The explosion opened a weak spot of the insulation, ultimately tripping all three feeders of the Kiya substation, he added.
The affected feeders were Kiya 1, 2 and 4 which serve the southern part of Saipan.
“Last night was a serious outage because it occurred on one of the two large (60-megavolt ampere each) substation transformers at Kiya,” Malae said.
CUC engineers and technicians on Tuesday checked the consequential damage and made the necessary tests and repairs, he added.
He told Variety he had to utilize personnel from the power plant because CUC didn’t have skilled personnel for the substation problem.
“ As serious as the damage was, it could have been much worse. The transformer could have suffered an internal short, which was what we were afraid of last night in the dark,” he said.
Malae said Transformers 2 and 1 back up each other in case of a situation such as what happened on Monday night.
However, he added, Transformer 2 had not been energized on “standby” at that time.
“Even though it was tempting to re-energize it shortly after the other [transformer] failed we agreed to delay this process until the transformer was thoroughly inspected,” he said.
They had to be extra careful not to damage the transformer which cost at least $1 million, he added.
In order to shorten the outage duration, Malae said they connected the Kiya feeders to Feeders 3 or 4.
After an inspection, he said they energized Transformer 2 and the Kiya feeders as well as Feeders 3 and 4 were returned to their normal configuration.
“The two short power interruptions late in the evening for some feeders was a result of this transfer,” he added.
The power distribution system, including the Kiya substation, is the vulnerable part of the power delivery system, he said.
This will continue for another two years at the present rate, he added.
However, according to Malae, power generation is now more stable and has more resources.
In January there were at least 10 hours of outages on account of the distribution system but zero hours due to power generation, he said.
