As a result of the nastiest snowfall in five decades the Chinese
government has sent a working team to Chenzhou, the city worst hit
by snowstorms in south China's Hunan Province, to investigate
causes of the widespread power blackout.
The working team, organized by the National Development and
Reform Commission (NDRC), includes officials and experts from the
NDRC, the State Grid and power consultative companies. At damaged
transformer stations, they found that heavy and thick ice had
formed on power lines and poles, the cause of much of the
The minimum temperature in Chenzhou this winter was minus five
degrees Celsius. At first it seems odd that Chenzhou had such
problems, especially compared with northern China, where winter
temperatures can be as low as minus 20 to 30. Yet in the north
there is no ice formation on power supply lines.
"The humidity here is all to blame," said Liang Zhengping,
senior engineer with China Power Engineering Consulting Group
Corporation (CPECGC). "When the temperature ranges between zero and
minus five, the moisture in the air can easily freeze on power
lines and accrete gradually if bad weather lasts."
Wu Yun, chief engineer of CPECGC, said the iron tower supporting
the power lines usually weighs six tons, however, when ice becomes
thicker and thicker on it, it weighs some 50 tons or six times the
original, that's the reason it collapsed.
An official in charge of the investigation said that with
lessons learned from this snow and ice disaster, China will further
improve its emergency mechanism for power supply, with adjustment
to grid designs to raise their reliability.
The snow havoc over the past few weeks in China has resulted in
direct economic losses of about 80 billion yuan (11 billion U.S.
dollars), toppled 300,000 homes, damaged 90 million hectares of
crops in 19 provinces and regions, the Red Cross Society of China
said earlier this week.
It has also killed scores of people and disrupted transport and
power services across a large swathe of the country's southern,
central and eastern regions.
(Xinhua News Agency February 9, 2008)