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Losses abound - The lowly secondary

Doug Houseman's picture
Visionary and innovator in the utility industry and grid modernization, Burns & McDonnell

I have a broad background in utilities and energy. I worked for Capgemini in the Energy Practice for more than 15 years. During that time I rose to the position of CTO of the 12,000 person...

  • Member since 2017
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  • Feb 25, 2022

The secondary is the conductor that runs from a service transformer to the meter at the service entrance for a premise.

The purpose of the secondary is to distribute electricity at its lowest voltage to the premise, since energy is a product of voltage times amperage, it also means the highest amperage.

When it comes to losses, it is not the voltage that causes them, but amperage. High amperage results in conductor heating, and hot conductors have higher impedance which causes more losses.

In a recent study of secondary conductors, the older the premise, the smaller the secondary conductor and the higher the losses. The smaller and longer the conductor, the higher the losses.

Now if we add electric vehicles, PV on the roof, and electrify heating, cooking and hot water in those premises, we raise the amperage on that secondary.

Not only do we raise the amperage, but we do it for longer each day, reducing the cooling time available.

So what?

In some premises, half of the current total system losses for that premise (transmission + distribution + secondary) are in the secondary. Half!

As we increase the demand for power (in either direction exporting or importing) those losses will increase further.

Is it time to address right sizing the secondary to reduce losses?

OBTW most European style system have longer secondaries, so this is not just a US problem. 

Matt Chester's picture
Matt Chester on Feb 25, 2022

So we hear a lot about the need for government spending for grid modernization-- does that include addressing issues like this one? Or is this not on the radar for federal dollars? 

Steve Wacker's picture
Steve Wacker on Mar 4, 2022

Matt - we're helping owners in Europe look at losses on the secondary, primarily due to deteriorating underground secondary.  Of course, they are far more concerned with economic losses due to the high price of electricity.  But there's more discussion of the carbon emissions of those lost kWh.

Doug Houseman's picture
Thank Doug for the Post!
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