The science behind the salty towers causing Nova Scotia power outages – Nova Scotia

When the electricity went out in the province earlier this month, Nova Scotia Power blamed a familiar foe.

The power company has been blaming salty towers for at least twelve years, but can the ice-melting mineral really turn out the lights?

Some people were skeptical. 

Nova Scotia Power says some winter outages come from a combination of salt and moisture:

  1. A cold winter wind blows salt onto its equipment over a period of hours or days.
  2. The temperature rises, adding moisture to the air. 
  3. That moist air causes arcing, which is when an electrical current discharges from transformers or wires as bright light or sparks and sounds like buzzing or crackling.
  4. The arcing causes a power outage.

CBC News phoned Mohamed El-Hawary, a professor of electrical engineering at Dalhousie University, to test the claim. 

“Our worst enemy is the salting of the roadways in the neighbourhood of the transmission towers,” he said. 

Routes near the briny sea greatly increase the problem. 

El-Hawary said if you look up at power lines, you’ll see the conductor lines, which are strung between towers, hanging from insulating cups. The cups are made of ceramic or composite materials.

Salting the path of least resistance

“It puts an insulation between the high voltage carried by the conductors and what we call ground, which is the metal structure of the towers,” he said. “The insulator cups have the job of confining the electricity.”

He said the layer of surrounding air also provides insulation, removing any path for the electricity to go from the lines to the ground. That lets us move electricity around the province without shocking anyone en route.

When salt — or any other contamination — gets in that air layer it opens a new “path of least resistance” for the lazy electricity to head to the ground. “This is a situation that is undesirable,” El-Hawary said.

Murray Douglas of EasternShoreMedia captured the dramatic results near Porters Lake on Jan. 4.

When that…

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