The test bench for simulation impact of core saturation on the current transformer on coordination of inverse relay protection

Departement of Electrical Engineering, Politeknik Negeri Bandung, Bandung, Indonesia

^* Corresponding author: supriyanto_suhono@polban.ac.id

Abstract

When the measurement-type Current Transformer (CT) is used for protection schemes, this condition causes problems related to the operation of the protection relay. This performance can provide the right output to be captured by the relay when using the CT type of protection system, and measurement CT will be appropriately used as a measurement instrument. When the primary current is greater, the denser the flux flowing in the iron core, and when a certain primary current value is reached, the iron core is unable to accommodate the flux that must be flowed. As a result, the value Es is unable to rise again, so the error ratio begins to rise, and the secondary current output is distorted. This research aims to design a tool that can display the distortion that occurs in the secondary current, and this research will evaluate its impact on the characteristics of the inverse-type overcurrent relay. The research method is R&D (Research & Development) by configuring a prototype analog test table so that saturation occurs on the CT connected to the protection relay. The results of the research Simulation of protection coordination failure due to core saturation can be shown, and the design of core saturation test equipment can be demonstrated. The root cause of core failure can be traced from the disconnection time deviation that occurs at the protection relay. The design of core saturation test equipment can be implemented to display protection failures due to core saturation and show the correlation between the voltage excitation curve and relay disconnection time. Testing CT ratio 30/5 with a burden of 1.5 VA, the operating limit is 183.3% of the primary rated rating, meaning that for CT with a primary rated current of 30 amperes, testing up to 60 amperes shows the results have not occurred core saturation.