NATION-WIDE POWER FAILURE ON 5TH FEBRUARY, 1983

Mr S. Chandra Das asked the Minister for Trade and Industry (a) what cause or causes led to the major nation-wide power failure on Saturday, 5th February, 1983; and (b) what steps will be taken to prevent a similar occurrence in the future.

Dr Tony Tan Keng Yam: I would like to take advantage of this question to explain not only what caused the island-wide power failure on Saturday, 5th February, 1983, but also why it took many hours to restore full supply, and finally what we can do to minimize disruption and danger to life in the event of a power failure.

The power failure on 5th February, 1983, occurred as a result of a severe short circuit at a new section of the 230 kilovolt switchboard being installed and tested at Senoko Power Station Stage III which is under construction.

The short circuit was so severe that it created a surge of power equivalent to five times the power being generated to supply the entire Republic at that time. The extreme overload severely disturbed the electricity supply system and led to the tripping (automatic disconnection from the system) in rapid succession of the generators at Jurong, Senoko and Pasir Panjang Power Stations. All the power stations were affected because they are interlinked through the Republic's electricity supply network.

The power failure did not occur because of insufficient generating capacity. At present, the daily peak demand for electricity is about 1,350 MW but the total generating capacity of all the power stations is about 2,100 MW. There is therefore more than sufficient generating capacity to cater for Singapore's demand.

Let me now explain our electricity supply system and why it took several hours to restore full supply to the island. In a power station fuel is burned in the boilers which produce high pressure steam. This steam is used to drive the turbine-generators to generate electricity. Electricity generated at power stations is fed to four major 230 kilovolt substations through the 230 kilovolt cable transmission system. From there, electricity is distributed to consumers via some 3,600 substations and more than 33,000 km of their associated cable systems. This system of inter-linking power stations and substations through cables constitutes our electricity supply network.

Like all major electricity supply systems, Singapore's power stations are linked through the network. This has been found by practice to be the most efficient and economical mode of operation and affords flexibility and reliability. During a planned shutdown for overhaul and maintenance of equipment at one power station, electricity can be supplied from the other power stations. More important, if there is a fault in one power station causing a generator to trip, the other power stations with reserve capacity (or, in technical jargon, spinning reserve) will automatically take over the load thereby preventing power failure.

There is, however, an attendant disadvantage in such a system in that an extraordinary fault at one power station may affect the other power stations by virtue of the fact that they are linked. On 5th February, 1983, such an extraordinary fault occurred, causing such a severe overload that it tripped out all the generators in operation within seconds, nullifying the back-up system of spinning reserve.

When there is a total collapse of the electricity supply system, restoration of supply takes time because established safety procedures have to be followed. When the generators trip, the boilers go out and the fuel pipes to the boiler have to be shut down. The furnaces then have to be cleared of remnant oil vapour otherwise the boilers may explode on ignition.

Once the boilers have been started, it takes time to build up high pressure steam. The turbine-generators have to be run-up slowly and it takes about an hour before the generator can transmit any electricity into the system. There are technical and practical limitations to the speed at which the boilers and the turbine-generators can be loaded. This is a slow process because fast loading will damage the turbine-generators. The speed at which supplies are restored has also to be balanced with the rate of generation, otherwise the system might collapse again. That is why restoration of supply could only be started three hours after the system collapsed on 5th February, 1983.

This procedure of restarting the electricity supply system is universally followed by all utility authorities irrespective of the type of generator or boiler in use.

Can we prevent a recurrence of the particular fault that led to the island-wide power failure on 5th February, 1983? The answer is obviously yes. We can tighten up the precautions to be taken prior to carrying out testing of new high voltage equipment in the electricity supply system. This is being done by the PUB.

Can we ensure that we will never ever have an island-wide power failure? The answer, both theoretically and practically, is No - so long as our power stations are interlinked with automatic transfer of load from one station to another as the need arises.

Why, then, do we not change our system and instead have each power station service a separate, self-contained sub-network? The reason is because such a system has its own grave disadvantages. If a fault develops at one of the power stations, electricity would not be supplied automatically from another power station and the net result is that area blackouts would be more frequent and more prolonged.

In 1981 and 1982, there were 77 occasions when one or more generators in our three power stations tripped. However, because our power stations are linked in a network, the other generators were able to pick up the load and only on seven occasions were there power failures covering large parts of the Republic. In other words, the interlinking of the three power stations prevented 7O major power failures. This would not have been possible if the three power stations were not interlinked.

Furthermore, if the stations were not linked the generating capacity of each power station would have to be increased to even out the load if a particular generator in the power station was malfunctioning. This means higher costs and therefore higher electricity tariffs.

In a linked network system the generating capacity of the power stations are, in effect, pooled thus allowing economical operation since the more efficient generators can be used to supply a large percentage of the total load.

Taking all things into consideration the PUB, in common with all major electricity supply systems in the world, has decided that the linked network system is superior and, considering that the last island-wide power failure occurred 17 years ago in 1965, I think that the decision is correct.

Finally, what can we do to minimize disruption and danger to life in the event of power failures? First, we can and we have installed standby generators in essential service installations such as waterworks, gasworks, hospitals and the airports. These standby generators can be started up during power failures. Secondly, high-rise public and commercial buildings, shopping complexes and hotels are required, under the Building Control Regulations, to instal standby generators, which, during a power failure, will automatically be started up to bring all the lifts down to the first storey and open the doors. The standby generators also operate the fireman's lift, fire-fighting facilities and emergency lighting in the building. Thirdly, industries, commercial and other organizations which, because of the nature of their business, cannot tolerate power failures, should likewise instal standby generators. However, all standby systems must be properly maintained and serviced regularly so that they will work during emergencies.

With over 70% of our population living in HDB estates, we must clearly pay special attention to making sure that people are not trapped in lifts in HDB flats during power failures. I am happy to note that HDB has taken the lead to instal automatic rescue devices to bring lifts down to the nearest floor and open automatically in the event of a power failure. HDB has 5,559 lifts in their estates and they have installed these automatic rescue devices in about 5,400. The remaining 159 lifts are old and HDB intends to replace them. The management corporations of high-rise apartment buildings should follow HDB's example and install these devices for the safety of residents in the apartment buildings. Appendix I - DUTIES ON CIGARETTES AND TOBACCO (Cols. 441 - 442) Appendix II - DUTIES ON LIQUORS (Cols. 443 - 446) Appendix III - DUTIES ON PETROLEUM PRODUCTS (Cols. 445 - 446) Please refer to Hansard document. Please refer to Hansard document. Please refer to Hansard document. 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