▁month . ▁ ▁Power ▁T unn els ▁- ▁ 4 ▁t unn els . ▁ ▁L ength ▁about ▁ 8 5 0   ft ▁ ▁A verage ▁diameter ▁ 5 . 5 m , ▁steel ▁l ined ▁ ▁Power house ▁ ▁surface ▁power house ▁ ▁with ▁ 4 ▁pen stock s ▁to ▁power house ▁compr ising ▁ 4 ▁tur b ines ▁of ▁ 8 7 MW ▁each , ▁ 4 ▁air - co o led ▁gener ators ▁of ▁ 1 0 0 M VA ▁each ▁and ▁ 4 ▁transform ers ▁of ▁ 1 0 0 M VA ▁each . ▁ ▁Tur bine ▁type ▁is ▁vertical ▁Francis , ▁manufact ured ▁by ▁H IT AC HI ▁of ▁Japan . ▁Tur bine ▁sh aft ▁r ated ▁output ▁is ▁about ▁ 9 0 MW ▁at ▁r ated ▁gross ▁head ▁of ▁ 1 0 1 m . ▁ ▁Max imum ▁plant ▁dis charge ▁is ▁ 4 X 1 0 0 m 3 / s . ▁ ▁Plant ▁r ated ▁annual ▁energy ▁production ▁is ▁ 8 7 0 G Wh ▁based ▁on ▁annual ▁ra inf all ▁of ▁ 3 , 7 0 0 ▁million ▁cub ic ▁metres . ▁ ▁Tem eng gor ▁Dam ▁is ▁now ▁the ▁third ▁largest ▁dam ▁in ▁Malays ia . ▁It ▁was ▁once ▁the ▁largest ▁dam ▁and ▁largest ▁hydro elect ric ▁generation ▁facility ▁upon ▁completion ▁in ▁ 1 9 7 9 , ▁before ▁being ▁over t aken ▁by ▁the ▁Ken y ir ▁Dam ▁in ▁ 1 9 8 5 . ▁It ▁holds ▁a ▁special ▁place ▁in