METHOD OF THROUGH CHARACTERISTIC LINEARISATION IN PULSE-TIME OHMMETRE OF RELAY PROTECTION Russian patent published in 2011 - IPC H01H83/16 H02H3/40 

FIELD: electricity.

SUBSTANCE: to produce a linear through characteristic between parametres of input resistance of power transmission line short circuit z_W.SC and duration Δt₁ of rectangular voltages pulses generated by comparator on the basis of periodical sequence of rectangular pulses with duration Δt1 and repetition rate 2f the second periodical sequence of rectangular voltage pulses is generated with constant amplitude, having duration Δt₂= 1/(2f)-Δt₁ and repetition rate f. From the second periodical sequence a harmonic is identified with frequency f, amplitude, acting and average values of which are linearly joined to the value of the module z_W.SC of short circuit resistance. At the same time the linearised through characteristic is the functional dependence, which linearly joins the value of the module z_SC of full resistance either with the amplitude or with the acting value or with the average value of identified harmonic of voltage with frequency f.

EFFECT: expansion of functional capabilities and increased accuracy.

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