POWER FAILURE ON 17TH JANUARY, 1978

Mr Ng Kah Ting asked the Minister for National Development and Communications what was the cause of the power failure on 17th January, 1978, and how long it took the authorities to restore the power supply.

The Minister for National Development and Communications (Mr Lim Kim San): Mr Speaker, Sir, at 9.34 a.m. on 17th January, 1978, a 120 megawatt generator at the Jurong Power Station developed vibration at one of its bearings, and its protective relays tripped it off the system. The resulting system instability caused another 120 megawatt generator, also at the Jurong Power Station, to trip out. The disconnection of these two generating units from the system activated the operation of system automatic under-frequency relays, cutting off power to Toa Payoh, Aljunied, Kallang Basin and Siglap areas. By 10.30 a.m. power had been restored to 50% of the affected areas, and by 11.34 a.m. the situation had returned to normal.

For the information of Members, under frequency relays are protective devices installed in the system to automatically disconnect loads in pre-selected steps when there is a certain loss of generating capacity in the system. The use of under-frequency relays which has only been recently introduced is to prevent a larger area from being affected and also to reduce outage time.