City plans electrical improvements

Posted in: News
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Jan 24, 2013 - 8:49:31 AM

POWERING DOWNAs residents enjoyed a white Christmas in Marlow, city officials were facing the prospect of a dark holiday.
“It was touch-and-go for a while there,” said Todd Brady, the city’s electric superintendent. Our department “worked on shifts to make sure that didn’t happen.”
A persistent oil leak in the main transformer of Marlow’s electrical substation grew heavier in the cold snap around the holiday. If the oil level dropped to a certain point, the transformer could have locked up, sending the city into a chilly darkness.
The substation’s grim outlook has spurred the city council to move forward with plans to build a second substation and make significant repairs to the current one.
City administrator Janice Cain said “We are hopeful for the early part of 2015 to have the new substation built.” She added exact timing is not yet known.
In the meantime, repairs to keep the Marlow’s power flowing will mean outages from time to time, officials said. The same problem was the cause of a longer-than-expected outage in October.
The 138-kilovolt substation serves as the power hub for the entire city.
According to Brady, the station’s transformer is the heart of the system, and the leak exists in an aging component of that transformer.
“The transformer was manufactured in 1976,” Brady said. “And the load tap changer is a 1960’s design.”
The load tap changer (LTC) is the culprit of the leak but serves an important function.
“The LTC keeps voltage consistent to meet consumer usage, both high and low,” Brady said. “It’s similar to an accelerator in a vehicle when it’s on cruise control.”
Both the transformer and LTC, which is mounted on the side of the transformer, took significant damage during the ice storm of 2010. The storm also took down main transmission lines outside the city, knocking out power for nearly two weeks.
The transformer has also survived fires in 2004 and in the 1990’s.
During Christmas, the oil leak became so problematic, members of the Marlow Electric Department, with help from the City of Duncan, built a pump system to keep oil levels sufficient.
 “We started pumping oil on Dec. 21,” said Brady. “If the oil gets too low, the system will lock out to prevent further damage. Unfortunately, it will also take down the power for the entire city.”
Since late December, Brady has been chasing parts for the antiquated system. They have been hard to come by.
“I’ve talked to people across the United States looking for repair options,” Brady recalled. “Due to the age of the LTC, those options are few.”
Cain said the city has limited options and is looking into the prospects of leasing a new transformer, complete with a new LTC. But that will require a lot of work.
“The substation would have to be de-energized,” Brady pointed out.
Such an outage could take 24 hours or longer.
A mobile substation would limit that outage, but tracking down a mobile substation has proven difficult.
“(Mobile substations) just aren’t out there to lease,” Brady said. “And if one is found, you have to find someone who can hook it to our system.”
The city plans are to build a second substation adjacent to the existing one. By adding the second substation, and replacing the current transformer, Marlow would be able to divide the ever-growing electrical demand between two units – which would be less taxing on equipment.
“It also allows repairs to be made to one unit, while the other substation keeps power available to our residents,” Cain said.
There are still several steps before improvements can be implemented.
“The complexities of building a second substation include approvals at the federal level, as well as, area power sources,” Cain noted. “There is also the preparation of engineering, designing and building equipment.
“Our ultimate goal is to replace aging equipment, improve safety for employees, and upgrade load ability for growth,” Cain added.