Thunder theory in CLP voltage dip

The recent voltage dip in CLP's 400-kilovolt power supply system in Tuen Mun has been attributed by a veteran electrical engineer to the possibility of the CLP power station in Lung Kwu Tan being struck by thunder.

The incident, which occurred on Saturday afternoon, resulted in over 120 elevator incidents in Kowloon and New Territories, as well as about 40 reports of malfunctioning fire alarms.

In response to the incident, CLP said that a high-voltage facility in the Black Point power station malfunctioned around 1.29pm, coinciding with the hoisting of the thunderstorm warning.

It caused a momentary 0.1-second voltage dip, however, there was no interruption to the power supply during that time.

CLP's managing director, Joseph Law Ka-chun apologized for the incident, saying, "The sudden voltage dips inevitably occur in different power systems.

"We understand the potential impact [of the voltage dip] on the public, and our professional team has been focusing on offering technical support to our customers."

Ho Wing-yip, a veteran electrical and building services engineer, attributes the voltage dip to thunderstorms striking an outdoor facility at the Lung Kwu Tan power station. "While overhead power cable systems are equipped with thunder protection devices, their installation is not foolproof."

Ho suggested that CLP should enhance the protection of outdoor power-generating facilities by conducting more frequent inspections and maintenance of cables.

The incident occurred just one week after a temporary voltage dip in the 400kV overhead power line in Yuen Long, which was suspected to be caused by a wildfire in Shap Pat Heung.

The Environment and Ecology Bureau expressed deep concern regarding the series of voltage dip incidents in CLP's power system over the past months.

"The incidents caused elevators to malfunction and some people were trapped, and it was definitely not ideal," the bureau said.

"We understand the incident has raised public concerns about the safety of the CLP's power system and discontentment with the service quality."

It has requested that CLP provide an explanation to the public and implement effective measures for improvement.

The bureau also mentioned the public's desire to include the impact of voltage dips in the reward and penalty mechanism under CLP's Scheme of Control Agreement to enhance monitoring of the power supplier's services.

However, Kenneth Lau Ip-keung, an Executive Council member and chairman of Heung Yee Kuk, cautioned against relying solely on a penalty mechanism as a solution.

Lau acknowledged CLP's good reputation in maintaining a stable power supply. "Penalty may be a way out, but given that in the past, CLP has been maintaining a good reputation. The power station in Lung Kwu Tan has been there for over 40 years, and we have always been proud of the stable power supply."