Development of wide band AC measurement device with high accuracy

The working principle and design method of wide range and wide band alternate current measurement device are introduced in this paper. In this device, two-stage current transformer is used as a shunt to solve the problem of large current input, non-inverting composite amplifier technology is employed to improve the accuracy of amplified audio signal, the log and anti-log amplifiers are adopted to perform true rms conversion, and ultra-linearity A/D converter LTC2400 is used to implement digital sampling. Moreover, moving average filtering technology, frequency compensation technology and photoelectric isolation technology are used to improve the reliability and stability of measurement system readings. Experimental results demonstrate that the accuracy of measured frequency is in excess to 0.02% for the frequencies from 45 Hz to 65 Hz, and the linearity of measurement can reach 0.025% for the frequencies from 50 Hz to 10 kHz based on basic range of 2 A.