Widespread power cut leaves people in the dark

The Vientiane Electricity Department yesterday asked people and businesses to conserve electricity, following two major power cuts this week.

The department's Deputy Director, Mr Somphone Thammavongsay, said everyone must make a greater effort to use less electricity. He cited garment factories and irrigation pumps as especially large consumers of electricity in the wake of the power cuts.

The power cuts were the result of a grid overload, but occurred for two quite unrelated reasons on the nights of February 22 and 23, Mr Somphone said.

The outage affected not only a large area of the capital but three provinces using power generated by the Nam Ngum 1 dam - Vientiane , Luang Prabang and Xieng Khuang.

The 10-20 minute power outage on the evening of February 22 is believed to have been caused by generator failure at the Nam Ngum 1 dam.

Mr Somphone said one of the five generators was undergoing routine maintenance and was not generating power.

Maintenance procedures began in February and are set to be completed in August, he said.

But this alone was not sufficient to cause the sharp reduction in power supply. On February 22 at 18.50 pm two of the remaining four generators at the dam failed. Initial investigations found this may have been due to an automated system lock function that was activated, according to Mr Somphone.

The two generators were repaired in 20 minutes, restoring operation to four of the plant's five generators, sufficient to meet consumer demand.

Electricity department officials said an outage caused by a source supply issue on this scale had not occurred for 20 years. Most power cuts are localised and do not involve such fundamental failures in source supply.

In the second outage the following evening, on February 23 at 19.22 pm, the same three provinces and the capital were again left in the dark for almost 30 minutes. On this occasion a damaged electricity cable in Thailand 's Oudon Thani province was the cause.

Mr Somphone said the Lao grid partly relied on power from Thailand to sustain supply.

“When necessary we also use electricity from Thailand , but unfortunately the electrical cables in Oudon Thani province failed to deliver power on this occasion,” he said.

This was an unprecedented and unfortunate event, the department said. They have been assured by their Thai counterparts the damaged cable has been fixed.

The Lao electricity grid links to the Thai grid to stabilise power supply in both countries. When consumption in Vientiane exceeds supply capacity in Laos , electricity from Thailand is automatically diverted to Laos . Laos typically buys electricity from Thailand in the dry season and supplies electricity to Thailand in the wet season, when domestic demand declines.

Mr Somphone said power-hungry factories should cut production from 6 to 9 pm because demand for electricity by households was at its peak during these hours.
The extent to which demand contributed to the supply problems, the overload, and the widespread power outage is unclear.

By Souknilundon Southivongnorath
(Latest Update February 26, 2009)