Taipei, Aug. 15 (CNA) A sudden national power outage that occurred on Tuesday afternoon affected more than 6.68 million households in several counties in Taiwan, and the power supply was not fully restored until 9:40 p.m.

The resumption of power ended rotational power rationing measures implemented by Taiwan Power Co. (Taipower, 台電) in the affected cities and counties.

The power rationing program rotated in three areas in the affected counties: round A cut the supply to 2.37 million households, round B affected 1.95 million households and round C saw 2.36 million households having their power cut.

The power outage took place at 4:52 p.m., hitting the greater Taipei area, Taichung and Tainan, as well as Miaoli, Nantou and Chiayi counties due to an operational error at the Tatan power plant in Taoyuan.

An operational error that saw the plant's gas supply cut for two minutes by state-owned CPC Corp. (中油), Taiwan caused all of the six generators in the plant in Taoyuan's Guanyin District to trip, cutting the country's power supply by 4.35 million kilowatts --the full capacity of the power plant, which is the largest natural gas-fired power plant in Taiwan.

The reduced voltage caused by the six offline generators also affected the operations of a generator at a power plant in Taichung, leaving a total shortfall of 4.65 million kW nationwide, Taipower said.

To take responsibility for the power disruption, Minister of Economic Affairs Lee Chih-kung (李世光) tendered his verbal resignation, which was accepted by Premier Lin Chuan (林全).

Lee will deliver his formal letter of resignation on Wednesday or Thursday, Cabinet spokesman Hsu Kuo-yung (徐國勇) told the press, saying that the government is determined to locate the cause of the human error and hold all relevant people accountable.

Due to the blackout, several department stores and shopping malls in Taipei, Taoyuan and Taichung, such as Pacific SOGO Department Store, Shin-Kong Mitsukoshi Department Store and Far Eastern Department Store had to evacuate their customers soon after outage occurred. The Taipei 101 building also stepped up evacuation measures when the outage took place.

Located in the Taipei 101 tower, the Taiwan Stock exchange said that its computer system remained intact, since the exchange is equipped with an uninterruptible power supply and a back-up power system.

The power outage did not affect the operations of the Hsinchu Science Park, where many of Taiwan's top high-tech manufacturers are located, the park administration said in a statement, denying news reports of power disruptions there.

The country's unstable power supply has caused concerns about the high-tech sector's operations and even their future investment plans. The science park statement relieved many investors, as the industrial park houses many manufacturing giants, such as the world's largest contract chip maker Taiwan Semiconductor Manufacturing Co. (台積電).

Also unaffected by the outage, Taiwan's national defense system was running normally on the back of a back-up power system. Ministry of National Defense spokesman Maj. Gen. Chen Chung-chi (陳中吉) assured the public that the country's national defenses remained fully functional and able to deal with any and all adversaries.

The services of Chunghwa Telecom Co., one of the country's leading telecom operators was disrupted, while rival Taiwan Mobile Co. (台灣大哥大) said its base stations located in northern Taiwan had been affected the most. However, they said that due to their back-up power system, the disruptions were limited.

Far EasTone Telecommunications Co. (遠傳) said that its operations remained normal despite the blackout.

The government said that the public transportation system largely remained intact, with only some Taiwan Railways Administration stations affected, while the Taiwan High Speed Rail, airports and national highways suffered no impact from the power outage.

Before the power supply was fully restored, a total of 96 post offices islandwide were blacked out with their automated teller machines suspended, while the water supply in the greater Taipei area was also affected. (By Liao Yu-yang, Jeffrey Wu, Tien Yu-pin, Liu Chien-pang, Wang Shu-fen, Chiu Po-sheng and Frances Huang) 

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