For protection against electric shock in low voltage systems residual current devices are commonly used. However, their proper operation can be interfered when high frequency earth fault current occurs. Serious hazard of electrocution exists then. In order to detect such a current, it is necessary to modify parameters of residual current devices, especially the operating point of their current transformer. The authors proposed the modification in the structure of residual current devices. This modification improves sensitivity of residual current devices when high frequency earth fault current occurs. The test of the modified residual current device proved that the authors’ proposition is appropriate.
 HD 60364-4-41, Low-voltage electrical installations – Part 4-41: Protection for safety – Protection against electric shock (2007).
 Czapp S., The effect of earth fault current harmonics on tripping of residual current devices, Proceedings of the International School on Nonsinusoidal Currents and Compensation, IX Conference-Seminar ISNCC 2008, Lagow, Poland (2008), DOI: 10.1109/ISNCC.2008.4627489.
 Czapp S., Comparison of residual current devices tripping characteristics for selected residual current waveforms, Elektronika ir Elektrotechnika, vol. 100, no. 4, pp. 7-10 (2010).
 Czapp S., Borowski K., Immunity of residual current devices to the impulse leakage current in circuits with variable speed drives, Elektronika ir Elektrotechnika, vol. 19, no. 8, pp. 15-18 (2013), DOI: 10.5755/j01.eee.19.8.2883.
 Donahue, S.T., Storm C.L., Wetz Jr. D.A., Lee W.-J., Study of the effects of smart meter RF transmissions on GFCI outlets, IEEE Transactions on Electromagnetic Compatibility, vol. 56, no. 6, pp. 1361-1369 (2014), DOI: 10.1109/TEMC.2014.2354016.
 Freschi F., High-frequency behavior of residual current devices, IEEE Transactions on Power Delivery, vol. 27, no. 3, pp. 1629-1635 (2012), DOI: 10.1109/TPWRD.2012.2191423.
 Lee T.M., Chan T.W., The effects of harmonics on the operational characteristics of residual current circuit breakers, International Conference on Energy Management and Power Delivery, Proceedings of EMPD’95, pp. 715-719 (1995), DOI: 10.1109/EMPD.1995.500786.
 Luo X., Du Y., Wang X.H., Chen M.L., Tripping characteristics of residual current devices under nonsinusoidal currents, IEEE Transactions on Industry Applications, vol. 47, no. 3, pp. 1515-1521 (2011), DOI: 10.1109/TIA.2011.2125939.
 Roldan-Porta C., Escriva-Escriva G., Cárcel-Carrasco F.J., Roldan-Blay C., Nuisance tripping of residual current circuit breakers: A practical case, Electric Power Systems Research, vol. 106, pp. 180-187 (2014), DOI: 10.1016/j.epsr.2013.07.020.
 Schoneck J., Nebon Y., LV protection devices and variable speed drives, Cahier technique No. 204, Schneider Electric (2002).
 IEC/TR 60755, General requirements for residual current operated protective devices. 2nd edition (2008).
 Chwastek K., Szczygłowski J., The effect of anisotropy in the modified Jiles-Atherton model of static hysteresis, Archives of Electrical Engineering, vol. 60, no. 1, pp. 49-57 (2011), DOI: 10.2478/v10171-011-0005-8.
 Colin B., Kedous-Lebouc A., Chillet C., Mas P., Wound magnetic core consequences on false residual currents, COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 27, iss. 1, pp. 246-255 (2008), DOI: 10.1108/03321640810836807.
 Ladjimi A., Mékideche M., Babouri A., Thermal effects on magnetic hysteresis modelling, Archives of Electrical Engineering, vol. 61, no. 1, pp. 77-84 (2012), DOI: 10.2478/v10171-012-0007-1.
 Naghizadeh R.A., Vahidi B., Hosseinian S.H., Calculation of inrush current using adopted parameters of the hysteresis loop, COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 33, iss. 5, pp. 1794-1808 (2014), DOI: 10.1108/COMPEL-08-2012-0133.
 Nová I., Havlíček V., Zenek I., Dynamic hysteresis loops modeling by means of extended hyperbolic model, IEEE Transactions on Magnetics, vol. 49, no. 1, pp. 148-151 (2013), DOI: 10.1109/TMAG.2012.2218584.
 Czapp S., Elimination of the negative effect of earth fault current higher frequency on tripping of residual current devices, Elektronika ir Elektrotechnika, vol. 91, no. 3, pp. 85-88 (2009).