• DRAGOS-STEFAN NICOLESCU ICPE, Department of Electrical Apparatus, Bucharest, Romania Author
  • ALEXANDRU RADULIAN ICPE, Department of Electrical Apparatus, Bucharest, Romania Author
  • MIHAI MARICARU University POLITEHNICA of Bucharest, Department of Electrical Engineering, Bucharest, Romania Author
  • SEBASTIAN PRICA University POLITEHNICA of Bucharest, Faculty of Electrical Engineering, Bucharest, Romania Author


Linear direct current actuator, Nd-Fe-B permanent magnets, High force, High holding force, High air gap, Ferromagnetic circuit, Numerical analysis, Specially designed coils


This paper presents the design, simulation, and experimental validation of a direct current linear actuator. The proposed actuator is similar in design to an electromagnet, but it uses Nd-Fe-B permanent magnets for producing a high holding force when it is in the closed position. From this point of view, the main purpose of this paper is to analyze the working principle of the actuator and to explain the advantages obtained by using a special geometry of the magnetic circuit. Such a linear actuator can be used in electrical equipment, like high voltage vacuum circuit breakers. The proposed linear actuator ensures high force during the closing, which is produced by a coil specially designed for this maneuver, and also a high force when the air gap is minimum, produced by Nd-Fe-B permanent magnets. The magnetic problem was solved using FEMM package, which has a specially designed LUA script incorporated in it. Mechanical parameters were determined with MATLAB program, by implementing numerical integration.


(1) P.G. Slade, The Vacuum Interrupter – Theory, Design and Aplication, CRC Press, NewYork, 2001, pp. 423–430.

(2) A. Radulian, N. Mocioi, Numerical Modelling of an Electromagnetic Actuator for Vacuum Contactors, International Conference and Exposition on Electrical and Power Engineering – EPE 2014, Iasi, 16-18 Oct. 2014, pp. 204 – 209, Publisher: IEEE, Romania.

(3) A. Timotin, V. Hortopan, A. Ifrim, M. Preda, Lessons of Basics Electrical Engineering (published in Romanian), Editura Didactică și Pedagogică, Bucharest, 1970, pp. 207-345.

(4) A. Radulian, Electromagnet in hybrid construction with excitation coil and permanent magnet, Patent No. RO 129746 / 29.11.2019.

(5) G. Dumitrescu, G. Tuluca, V. Neacsu, M. Badic, Integrated electromagnetic device for actuating electric vacuum switching apparatus, Patent No. RO 120302 B1/18.12.2003.

(6) M. A. Costea, G. M. Vasilescu, Direct calculation of the operating time of a DC electromagnet (published in Romanian), Revista Electrotehnică, Electronică, Automatică (EEA), 59, 4, pp. 37–42, 2011.

(7) A. Radulian, Modeling of an electromagnetic device with permanent magnets using the finite element method (published in Romanian), Revista Electrotehnică, Electronică, Automatică (EEA), 60, 1, 2012.

(8) M. A. Costea, G. M. Vasilescu, Operating Time of an Electromagnet with Nonlinear Ferromagnetic Armatures (published in Romanian), Revista Electrotehnică, Electronică, Automatică (EEA), 59, 3, pp. 62–67, 2011.

(9) S. Nitu, C. Nitu, G. Tuluca, G. Dumitrescu, Dynamic behavior of a vacuum circuit breaker mechanism, IEEE 23th International Symposium on Discharges and Electrical Insulation in Vacuum, 1, pp. 181-184, 2008.

(10) A. Radulian, M. Maricaru, I.V. Nemoianu, R. Creţu, New solution of linear dc actuator with additional permanent magnets: working principle, design and testing, Rev. Roum. Sci. Techn.– Électrotechn. et Énerg., 1, 2017, pp. 3-7.

(11) Y. Yoo, D.K. Kim, B. Kwon, Optimal design of a permanent magnetic actuator for vacuum circuit breaker using FEM, Journal of Electrical Engineering & Technology, 1, 1, pp. 92~97, 2006.

(12) D. Meeker, Finite Element Method Magnetics - Version 3.1 – FEMM 4.2 Manual, 2002.

(13) B. Herscovici, M. Preda, D. Ionescu, C. Dascalu, D. Catrina, A. Copolovici, High Voltage Electric Apparatus (published in Romanian), Ed. Tehnică, Bucharest, 1978.

(14) P.G. Slade, Vacuum interrupter design and application – A Lecture Series, Westinghouse & Cutler-Hammer Products.

(15) E. Nicolau, Introduction on modern theoretical electromagnetism (published in Romanian), Ed. Academiei Republicii Socialiste Romania, Bucharest, 1974.

(16) A.M. Chaly, O. I. Chervinskyi, V. N. Poluyanov, New generation of vacuum circuit breakers with monostable magnetic actuator, 18th Int.l Conference on Electricity Distribution, Turin, 6-9 June 2005.



— Updated on 09.01.2022




Électrotechnique et électroénergétique | Electrical and Power Engineering

How to Cite

HIGH FORCE HEAVY DUTY DIRECT CURRENT ACTUATOR. (2022). REVUE ROUMAINE DES SCIENCES TECHNIQUES — SÉRIE ÉLECTROTECHNIQUE ET ÉNERGÉTIQUE, 66(3), 139-143. https://journal.iem.pub.ro/rrst-ee/article/view/29 (Original work published 2021)