| Title |
Cause of the Unwanted Tripping of Type-A Circuit-Breaker Incorporating Residual Current Protection for Industrial Uses (CBR) |
| DOI |
http://doi.org/10.5207/JIEIE.2021.35.12.029 |
| Keywords |
Residual current; Temporary residual current; Type-A CBR; Unwanted tripping |
| Abstract |
The objective of this study is to identify the reason why unwanted type-A CBR tripping occurs at under 15㎃ which is the residual non-operating current of the CBR. All the nuisance trippings happened at around 13㎃ on an effective value with a few harmonic currents. Determining the cause, to begin with, the real residual operating currents of the tripped CBRs have been tested. Second, trends of the residual currents including temporary residual currents (TRC) and instantaneous residual currents (IRC) have been measured for twenty days. Then, the results have been compared with other non- tripping circuits. Lastly, the power qualities measured at the tripping circuit have been analyzed to ascertain some relationships between fluctuation of residual currents and power qualities. Upon conclusion of the study, it was assumed that the cause of inadvertent trippings was TRC added to permanent residual currents with a modest value over 13 ㎃ already present for several reasons. The measured maximum peak to peak value of TRC, which was simultaneous with the permanent residual current, was 279㎃. Last but not least, compared to other studies regarding the unwanted CBR tripping, there was little relationship between the fluctuation of residual currents and power qualities, at least in this study. |