De Cambeyrac à Strasbourg : Quinze ans d'exploitation des groupes bulbes

Abstract

Tests on model and prototype bulb sets have shown their hydraulic performance to be roughly the same or slightly better than that of conventional Kaplan sets. Electrical losses are a little higher in bulb generators, but often with a lower temperature rise. After fifteen years of operating experience, bulb sets can be claimed to answer the purpose for which they were developed. For example :__ 1. Small bulb sets provide the only answer for the heads and discharges associated with very low-output applications. 2. The larger bulb sets have got over their 'teething troubles', which were mainly connected with electro-erosion, loss of insulation efficiency owing to pollution, sealing problems, bolted assemblies, and cavitation. Though these problems have also been experienced with other designs, they were sometimes more crucial on bulb sets. Bulb and Kaplan running costs appear to be comparable, but this can only be taken as a tentative estimate in view of the limited experience available with bulb sets compared to Kaplans; when the first bulb sets appeared, Kaplans had been operational for 40 years. It would appear, however, that the saving on investment cost associated with bulb units is not achieved at the plant operator's expense.