Power measurement is important to obtain the corresponding energy costs for certain processes of production as energy is an essential cost factor. This master thesis compares different sensors and power measurement methods and implementations. After definition of power for sinusoidal signals as well as for signals with high harmonic content, a detailed analysis of different types of voltage and current sensors and correction methods is carried out. Linear loads and nonlinear loads caused by power electronics are covered. The second part of the thesis compares the application of analog multiplier circuits for power measurement with digital methods. The solution using analog multipliers is advantageous in case that also high frequency signal components due to power electronics are to be handled under low cost applications. Using a universal AD-converter box and digital programming of power calculations through virtual instruments based on extensive libraries of corresponding program files for data acquisition, calculation, and display provides a very flexible solution at high hardware cost and large programming effort.