D—4

in the vibration present since the steel runner was fitted in 1939. Incidental repairs ■or routine maintenance only were required on each of the other machines —viz., Nos. 4, 5, 6, and 9. A severe earthquake shock, thought to originate in the Birdwood Range, ■occurred at 00.35 hours on 27th June. Dafnage resulted at the lake outlet dam, where the concrete wing walls were cracked, and at the station, where some six dozen window-panes were broken, and all but three of the brick chimneys of cottages had to be dismantled and rebuilt. Repair work was completed in September.

Machine-running Times

Waitaki.—The highest daily river flow was 34,522 cusecs on 19th October, and the minimum weekly average flow was 3,641 cusecs on 14th July. The average flow for the year was 10,942 cusecs, as compared with 15,157 cusecs during the year ended 31st March, 1946. The average daily" flow for the week ending 31st March was 8,800 cusecs, as compared with 10,840 cusecs the previous year. The rainfall recorded for the year ending 31st March was 19-71 in. Cavitated areas in turbine runners and runner skirts were welded up and ground to shape. Circulating-pumps were put in the thrust-bearing lubricating-oil systems of Nos. 3 and 4 units. Two gate-arms and three breaking-links, broken on No. 4 due to an obstruction, were replaced from spares. Apart from resweating of No. 2 main exciter commutator risers, the generators gave excellent service and required only routine maintenance.

Machine-running Times

Highbank.—During this, its second, year of operation the station was run intermittently in March, 1946, and then practically continuously until 25th November, when it was shut down until Ist April, 1947, to allow the Public Works Department to clean out the head-race. The station's continuous running-capacity was a valuable contribution to system requirements.

22

Generator No. Time on Load. Time Idle. Time under Repair. Percentage Availability for Service. Hours. Percentage. Hours. Percentage. Not in Demand (Hours). In Demand (Hours). 1 5,280 60-3 2,069 23-6 1,400 11 83-9 2 6,297 71-9 2,046 23-4 417 95-3 3 5,904 67-4 2,520 28-8 336 96-2 4 2,390 27-3 6,320 721 50 99-4 5 2,349 26-8 6,389 72-9 22 99-7 6 2,136 24-4 6,256 71-4 368 95-8 7 2,235 25-5 5,297 60-5 1,228 86-0 8 3,160 36-1 4,069 46-5 1,531 82-6 9 3,822 43-6 4,935 56-3 3 99-9

Generator No. Time on Load. Time Idle. Time under Repair. Percentage Availability for Service. Hours. Percentage. Hours. Percentage. Not in Demand (Hours). In demand (Hours). 1 7,745 88-4 993 11-3 22 99-7 2 7,467 85-2 1,209 13-8 84 99-0 3 5,485 62-6 3,037 34-7 238 97-3 4 4,963 56-6 3,031 34-6 766 91-2