HomeNews Power Stations About Contact Language First Hydro Company Home > Power Stations > Dinorwig Power Station Dinorwig Power Station When it was fully commissioned in 1984, Dinorwig Power Station was regarded as one of the world's most imaginative engineering and environmental project. Today, Dinorwig's operational characteristics and dynamic response capability are still acknowledged the world over. Dinorwig is the largest scheme of its kind in Europe. Dinorwig is comprised of 16km of underground tunnels, deep below Elidir mountain. Its construction required 1 million tonnes of concrete, 200,000 tonnes of cement and 4,500 tonnes of steel. The station's six powerful generating units stand in Europe's largest man-made cavern. Adjacent to this lies the main inlet valve chamber housing the plant that regulates the flow of water through the turbines. Dinorwig's reversible pump/turbines are capable of reaching maximum generation in less than 16 seconds. Using off-peak electricity the six units are reversed as pumps to transport water from the lower reservoir, back to Marchlyn Mawr. DINORWIG FACTS & FIGURES Surge Pond Data: Dimensions of surge pond 80x40x14 metres deep Diameter of surge shaft 30 metres Depth of surge shaft 65 metres Generator/Motors: Type Vertical shaft, salient pole, air cooled Generator rating 330 MVA Motor rating 312 MVA Terminal voltage 18kV Excitation Thyristor rectifier Starting equipment Static variable frequency Generator-Motor Transformer: Number Six Approximate rating 340 MVA Voltage ratio 18 kV/420 kV Underground Caverns: Distance of power station inside mountain 750 metres Depth of turbine hall below top level of Llyn Peris 71 metres Machine Hall: Length 180 metres Width 23 metres Height 51 metres max Transformer Hall: Length 160 metres Width 23 metres Height 17 metres Diversion tunnel length 2,208 metres Width 6.5 metres Height 5.5 metres Maximum flow 60 cubic m/s Normal flow 1-8 cubic m/s Fall 1:1500 Pump/Turbines: Type Reversible Francis Number 6 Plant orientation Vertical spindle Average pump power input 275 MW Pumping period (full volume) 7 hours Synchronous speed 500 rpm Average full unit over all heads (declared capacity) 288 MW Generation potential at full load Output 5 hours Station power requirements when generating 12 MW Standby operational mode Synchronised and spinning-in-air emergency load pick-up rate from standby 0 to 1,320 MW in 12 seconds Transmission Switchgear: Type SF6 metal clad Breaking capacity 35,000 MVA Current rating 4,000 A Voltage 420 kV Excavations: Main underground excavation 1 million cubic metres (approx. 3 million tonnes) Total scheme excavations 12 million tonnes Contact Dinorwig Power Station Llanberis Caernarfon Gwynedd LL55 4TY 01286 870166 info@fhc.co.uk www.fhc.co.uk Ffestiniog Power Station Tan-y-Grisiau Blaenau Ffestiniog Gwynedd LL41 3TP 01766 830465 info@fhc.co.uk www.fhc.co.uk Manage Cookies engie.co.uk engie.com © FHC 2021 Cookies are used to make this website work and to enhance your experience. To learn more about the types of cookies this website uses, see our Cookie Policy. You can provide consent by clicking the "I Consent" button or by canceling this cookie notice. I ConsentManage Cookies Cookies are used to make this website work and to enhance your experience. To learn more about the types of cookies this website uses, see our Cookie Policy. We need your consent to use marketing cookies. Marketing cookies are used to track visitors across websites. Please select the checkbox below to indicate your consent. I consent I do not consent Save Preferences Your cookie preferences have been saved