Reliability-centred maintenance of 11KV switchgear

Switchgear

Item:

  • 11KV switchgear in a regional power distribution network
  • 75,000+ items of plant
  • 8 year “maintenance” cycle, costing approx. £1m per annum
  • No method in place for predicting possible failures
  • Difficult to incorporate into business planning

Objective:

  • Optimisation of switchgear inspection and maintenance, to reduce costs and minimise engineering disruption

Approach:

  • Analysis of failure incident reports by switch type, age, duty and failure mode – as data exist
11kV switchgear

Results:

  • Quantification of failure rates and reliability measures, for switch types with sufficient populations, as a function of age
  • Calculation of the effect on reliability of varying the maintenance interval
  • Calculation of the effect on reliability of different sampling levels for inspection, recognising that intrusive inspection can initiate problems
  • Insufficient data to identify any effects of duty or environment

Benefits:

  • Specification of initial inspection and maintenance plans, with rules for their continued optimisation as results are accrued
  • Considerable savings on inspection and maintenance costs
  • Understanding and control of system reliability

Publication:

Brear, J.M., Dean, R.J., Johnson, T.D. and Jones, G.T.
“Increasing condition monitoring to reduce unplanned outages and equipment replacement”
ERA Conf ‘Engineering Asset Management for Utilities, Industry and Commerce’
London, October 1999
 

Plant Integrity