Design of programmable AC voltage and current generators for testing energy meters

A prototype equipment that generates two AC sources of the same frequency for testing single phase energy meters is described. Their amplitudes, frequency and phase shift can be set through a keyboard pad. It consists of reference signal generators and amplifiers. The reference signal is generated using a microcontroller and two serial 16 bit digital to analog converters. The amplifiers use power transformers and feedback opamp circuits. The circuit can generate programmable 180-250 V,m, (1V/step) and 0.2-50 A(rms) (0.1A/step) sources with 0.1% full scale error and 2% harmonic distortion. Its frequency can be adjusted from 45-55 Hz (0.1 Hz/step) with 0.1% error. The phase is also adjustable from 0-360 degree with 1 degree/step.