Digital realization of frequency insensitive phase shifter for reactive Var-Hour meters

The paper describes a digital realization of a circuit for an additional phase shift of /spl pi//2 between two input signals, with a constant amplification nondependent on frequency. The circuit is intended for measuring the reactive power and energy of electric networks. The solution is based on a coupled digital integrator and differentiator and the microcontroller application. The results of simulation and experiments show that the solution is applicable in standard (classes 2 and 3) and precise reactive meters (class 0.2).