METHOD TO FORM ELECTRICAL VALUES BROUGHT TO MATCHING CIRCUIT IN ONE-SYSTEM DEVICE TO IDENTIFY MODULE CHANGE BETWEEN PHASE VOLTAGES IN THREE-PHASE AC SYSTEM Russian patent published in 2010 - IPC H02H3/26 H01H83/14 

FIELD: electricity.

SUBSTANCE: device contains matching circuit having two inputs and one output. Besides each of the inputs is supplied with the first and second single-polar electrical d.c. voltages. Output voltage is created at output, which is functionally coupled with difference between the first and second electrical values or with the result of their division. The first electrical value is formed depending on the required sensitivity. In addition, the second electrical value is functionally coupled with the module of the corresponding symmetrical inter-phase voltage, which is taken as design value. For example, to achieve maximum sensitivity to the change of inter-phase voltages, the first electrical value of direct current is formed based on multiplication of four co-factors. The first of them is defined by the half-sum of three inter-phase voltage modules. The other three are defined by the difference of modules half-sum and corresponding module of inter-phase voltage. Besides the second electrical value which is compared with the first one, is numerically set by multiplying factor 0.1875 and raised to a forth positive power by design module of inter-phase voltage.

EFFECT: increased sensitivity.

7 dwg