Mechanical refurbishment of Manapouri hydro turbine and generators. Manapouri has 7 by 122MW vertical Francis machines in an underground machine hall.


MTL developed detailed refurbishment scope of works, and technical specifications for each of Manapouri’s 7 units. The specs were developed to identify and resolve individual machine defects and condition, as well as provide a common refurbishment specification, and performance requirements. Development of the scope of work required 2-3 weeks on site inspecting the machine, interviewing the stations operations and maintenance team, and reviewing maintenance records. This project presented a number of technical challenges, with the machine hall carved out of solid rock 100m underground.

MTL’s role included index efficiency testing of machines pre upgrade for baseline performance measurement. MTL has specific expertise in hydro machine efficiency testing, and the efficiency testing was performed in accordance with IEC 41:1991 and PTC 18.


Manapouri was undergoing an upgrade at the time of the refurbishment, with a second tailrace tunnel being built (a 10km long tailrace tunnel in parallel with the existing 40 year old tunnel). The reduction in tailrace level allowed the machine outputs to rise from 83MW per machine up to 122MW per machine. The client utilised MTL’s technical specifications as generic specifications for use throughout their hydro fleet.