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Engineers Use Simulation to Ensure Switchgears Can Turn Off High Voltage Power Lines

Switchgear from Lucy Electric

When engineers turn off a high voltage power line, it isn’t like switching off a lightbulb. At these high voltages and currents, the electricity can arc through the air. This arcing isn’t just dangerous for maintenance and emergency crews working on the line, it also puts stresses on electrical components.

Electrical switchgears are used to extinguish the arcs that can form during contact separations of high voltage lines. It splits the arc along a series of metal plates and smothers it with sulfur hexafluoride (SF6) gas. The switchgear also contains metal bars, or busbars, that distribute the current to a series of switching devices.

These switchgears must be designed to operate safely in both normal and extreme conditions — like lightning strikes. The challenge is that the current market demands that this equipment be compact. This tighter space means that the switchgear can experience higher electric fields and electrodynamic forces.

To address this challenge, Lucy Electric uses ANSYS Mechanical and ANSYS Parametric Design Language (APDL) to estimate the electrodynamic forces that a switchgear will experience under normal and extreme conditions. Its goal is to improve the performance of the switchgear by optimizing the shape, placement and durability of arc splitting plates.

Lucy Electric Uses a Variety of Simulations to Optimize its Electrical Switchgears

Simulations helped Lucy Electric’s engineers determine the forces acting on the arc before it reaches the plates and while the contacts are open.

The engineers used this simulation to test several plate geometries in a day. To achieve this speed, the simulation contained 2D and simple 3D models. This quick turnaround enabled the team to swiftly design plate geometries that could pull the arc where it could be extinguished.

Video shows the motion of an electric arc between the arc-splitter plates in a medium voltage SF6 insulated switchgear.

Other simulations that Lucy Electric’s engineers performed included:

  • Modeling the motion of the electric arc to determine the effects of splitter geometries
  • Simulating electric field strength distributions to predict pre-strike arcs
  • Calculating joule heating and temperature rises to reduce thermal loads
  • Calculating the mechanical stresses caused by resonance to determine how to limit them

To see how these simulations were done in ANSYS Mechanical and APDL, or how Lucy Electric’s engineers optimized the switchgear designs based on their results, read: Reducing Current Stress in Switchgear.