ISLAND-WIDE BLACKOUT (Action to prevent recurrence)

Mr Ivan Baptist asked the Prime Minister what caused the recent blackout that lasted for many hours resulting in trauma for the majority of the population, and what action is being taken to ensure that there will be no distress of this sort again.

Mr Lim Kim San (for the Prime Minister): Sir, I think Members of the House know that the electricity system in Singapore has grown tremendously in the last 10 years. Generating capacity of the system has grown from 464 MW (megawatts) in 1966 to 1.270 MW now. In the process of expansion the system has become more and more complex and sophisticated and certain automatic safety devices such as the in-built mechanism of "tripping" has to be introduced. "Tripping" means an automatic disconnection from the system in the event of a fault.

On the day in question a new generator of 120 MW capacity was commissioned at Senoko Power Station and it was feeding 30 MW of electricity into a circuit for distribution. At the same time, another generator generating 90 MW was sending electricity through the same circuit. This circuit was carrying 120 MW of power for distribution.

Just before 4.00 p.m, the burner of the boiler of the new generator failed and this generator tripped. This tripping automatically disconnected the transmission circuit and the other generator could not transmit power to the system. The sudden loss of 120 MW caused instability in the system which in turn triggered the tripping of the other generators at Jurong and Pasir Panjang `B' Power Stations. This resulted in an island-wide blackout.

With such a widespread blackout it takes time to restore the electricity to the system. But this can only be done progressively. Within half an hour after the blackout, electricity had been restored to the first areas and the situation had returned to normal within 6« hours. The blackout was so widespread because, for reasons of economy necessitated by the high fuel oil price, our spinning reserve was less than the capacity of the largest generating unit in operation. However, having had this experience now. the PUB will, in spite of the increased operating cost, be providing spinning reserve equal to the capacity of the largest generator in operation until the Senoko Stage I generators, i.e, the new 120 MW generators, are fully commissioned at the end of this year. By then, the teething problems encountered in commissioning a new power station will have been ironed out and we may revert to the more economical mode of operation, that is, having a spinning reserve less than the capacity of the largest generators in operation.

Mr P. Govindaswamy (Anson): Sir, can the Minister enlighten the House on this point? Four cables which were wrongly connected had burst because the engineers had not done their work properly. Have the engineers been working well or not?

Mr Lim Kim San: Sir, I am not aware that cables had burst as a result of wrong connection. As far as I know, 120 MW of electricity was transmitted through one circuit. 30 MW was generated by a new generator and, as with all things new, there are bound to be initial teething problems. The boiler of this generator developed a fault and this tripped off the generator. The automatic safety device which prevents users from being electrocuted and the system from being unduly damaged, then also tripped off the other generators. The blackout was not due to a wrong connection of cables.

Mr P. Govindaswamy: Sir, this blackout occurred on the eve of Deepavali. I would like to know whether this will happen again on Christmas eve?

Mr Lim Kim San: The timing was just accidental. Sir.

Mr Ivan Baptist: Sir, are there no standby generators to cater to this sort of problem?

Mr Lim Kim San: Sir, there are generators standing by. That is what is meant by spinning reserve. To illustrate, let me put it this way. You have a 10 horse-power car and you are travelling in it. To be sure of getting to the end of your journey you have another 10 horse-power car following you all the time. In case the car you are travelling in should develop engine trouble, you can then switch over to the reserve car and continue to your destination. Our largest generator at present has a capacity of 120 MW. To enable the system to continue providing electricity should our largest generator fail, there should be 120 MW generating capacity standing by. This standby is known as spinning reserve. However, because of the high cost of fuel we did not have that much spinning reserve. But now, having experienced it and knowing that there will be teething troubles with new generators and in spite of high costs, we are going to provide spinning reserve equal to the largest generator we have in service.