MAINTENANCE OF LIGHT-STANDARDS - A CASE-STUDY

This paper discusses several strategies for the maintenance of light-s tandards, where each light-standard consists of n independent and iden tical lamps screwed on a lamp assembly. The lamps are subject to stoch astic failures, and must be correctly replaced if the number of failed lamps reaches a prespecified number m, a norm that is set by the loca l management to guarantee a minimum luminance. As lamps have an increa sing hazard rate and there is a fixed cost of hoisting the assembly, w e propose various variants of the m-failure group replacement rule whi ch have in particular an age-criterion to indicate which of the non-fa iled lamps must be preventively replaced at the time that the assembly is lowered for a corrective lamp replacement. We show how the optimal threshold age can be determined. It appears that this modification re duces the long run average maintenance cost of the Europe Combined Ter minals by approximately 8.3%.