Harmonic Effects on Electromechanical Overcurrent Relays



The electromechanical overcurrent protection relays are designed to operate with sinusoidal current. The operation of protective relay with harmonic currents is not reliable. The literature on harmonics and relays covers mostly the theoretical studies. In this paper, the harmonic effects on operation of electromechanical inverse time overcurrent relay (ITOCR) were examined. Not common in existing studies, the behaviour of ITOCR was analysed with laboratory experiments for distorted waveforms. A type of induction disc relay was used as an electromechanical ITOCR in the experiments. The non-sinusoidal load currents that consist of different harmonic spectra were applied to ITOCR and these nonlinear-load currents were processed by a data acquisition card and a harmonic analysis programme in the computer environment. According to the experiment results, the pick up current and the operating time of the ITOCR increase proportionally to the total harmonic distortion (THD) value of the non-sinusoidal current. It is concluded that, this type of relay cannot protect the system reliably due to the harmonic components of current.

Anahtar Kelimeler

Electromechanical; Relay; Harmonic; Overcurrent

Tam Metin:

PDF (English)


İndekslendiği Kaynaklar


Listeleyen Diğer Kaynaklar ve Servisler



Creative Commons Lisansı
Doğuş Üniversitesi Dergisi'nin içeriği Creative Commons Atıf-Gayriticari 4.0 Uluslararası Lisansı ile lisanslanmıştır.


Doğuş Üniversitesi Dergisi
Acıbadem Zeamet Sokak, No: 21
34722 - Kadıköy, İSTANBUL
E-posta: journal@dogus.edu.tr