Methods for the Construction of Protection with Magnetosensitive Elements for the Parallel Circuits with Single end Supply

The conventional transverse protection for the parallel circuits is considered. Its disadvantages and the methods for their elimination are discussed. It is noted, that the present protection has been proposed based on monitoring the currents ratio in the phases of the same name, and devoid of all the disadvantages of the conventional one, except for its use of current transformers with ferromagnetic cores. It is stated that the protections without current transformers construction problem is a fundamentally unresolved problem of relay protection. Three ways to solve it for parallel lines are proposed. The first and the second are to do it at the power supply side, the third one - at the receiving side. The first is to determine the damaged line by the time difference of reaching the set value by the currents in the same name phases, the line in which the current has reached the set value earlier is disconnected; the second is to control the angle between the differential current of the parallel lines and the current in each of the same name phases, the third is to control the time between the moments when the current in the line phase reaches the specified value. The circuits where these methods are implemented, are analyzed. With the help of mental modeling, their performance in various modes is confirmed.