Newfoundland and Labrador Hydro says a protection circuit failure at the Come By Chance terminal station is what caused the oil refinery to lose power last Monday.
“This type of thing is a big concern for us,” said Rob Henderson, manager of system operations and integration support for Hydro. “When we have an interruption to customers, we always dig into it and do a detailed analysis of the events, and particularly (for) something like the refinery, supply is so critical.”
Meanwhile, a spokeswoman for North Atlantic Refining said the company expects to have the Come By Chance refinery up and running again by the end of this week.
“We’re in the startup mode now. It can take probably until the end of this week, for sure, because it’s a very slow process of re-introducing all the product back to the unit. It’s something that has to be done very slow and carefully,” she said
The refinery typically produces home heating fuel, propane, and diesel, amongst other products.
The outage started at approximately 5 p.m. and power was restored by 9:20 p.m.
Heavy winds that day caused plastic debris to come in contact with high voltage equipment inside the station. Typically, this would only cause lights to flicker for a moment instead of a power outage, but not this time.
“Normally what would happen then is that we would isolate that particular piece of equipment and it would not result in a complete outage to the refinery — it just would have isolated (it) — because there’s a lot of components in there, and you have breakers to try to isolate that,” said Henderson.
“In this particular incident, when we did a close examination of everything that happened the next day, what we found was there was a component in one of our protection circuits that had failed, and that component was what caused the chain of events that caused the whole station to go out.”
Henderson said the failure was particularly surprising given the component in question bas been used at terminal stations across Newfoundland and Labrador for 20 years with no prior failures ever linked to it.
He said the circuits must be tested at least every five-to-six years. The one that failed at the Come By Chance station was tested in 2012. Since it was last tested, the circuit has been called into action several times without incident, excluding last Monday.
The component of the protection circuit has been replaced, and Hydro is now trying to determine why it failed.
“What we are doing, we have our engineers who look after the design of these circuits ... currently doing a review of the design to see if there is anything that we can do to prevent similar occurrences and perhaps revise the design, if that makes sense for the circumstance.”
He said that review is ongoing. How long it lasts will depend on the complexity of the solution. If it appears to be relatively simple, Hydro can react quickly, but if it is deemed to be more complex, Henderson said there may be a need for capital budget approval.
Henderson does not expect a failure of this type will affect other terminal stations given its rarity.
The last time Hydro can recall an outage affecting the Come By Chance terminal station was in October 1998.
The outage at the Come By Chance terminal station did not affect the Avalon Peninsula due to the presence of a transmission line that runs parallel to the two lines feeding into Come By Chance.