Patent RU-2643680-C1 (RU)
Inventor: NIKITIN KONSTANTIN IVANOVICH
IPC: G01R31/00
Filed: 2017-03-27
Granted: 2018-02-05
Abstract: FIELD: electricity. 
     SUBSTANCE: method for identifying a steady-state alternating current in a conductor by means of a closing reed switch and a microprocessor, in which, in the laboratory, the first closing reed switch is placed in the inductor (CI) so that their longitudinal axes coincide, then alternating current is applied to the CI, gradually increasing it to current   , where   is the smallest current in the CI at which the reed switches (contact closure) occurs,   is the current amplitude, its value   is measured, the time   of the closed state of the reed contacts from the moment of action (short-circuiting) to the moment of reset (opening) of contacts at the first measurement and the current return   , wherein the reed switch is returned to its original position, further, the current is increased to I 2 >I 1 ,   is measured (  is the magnitude of the current amplitude for the second measurement) and time   from the moment of action to the reset at this measurement, then the current is increased to I 3 >I 2 ,   is measured (  is the magnitude of the current amplitude for the third measurement) and time   from the moment of action to reset, then the current is increased to I 4 >I 3  and so on, repeating previous operations before I n >I n-1 , where   , n-1 is number of necessary measurements of time and current   and   (i= 1, 2…n), N is current multiplicity in the IC with respect to the minimum current of the reed switch   , n=30÷40, N=50÷100, then the dependence of the current amplitude in the conductor on the time of the closed state   from the moment of operation of the first reed switch to its return   is constructed, and the obtained dependence is entered in the microprocessor (in (1), where   is the current amplitude in the conductor, C SF  is the current scale factor in IC at the current in the conductor, and h is the distance from the conductor to the contacts of the reed switch, ω K  is the number of turns in the first IC, l k  is the length of the first IC), then reed switch is at the design point close to the conductor and when it is triggered with microprocessor the time   of closed state of the reed switch is measured, and according to (1) dependence the amplitude of the   is determine, characterized in that at each i-m measurement   and   in the inductor is measured and also i-th actuating current   of reed, after all the measurements a dependency   (2) is built, the dependence (2) and   are introduced in the microprocessor, then in the laboratory in the second IC the second normally open reed switch is put so that their longitudinal axes coincide, then the AC voltage U (K2)  is supplied, the angle ψ between the supplied voltage U (K2)  and current   flowing in the second IC is determined, then gradually increasing U (K2)  to increase of current in IC to   where   is the smallest current flowing in IC, at which the actuation of the second reed switch (contact closure) occurs,   is the current amplitude, the value of the   time of   closed state of contacts of the second reed switch from the time of action to reset (contact opening) and the reset current   at which the reed switch returns to its original position are measured, then U (K2)  is increase to the increase of current in IC to     is measured, where   is the current amplitude, time   from moment of action to reset, and the actuating current   then U (K2)  is increased to the increase of the current in IC to     is measured, where   is the current amplitude, time   from moment of action to reset, and the actuating current   , then U (K2)  is increased to increase of current in IC to   and so on, repeating the previous operations to   , where   is the current in IC when the voltage applied U (K2) =120, k-1 is the number of required measuring of time and currents   ,   and   (i=1, 2…k), k=10÷15, further the dependence of the current   amplitude and of the actuating current operation in IC from time of closed state   from the moment of action of the reed switch to the moment of its reset   is built, and the dependencies are entered,   and ψ in the microprocessor, then the first reed switch is set in close proximity to the conductor, and the second IC with the second reed switch is connected to the terminals of the secondary winding of the voltage transformer, both of the reed switches can operate in parallel, therefore, the microprocessor can simultaneously perform the following operations, with the closure of the contacts of the first reed switch installed in close proximity to the conductor, astronomical time   and   is recorded, at short-circuiting and opening of its contacts occurred, respectively, then using a microprocessor the current in the conductor   is found from the dependence (2) after   , at which the reed switch has closed contacts, the time   and   is found from formulae   and    where   and   are the time intervals from the transition of the sinusoid through zero to triggering and from the moment of reset until the next transition through zero, respectively, then the astronomical time of transition of the current sinusoid through zero by the formula   is determined, at the actuation of the second reed switch with a microprocessor astronomical time   is recorded, the time   of closed state of the reed switch is measured, upon opening the second reed switch contacts in IC with a microprocessor astronomical time   is recorded and after dependencies (3) the current amplitude   and of the actuating current   values are determined, then the time   and   is found of formulae   and      where   and   are the time intervals from the transition of the sinusoid through zero to triggering and from the moment of reset until the next transition through zero, respectively, and the astronomical time of transition of the current sinusoid through zero in the second IC is determined by the formula   then the transition of a voltage sinusoid through zero is defined by the formula   this time is remembered until the determination of the next transition of voltage through zero, then using a microprocessor phase of steady-state AC current in the conductor is determined relative to the voltage according to the formula    
     EFFECT: expansion of the field of use due to the determination of the phase of the steady-state alternating current by fixing the astronomical time of action and reset moments of reed switches, determining the moments of transition of the current and the voltage sinusoid through zero used as the reference point. 
     2 dwg 
       КПР -  C SF   
       : 
     СР –  
     П – 
        :  
     К –  
     В –  
       :  
     М –  
     А –