METHOD FOR MEASURING FAULT CURRENT Russian patent published in 2015 - IPC G01R19/30 

FIELD: electricity.

SUBSTANCE: method for measuring fault current in conductor by means of reed relays lies in that n reed relays with normally open contacts are installed closed to the conductor and aligned so that they close contacts at pick-up current of I_P1 and I_P2 and open contacts at drop-off current I_D1 and I_D2. At that n reed relays are mounted at safe distance h₁ h₂, …, h_n-1, h_n form the conductor. The reed relays are set so that they operate at pick-up current I_Pn>I_Pn-1>…>I_P2>I_P1 and return to initial position at drop-off current I_Dn>I_Dn-1>…>I_D2>I_D1. Then time is measured between closure of the first and second reed relay, …, n-1^th and n^th reed relay, time between operation and return of n^th relay, time between return of contacts of n^th reed relay and return of contacts of n-1^th relay, …, return of contacts of the second reed relay and return of contacts of the first reed relay. With the obtained data target current curve I=f(t) is plotted, approximated as I(t)=A₀+A₁·t+A₂·t²+A₃·t³+A₄·t⁴+A₅·t⁵+A₆·t⁶, where A₀, A₁, A₂, A₃, A₄, A₅ and A₆ are polynomial coefficients, and maximum current deviation is defined as amplitude of the measured fault current.

EFFECT: fault current measurement accuracy improvement.

2 dwg