This paper was produced for the 2019 NAFEMS World Congress in Quebec Canada

Resource Abstract

The existing portfolio of medium and high voltage circuit breakers for control and protection of power trans-mission and distribution grids offers a wide range of topologies, covering broad market requirements from all over the world. Trends from future grid scenarios drive the need in research for mechanical spring- or electromechanical-actuated circuit breaker and switchgear solutions. The evaluation of functionality, safety and reliability lies within the scope of continuous development activities.



Using latest FE software solutions to develop realistic, three-dimensional transient structural mechanism simulation models of the high dynamic switching operations allows to reduce time and cost for prototype tests of function and lifetime. Also, possibilities for the development of digital twins are opened. As one main drawback of transient structural 3d FE simulations is the time requirement for modelling and simulation, different approaches for the reduction of simulation time are known and used. One possible approach is a combination of multi-body simulation as source of loads and finite element simulation for evaluation of stresses and life-time. Risks of this approach are discussed in this contribution.



The need for very realistic and detailed analysis of the switching operation is understood when looking at the extremely short switching times: about 50 ms are necessary in today’s circuit breaker products to either open or close circuits in medium or high voltage applications. In this short time, medium voltage applications need an energy of up to 400 J for performing the closing or opening operation. While closing, the energy from energy source (spring or electromagnet) is used to close the circuit breaker contacts and compress contact springs. While opening, the accumulated energy in the contact springs must be released and the contacts opened securely. To transfer such an amount of energy in short times, complex multi-stage transmission mechanisms are necessary. These transmission mechanisms consist of several stages. Many physical phenomena are present, e.g. nonlinear contacts, impact dynamics, friction, joint clearance or high speeds and accelerations. All this makes the circuit breakers highly stressed systems and it is essential to be able to predict and control their life-time and reliability already during early development stages.



Trends from future grid usage scenarios indicate the need for further reduction of switching times and allow only fractions of the current solutions. The differences in loads and stresses on the structural parts of a circuit breaker by the decreased switching times and the increased accelerations need to be considered for the development of future products. Besides the identification of general function of the new circuit breaker kinematics, the models and results are currently used to develop simulation methods for lifetime prediction, using methods from fatigue simulation.



The improved development process using dynamic simulation methods for mechanisms and drives enables decision-making on a larger virtual design basis, reducing development cost for prototyping. This helps ABB to ensure a strong market position also in the future.