ACCURATE REVENUE METERING WITH LOW POWER CURRENT AND VOLTAGE SENSORS ACCORDING TO THE RECENT IEC 61869-10 AND IEC 61869-11 STANDARDS

Abstract

In 2017 new IEC standards for low-power passive current transformers (LPCT) and low-power passive voltage transformers (LPVT) were established, the IEC 61869-10 and IEC 61869-11 respectively. The standard accuracy classes vary from 0.1 to 3.0. An accuracy class 0.2 or better in combination with a matching reading unit would make these new transformers suitable for revenue metering of commercial MV customers. Until recently, however, such an accurate LPVT was not available.This paper presents the latest development with the new QX sensor of 3M as an accurate LPVT, and an RTU of Netcontrol with modified I/O cards for reading out the LPVTs and LPCTs. Both low-power transformers comply to the new IEC 61869-10 and -11 standards. This paper shows that 3M’s LPVT is able to measure with an accuracy class of 0.2 during type testing. While the goal of this paper was to demonstrate class 0.2 accuracy in the field comparing the LPVT and LPCT combination with conventional metering using VT, CT and an industrial revenue meter, the measurement set-up made it difficult to proof and requires more in depth study.The implementation of this sensor technology will bring important benefits to network operators in that, the new LPVTs are significantly smaller than conventional VTs with much easier installation that does not require on-site calibration and which is suitable for retrofitting in any existing station. When this is coupled with the expected higher reliability and operational safety, the LPVT brings a new impetus to accurate revenue metering.