Advanced circuit breaker technology engineered for power reliability and uptime

ABB developed the VD4-AF circuit breaker specifically to provide a high-quality, reliable solution for electric arc furnaces. It can provide up to 150,000 mechanical operations, including switching the furnace on and off, without refurbishment, and offers rapid replacement with a roll-in and roll-out solution when overhaul is required.

InfraBuild recycles scrap metal to produce steel “long products” such as reinforcing bar, merchant bar and rod for mesh. Aguilar describes the electricity-powered arc furnace as being “like a giant welder that creates a lot of heat and melts the steel”. With this sustainable process—the circular economy in steel, and the potential to be powered entirely by renewable energy, compared to coal-fired and catalyzed steel production—it supplies a variety of industries, from civil and commercial construction to residential and rural sectors.

At InfraBuild’s Laverton “melt shop”, scrap metals are loaded into the furnace for melting, and molten steel is poured into a ladle which moves it on for further processing. “The full cycle takes 40 minutes,” explained Aguilar. “On either side of melting, power to the furnace has to be stopped.” The melt shop operates 24/6, allowing one day for what he calls “housekeeping.” Continuous, dependable operation of the circuit breaker, a sophisticated, designed-for-safety, remotely operated device is essential.

Aguilar and his project team are responsible for capital projects at InfraBuild’s Laverton plant. In recent years these have included upgrades of the medium-voltage transformers supplying the melt shop and powering of a new electric arc furnace.

The circuit breaker was the final component of electrical infrastructure to be upgraded. Having carried out a significant number of operations, its risk of unreliability was growing and its age meant it became increasingly difficult to repair as spare parts were no longer available. “We got to the point where even our spare just couldn’t be replaced if it showed signs of approaching failure,” said Aguilar.