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Niwa team measuring power line sag

NZ Newswire logoNZ Newswire 5/01/2017

Scientist Tony Bromley is travelling through New Zealand in January armed with party balloons and cardboard coffee cups.

The equipment will help him measure how far powerlines along the national grid might sag.

If the lines get too close to other objects, such as trees, outages and other issues could occur.

Mr Bromley, a Niwa atmospheric technician, says the lines expand with heat and the more power that goes down them the hotter they get.

"When that happens, the lines sag in the middle of the span between power pylons," he said.

"It's essential to know how low the sag could go to ensure the lines aren't going to touch anything."

Working out the potential depth of a sag involved calculations using temperature, wind, pressure, humidity and solar radiation measurements many metres off the ground.

Mr Bromley and his team are spending four weeks covering 1600km of lines from Southland to Auckland.

They are setting up temporary meteorological stations at ground level and filling party balloons with helium.

The balloons are attached to the coffee cups which contain transmitting sensors sending weather information back to the ground.

Once a pre-set height has been reached, an electric current is triggered and burns through the string, releasing the balloon. The coffee cup falls to the ground, gets retrieved and is used again.

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