FREQUENCY DIFFERENCE RELAY Russian patent published in 2004 - IPC

FIELD: electrical engineering; supply mains and generators operating under conditions of their signal amplitude instability. SUBSTANCE: relay has input signal frequency and amplitude meters, synchronized-signal frequency and amplitude meters, constant-factor multiplier, two comparators, two final elements, algebraic adder, inverter, dividing unit, multiplier, two adders, two subtracting units, two limiters, two low-pass filters; input and synchronized signal frequency meters function to convert input and synchronized signals in compliance with following mathematical expressions: U_o = A_o/f_o, U₁ = A₁/f₁, where U_o is signal at output of input signal frequency meter; U₁ is signal at output of synchronized signal frequency meter; f_o is input signal frequency; f₁ is synchronized signal frequency; A_o, A₁ are scale factors proportional to amplitudes of input and synchronized signals, respectively; input and synchronized signal meters function to convert input and synchronized signals into values proportional to their amplitudes and equal to scale factors A_o and A₁, respectively. EFFECT: enlarged functional capabilities and enhanced operating precision of relay. 1 cl, 2 dwg