METHOD OF CURRENT MEASUREMENT IN CONDUCTOR BY SEALED REED RELAYS Russian patent published in 2015 - IPC G01R19/00 

FIELD: measurement technology.

SUBSTANCE: method of current measurement in a conductor by sealed reed relays involves positioning of two sealed reed relays with NO contacts near conductor. The relays are adjusted so that they close contacts at trip currents I_TR1 and I_TR2 and open contacts at return currents I_R1 and I_R2. Time t₁ between sealed reed relay contact opening after tripping is measured, and measured current amplitude is determined by the formula: $$I_{m1}=\sqrt{I_{R1}^2+I_{R2}^2-2\cdot I_{R1}\cdot I_{R2}\cdot \cos \omega t_1^{}}/\sin \omega t_1^{},$$ where ω is angular current frequency. Then closed state time t₂ for the first sealed reed relay contacts is measured, and if the second sealed reed relay does not trip, current amplitude is determined by the formula: $$I_{m2}=\sqrt{I_{TR1}^2+I_{R1}^2-2\cdot I_{TR1}\cdot I_{R1}\cdot \cos \omega t_2^{}}/\sin \omega t_2^{}.$$ If both sealed reed relays trip, closed state time t₂ for the first sealed reed relay and time t₁ between sealed reed relay opening moments are measured, and current amplitude is determined as mean value of current amplitudes I_m1 and I_m2.

EFFECT: improved reliability.

2 dwg