D—4

Eighbank,— Although water for irrigation was drawn from the head-race continuously from 4th October onwards, an average of 21,689 units was generated per hour of running during the year. Excessive wind-blown rubbish in the headrace continues to cause trouble at the screens. The new mechanical screen-cleaner installation should make routine screencleaning less arduous, but the screens will still require regular and frequent attention to prevent excessive fouling because of the small screen area provided. Much maintenance work on the hydraulic equipment was brought about by the sand and silt in the water. Also, the necessity of draining the headrace through the machine when dewatering is required for the annual overhaul results in heavy silt deposits being left in the turbine and the tailrace. The station was shut down for annual overhaul from 22nd November to Bth December. The turbine runner, which showed considerable wear due to erosion by sand, was welded and ground. A weir was built in the tailrace by the Ministry of Works to reduce the water velocity and consequent erosion. Considerable erosion of the river-banks in the vicinity of the station took place, and protective work is being carried out by the Ministry of Works,

Machine-running Times

Arnold,— The river flow was sufficient to enable the station to operate continuously at or above full load except for a period between 17th and 24th September, when the output was reduced from 3,000 kW. to 2,800 kW.

Machine Running Times

Monowai.— The normal operation of the station was interrupted by ten faults due to surges on the line, two line faults one of which was accidentally caused during testing, and by a prearranged shutdown. The rainfall for the year was 57-38 in., an increase of 13-25 in. on last year. Floods occurred in November and March, and water ran to waste during these months.

20

Time on Load. Time Idle. Time Under Repair. Percentage Availability for Service. Generator No. . Hours. Percentage. Hours. Percentage. T^ N ° m Demand Demand (Hours). (Hours). 1 8,233 94-0 117 1-3 410 95-3

Time on Load. Time Idle. Time Under Repair. Percentage Availability for Service. Generator No. Hours. Percentage. Hours. Percentage. Not in Demand (Hours). In Demand (Hours). 1 . .. 2 7,686 8,386 87-7 95-7 566 50 6-5 0-6 508 324 94-2 96-3