Development and research of Rogowski coil to operate under operating conditions of open switchgear

Abstract

The interest to use Rogowski coils (RC) as current sensors to design secondary systems increases due to application of microprocessor relay protection and automation devices, including those that support the reception and processing of information in a form of a digital code in the format of protocols defined in IEC61850, as well as the disadvantages of traditional electromagnetic current transformers. Despite the popularity of RC, there are many unstudied issues of their functioning under operating conditions of open switchgears of power facilities, especially when operating with modern relay protection and automation devices. The aim of the study is to analyze the effect of ambient temperature on the error of current conversion by Rogowski coils. Studies of Rogowski coils have been carried out using the experimental and industrial samples. During the research modern testing equipment has been used. The equipment is listed on the Unified Register of Measuring Equipment of the Russian Federation and has valid verification certificates. The analysis of the factors influencing the error of metrological channels has been carried out. The analysis is conducted based on traditional current transformers (CT). The factors influencing the measurement error of RC are systematized. Experimental data obtained as a result of the study of the RC conversion error in a wide temperature range are presented. It has been established that due to design solutions, it is possible to neutralize the influence of such factors as the position of the primary conductor, external electromagnetic fields, uneven winding, the number of layers of the secondary winding, and thermal expansion. The use of materials with a low coefficient of linear expansion to manufacture the core of the Rogowski coil makes it possible to obtain the metrological characteristics of the transducer that meet the requirements of normative technical documentation in a wide temperature range. Application of RC as a primary current sensor for relay protection and automation systems is a promising area that requires further comprehensive research, and specifically in the process of industrial operation.