Latest Trends in Non-Conventional Instrument Transformers Kesri Meena, Gulati Aruna, Kapil Vivek, Dey Ranajit, Chawla Puneet Bharat Heavy Electricals Limited (BHEL), India Online published on 6 February, 2020. Abstract With the continuous expansion and advancement of electrical power systems, the measured current and voltage values of the power system nodes require an increased protection/measurement accuracy, coupled with reduced complexity and maintenance requirements of the current/voltage measuring devices. Also, the conventional instrument transformers are unable to cater to some of the special power system applications like DC current measurement, ungrounded AC current measurement etc. In this paper, we will discuss various alternative techniques for current/voltage measurements using novel instrument transformers/transducers, with a special focus on Optical CT (OCT) and Zero Flux Current Transducers (ZFCT). This paper also highlights the advantages and disadvantages of optical current transformers compared to conventional current transformers, the impact/changes required on secondary system (Numerical Relays/Bay Controllers etc.) due to retrofitting of Optical CT in an existing/new conventional substation. With the modern day developments in Electronics and Optical Systems, most of the limitations of earlier days’ optical CTs have been addressed and the recent versions of Optical Current Transducers are becoming more and more suitable, reliable and economical for use in all types of power system applications. This paper also describes some of the developmental works going on for developing indigenous optical instrument transformers. Top Keywords Optical Instrument Transformer, Fibre Optics, Optical Instrument Sensor/Transducer, Zero Flux Current Transducer, Rogowski Coil, Process Bus. Top |