Switchgear standard updated

In August 2010 the Code of practice for the British Standard 6626 governing the maintenance of electrical switchgear and control gear was revised replacing the version issued in 1985.Tony Hill discusses the implications




The British Standard 6626 Maintenance of electrical switchgear and controlgear for Voltages above 1kV and up to and including 36kV - Code of practice has been revised and replaced the version issued in 1985.

For anyone who owns, operates or maintains High Voltage (HV) Switchgear this is one of the key documents to be used in developing asset management and maintenance policies. The changes from the 1985 standard reflect increased knowledge and take cognisance of best practice.

Whether you simply own a single 11kV circuit breaker of have multiple substations within your electrical network you are obliged to take note of this document together with a whole range of other documents. This article aims to examine the key changes to the British Standard (BS) and consider how this will affect owners, operators and maintainers.

Firstly it is worth noting that the BS is not a specification and should not be quoted as such in a tender document. The BS takes the form of guidance and recommendations, however I feel sure than non compliance from the BS would have to be carefully considered in any legal or contractual discussions.

Whilst perhaps obvious the new standard sates that asset owners have a responsibility to ensure they have a maintenance policy in place and that it is communicated throughout the organisation. Interestingly there is a reference to PAS55 (Asset management.

Specification for the optimised management of physical infrastructure assets). PAS 55 is getting a lot of interest from asset owners and shows promise to become a defacto world-wide specification for any organisations seeking to demonstrate a high level of professionalism in whole life cycle management of their physical assets.

Work is currently underway for this standard to achieve IEC (International Electrotechnical Commission) status. If you would like to learn more about PAS55 then The Institute of Asset Management website at: www.theiam.org. Many if not all of the UK Distribution Network Operators have adopted PAS55 as part of their Asset Management Strategy.



Clearer definition of maintenance Perhaps the most fundamental change to the standard is a clearer definition of maintenance into the three categories of breakdown, preventative often time based and maintenance based on condition monitoring. The BS implies that best practice is often based around combining these categories. In the section on condition based maintenance the use of techniques such as partial discharge testing, trip circuit timing and RCM (Reliability Centred Maintenance) are specifically identified as a key element to a risk management based approach to optimising performance.

There is a new section on Personal Protective equipment (PPE) and treatment of electric shock. The need to monitor owners operational performance and others experience and to feed this experience into the maintenance policy is clearly stated. This reference to me further reinforces the need of asset managers to ensure that they consider DIN (Dangerous Incident Notices), SOP (Suspension of Operational Practices) and NEDERS (National Equipment Defect Reporting Scheme) issued by the Energy Network Association. A good source of further information on this and the wider issues associated with HV Switchgear Maintenance is available within www.hse.gov.uk/PUBNS/ priced/HSG230.pdf" HSG230 which is freely available on the Health and Safety Executive website.

To reflect developing technology there are sections on Sulphur Hexaflouride (SF6) and on maintenance policy for the vacuum circuit breaker interrupters.

Although perhaps a minor item which may have been overlooked in setting maintenance policies is the recommendation that all functional interlocks are tested before equipment is put back into service. I would be interested to know how many operators adopt this policy.

For those undertaking a review of safety rules Annex B (Safety Rules) provides an excellent basis for initial benchmarking of your current rules.

In conclusion the new standard provides excellent advice both in terms of technical application but perhaps more importantly in adopting best practice asset management policies.



Tony Hill CEng FIET is UK Sales and Marketing Director for EA Technology ISI