A look back in time at an innovation in distribution

Nicholas J. Conrad and Edmund O. Schweitzer

As today’s energy distribution system is rapidly changing making its operations more reliable and safe, but in other ways more challenging, it’s worth remembering how far technology and operations have come. ES&D editor Nichola Davies asked S&C Electric Company, which has been around for 100 years, to take us back in time.

When Australia’s electricity distribution system was first built in the 1890s, it primarily consisted of linking buildings for the purpose of sharing electricity.

Original factory at 4435 N. Ravenswood Ave.

Tamworth in NSW, with a population of about 3000 at the time, was the first place in Australia to supply electricity to the public at large, switching on arc and incandescent street lighting on November 9, 1888.

The early 1900s led to the development of utilities as we know them today, and a wider expansion of distribution systems and generation capacities. According to S&C’s vice president of the Asia Pacific business unit Jason Lander, this expansion provided the opportunity for electric connections at more homes than ever before, and required a swift development for equipment and solutions to meet increased demand.

Cutout line in 1954

The 1900s also gave way to the construction of many distribution substations to house electrical equipment and further extend the reach of the grid.

“While revolutionary at the time, most of the switching and protection technology used in the early 1900s were unreliable and tended to operate unnecessarily,” Mr Lander said.

Some early fuses were mounted on stone bases for durability and additional insulation.

“Unreliable switching and protection technology often led to large fires, which posed a significant financial and reputational risk for utilities.”

In the early 1900s, distribution substations were primarily housed indoors to protect equipment from weather and exposure. The switching and protection equipment used to protect these indoor substations posed significant fire risks, even when operated correctly. Plus, a design flaw in early power fuses made them an unreliable protection option.

Jason Lander explains, “Developed in 1890 as a protection device for other assets in the electric system, a power fuse was designed to break the flow of current.

“When a power fuse was exposed to a short circuit, resulting in increased current, the power fuse operated. This resulted in the thin wire element housed in the power fuse to melt and split in two.

“The separation of the element was designed to prevent the flow of current to the rest of the system, protecting upstream equipment. However, even when a power fuse operated correctly, there was still a high likelihood of arcing between the two ends of the element given their proximity.

“In addition to arc-prone power fuses, distribution substations also utilised, highly flammable, oil-filled switches.

“The combination of these two switching and protection solutions when a power fuse arced could produce intense fires capable of destroying substations.”

This led to development of the liquid power fuse in 1909 by Edmond Schweitzer and Nicholas Conrad in 1909, following the investigation of a distribution substation fire caused by a power fuse.

“The liquid power fuse is a spring-loaded fuse, housed inside a glass tube, filled will a fire-suppressing liquid,” Mr Lander explains.

“The fusible element used in the liquid power fuse had a higher melting point than alternative power fuse options at the time, resulting in greater precision and fewer unnecessary operations.

“This device provided the first reliable and economical means for protecting equipment in distribution substations from short circuits.”

In 1911, Edmond Schweitzer and Nicholas Conrad formed Schweitzer and Conrad Inc, today known as S&C Electric Company. The two early pioneers in the field set the tone for a century of innovation in the distribution sector, and counting.

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