Base of the Jor Dam syphon bellmouth spillway and the up- stream end of the spillway tunnet. On the left embanking for Jor Dam is in progress
transformer hall, each excavated in good granite about 1,000 ft. vertically below the ground level. The exposed roof and sides of each cavern were rock-bolted with 1 in. diameter 10 ft. or 8 ft. long grouted rock bolts at 5 ft. centres, the whole surface covered in 3 in. x 3 in. x 10 s.w.g. mild steel mesh, and finally a layer of 2 in. minimum (4 in. average) thickness of 1:3 gunite (with 3 per cent Sigunite additive) was applied. Over 850 rock bolts were used in all. Permanent access to the power station is via a
62
View looking up Woh Power Station access tunnel, The 132 kV cables will be carried on the bench at the top of the left wall
2,400 ft. long tunnel with a down gradient of 1 in 7.
The machine hall is 200 ft. long by 70 ft. wide and is 96 ft. high from lowest foundation level. It houses three 50 MW generating sets, which can be remotely controlled from Jor power station control room. The three turbines are of single runner Francis type vertical shaft hydraulic waterwheels, each capable of develop ing 68,500 h.p. at 600 rev/min under a design head of 1,165 ft.
The three alternating current gen-
dropshaft.
Tidong The dropshaft itself is formed by 10ft. diameter concrete pipes and the air vent shaft by 2ft. 6in. diameter pipes. The space around the pipes is filled with concrete
erators, directly coupled to the water- wheels, generate at 11,000 V at a rat- ing of 50,000 kW at 0.9 power factor. The generators are cooled by means of a closed circuit air cooling system. the air being cooled by water pump- ed from the draft tube of each tur- bine.
The transformer hall is 120 ft. long by 50 ft. wide and 50 ft. high, and houses three forced-oil circulation, water cooled, type transformers which step up the voltage from 11,000 V to 132,000 V. Three-core 132,000 V oil-filled cables are run on a concrete bench on one side of the access tun- nel to connect each transformer to the surface 132,000 V switchyard, which is located near the access tunnel por- tal.
Control cables are run on a con- crete bench on the other side of the access tunnel.
Woh Switchyard
The 132,000 V switchyard has been designed as a double low level busbar switching station with provision for:-
3 machine circuits for the
Woh power station.
2 inter-connectors to Jor.
2 inter-connectors to Malim Nawar.
3 inter-connectors to Rawang.
1 bus coupler.
2-132/11 kV inter-bus transformer
circuit.
Single bus 11 kV switchgear will be used and the following circuits are included:-
1 transformer circuit.
3 machine circuits for the
Odak power station,
2 circuits for power station
auxiliaries.
Far East Architect & Builder September, 1966