The Bhakra Beas Management Board (BBMB) has been forced to close unit number 3 of the left bank powerhouse of the Bhakra Dam due to turbine fault.
Though, the unit is under forced shutdown, following breakage of inner head cover liner of the turbine, officially the unit has been taken out for 90 days to carry out 'annual maintenance'. It may be mentioned that the unit numbers 2 and 5 of the left bank are already under shutdown due to delayed renovation and modernisation works.
According to sources, inner head cover liner of the turbine of unit number 3 was found detached from its original position owing to the shearing of all the fixing bolts on February 19. The vibrations are only checked manually. There is no record of vibrations at the time of shearing of bolts, as it is done manually by experienced staff. It may be mentioned that there is no way to record on-line vibrations, as no such monitoring system has been installed.
A senior BBMB official said it would take over 3 months to carry out the repair works. The dismantling and reassembly of the unit is a lot of work.
Last year in May, ten bolts of the unit's turbine were found sheared and were replaced by new ones. Again, during the annual maintenance in November last year, six bolts that had been replaced during previous maintenance were found sheared again; they were replaced once again.
According to sources, bolts made of normal mild steel were manufactured at the Nangal workshop and used last year; they have again got sheared. The original bolts were made of carbon steel. This time suitable quality of carbon steel bolts, as recommended by Hitachi, would be manufactured and used to avoid such breakdowns in the future, said the official.
The commissioning schedules of Bhakra left bank powerhouse units 2 and 5 have been repeatedly overshot. The units are under shutdown for renovation, modernization (R&M) and upgradation; the work was supposed to be completed within 12 months from the date of commencement of work.
The renovation and modernisation of two units of Bhakra left bank have been delayed by more than two years. These units are also likely to be commissioned in the next three months.
BBMB may not be able to supply full evening peak load power to partner states due to closure of these units.
BBMB member (Power) Ashok Thapar declined to comment on being contacted, saying he was busy in a meeting.