Breaking New Ground: Digital Twin Helps Engineers Design Megawatt-Sized Circuit Breakers
November 18, 2015
We’ve all stood in the dark at least once after getting tripped up by power-hungry appliances. Typically, the remedy is just steps away: a quick flip of the circuit breaker switch, and you’re back in business.
It’s a simple fix, but it involves complex physics. “Circuit breakers protect our homes from electricity overload,” says Tim Ford, senior product manager for industrial circuit breakers at GE’s Industrial Solutions business. “This sounds easy, but the amount of energy they are often called on to dissipate is like grabbing the flywheel of a running car and stopping it.”
Ford should know. His team builds breakers that can disconnect a small power plant. Their latest device, called the GuardEon Molded Case Circuit Breaker, will be able to dissipate 2.7 megawatts. That’s enough horsepower to stop seven Porsche 911 Turbos cold in their tracks – if you could fit them inside a shoebox. The breaker is unusual since the team used powerful software for the first time to build a virtual prototype of the device – its “digital twin” – and tested it inside a computer.
Top image: After they ran the digital twin through tests inside the computer, they exposed a real-world GuardEon prototype to 100,000 amps at 480 volts. The breaker survived the short circuit. Image credit: GE Energy Management
It’s a numbers game taken to new extremes. The circuit breaker must withstand an electric arc – essentially a lightning-like discharge – that can reach temperatures as high as 19,500 degrees Celsius (28,600 Fahrenheit). That’s more than three times the temperature on the surface of the sun. In addition, the circuit breaker must withstand pressure of 17 to 20 atmospheres, the equivalent of diving 660 feet below the surface of the sea.
The breaker must also control the molten metal particulates created by the arc and handle electromagnetic forces reaching as much as 5 tons – the weight of an African elephant. All of this happens in less than a second in a volume smaller than the cavity of a microwave oven.
“When we design these devices, we can’t just pull out the circuit breaker design 101 book from college and look at formulas because the formulas don’t exist and that book is far from being written,” Ford says.
That’s why Ford’s business partnered with software engineers at GE Global Research Center and the University of Connecticut and designed GuardEon inside a computer. They’ve been using a customized version of the commercially available software ANSYS to build the “digital twin” that will enable them to study the effects of design changes with a level of detail that has been impossible to achieve through physical sampling and testing.
The team can use the model to simulate the electromagnetic, mechanical and fluid dynamic aspects of circuit breaker behavior and study their interplay. The preliminary use and adaptation of the “digital twin” also allows them to reach higher performance levels and move faster in bringing the device to the market.
“Multi-physics-simulation modelling helps us narrow down 10-15 different designs into three or four that we can use for physical testing and validation,” says Dhirendra Tiwari, principal engineer and technologist at GE’s Industrial Solutions business. “Without these capabilities, we’d have to send all of the samples to the lab for development and testing and then go from there. This is expensive and time consuming.”
This is not the first GE digital twin. The company is already using the approach to design more efficient wind turbines and even entire wind farms.
Ford says that “although the circuit breaker will launch without actual operating experience – and there’s no way around that – we have analyzed it hundreds of times in a virtual environment to find and eliminate inefficiencies and potential weak points that would not have revealed themselves during laboratory testing. That’s pretty cool.”