The Tribune

By JADE RUSSELL

Tribune Staff Reporter

jrussell@tribunemedia.net

AN electrical engineer says Bahamas Power and Light’s repeated blaming of lightning for power cuts does not hold up, arguing that poor maintenance and management of the grid are the biggest problems.

Quentin Knowles said lightning is a normal part of nature that any properly designed power system is built to withstand.

“But the frequency of it and the extent of it makes it cast doubt on the explanations that they provide,” he told The Tribune.

BPL has repeatedly cited lightning for major outages this year. In September, the utility said a lightning strike at the Blue Hills Power Station caused a widespread outage on New Providence, the second strike there in recent months. In July, after another lightning strike at the plant left communities without power for hours, BPL’s board ordered a post-incident review. Officials also blamed the summer heat for outages, but the outages have continued even as temperatures have cooled.

Mr Knowles, who stressed that he was making a general observation, said surge suppressors and lightning protection devices have been available for decades. If properly designed, installed and maintained, he said, they absorb most of the energy from a strike.

“Lightning occurs, and it occurs all the time,” he said.

He said a severe strike can occasionally cause a major disruption. But if every major lightning storm brings a power cut, it suggests the protection systems were not installed or designed properly, or have not been maintained.

He also questioned how a single fault at one station could black out the entire island. Using a hotel as an analogy, he said a faulty hair dryer in one room should trip only the breaker feeding that outlet, not shut down power to the whole tower.

“That should never happen,” he said of island-wide outages caused by a single fault, adding that they point to faulty design, protection schemes or maintenance.

Mr Knowles also rejected the argument that the country must tolerate outages because the grid is old. He said engineers at utilities in the United States had told him they operate equipment more than 50 years old that still works because it has been properly maintained.

“So I don’t really buy that argument that hey, we have this old, ancient, ageing system that needs to be replaced throughout,” he said.

He accepted that the grid needs modernising, but said much of the problem could have been avoided had proper maintenance practices been in place from the start. He estimated that more than 90 percent of the problems could be avoided with preventive maintenance, proper protection systems, adjustments when new load is added, and monitoring of major equipment.

He pointed to the 15MVA transformer that exploded at Blue Hills in July, causing an island-wide blackout. BPL said at the time that a suspected underground cable fault caused the explosion. Mr Knowles said he had no direct knowledge of the cause of that event, but that transformers of that kind are fitted with devices that monitor heat, load and the condition of their components, so that problems can be spotted well before a catastrophic failure. He said he was confident that a properly maintained transformer would not have failed that way.

He also suggested that some outages blamed on lightning may have other causes, such as rainwater seeping into cable trenches and reaching faulty cables, which then trips protective equipment. He said he had no evidence of this, and was speaking from experience in the industry.

Mr Knowles said utilities elsewhere investigate major failures thoroughly to find out what went wrong and correct it. He said he did not know whether that happens at BPL.

He said someone in an engineering WhatsApp group had shared a Tribune headline from close to 50 years ago reporting power cuts and grid instability at BPL’s predecessor, the Bahamas Electricity Corporation.

“I don’t think the full picture has been given to us,” he said.

Mr Knowles is an electrical engineer and electrical contractor who designs electrical distribution systems for homes, hotels and subdivisions. He said he does not work on utility-scale transmission and distribution, but knows enough about how those systems work to make an assessment.