuit Breaker, which is an ABB supplied FSKII Circuit Breaker (top photo), had failed in the closed position.

Failure Mode Detail
• The insulating part of the operating rod (left photo) had become detached from the metal drive rod (right photo).
• A failure of the operating rod in this manner leaves the Circuit Breaker's vacuum bottle sprung closed.
• Whilst this is the first time ABB have seen a failure of this nature and the FSKII is a widely used circuit breaker, further investigations are urgently underway to understand the extent of devices which may be affected by this defect.

• Whilst an investigation is undertaken, it is necessary to introduce restrictions on the use of ABB FSKII Circuit Breakers as detailed below.
• An update to this Safety Advice will be provided when more information is available.

Safety-Advice-NRA24-09-Operational-Restrictions-on-use-of-FSKII-Circuit-Breakers.pdf

×
B343 Safety Advice NRA24-09

Acknowledgement Slip

Date
First Name
Surname
Phone Number
Email Address
Company Division
Do You Have Any Questions? *
Acknowledgement