Studies On Ac Voltage Measurement By Sampling Method

Digital sampling measuring system was developed at NIM. AC signals under test were transmitted into the input of AD converter by voltage follower. Under the control of MCU square AD converter synchronously sampled the signal by full period, and the sampling data was transmitted by photo-coupler and calculated by computer. The sampling results compared with the measurement results of FLUKE 5790A. The agreements were within 2x 10(-5). It was found that the dominating part of the uncertainty in the system is the Integral Nonlinearity (INL) of AD converter, and the influence of quantization error can be decreased by increasing the sampling frequency.