Study of an accurate electronic power measurement technique using modified current transformer and potential transformer

Abstract

In high tension power measurement, potential transformer (PT) and current transformer (CT) are used in order to reduce high tension voltage and current, respectively. But both PT and CT suffer from ratio error and phase angle error, which may produce severe error in power measurement. In the present paper, modified designs of PT and CT are combined to develop an electronic power measurement circuit in order to reduce the measurement errors. The modified PT and CT have reduced phase angle error and ratio error. In the power measurement circuit, the instantaneous product of the outputs of these PT and CT is determined by using a simple light emitting diode (LED)-light dependent register (LDR) or LED-LDR-based product circuit. The operation of the proto type power measurement unit designed in the present work has been experimentally tested and the measured outputs are compared with the readings of laboratory standard wattmeter. The experimental results are reported in the paper. Very good linear characteristics are observed.

A Development of a Capacitive Voltage Divider for High Voltage Measurement as Part of a Combined Current and Voltage Sensor

“…Accuracy after mathematical correction is also within limits of most common classes of inductive voltage instrument transformer [3].…”

“…For example, for voltage instrument transformers up to 24 kV, it is 50 kV Root Mean Square (RMS) for 60 seconds and voltage pulse 125 kV 1.2 μs/50 μs [2]. However, their disadvantages are high cost and weight [3] and increased measurement error for non-sinusoidal waveforms or transients [4].…”