Purpose. To develop a concept for the implementation of a more advanced device designed for the busbar protection of power plants and substations which has advantages in technical operation over its traditional analogs by applying the phasedifferential principle of this protection. Methodology. When developing the concept of implementation of phasedifferential busbar protection, we used the method of comparative analysis, in particular, a qualitative analysis of the characteristics of busbar protection was carried out; difficulties encountered in the operation of traditional differential protection as well as advantages that can be obtained by introducing phase differential protection were considered in the work. Findings. Based on many years' experience in the operation of differential current protection at power system facilities, the problematic issues of its operation are identified. We suggest using the phasedifferential principle for busbar protection operation; its distinctive features are distinguished in comparison with traditional protections. The conditions for starting, tripping and re turning of the phasedifferential protection are determined, and there is suggested a method for determining the sensitivity of phase relay concerned to the angle. The phase characteristic of the protection is shown, which is the major operating characteristic which determines the width of the working zone and the blocking of this protection type. Originality. For the first time, use of phasedifferential busbar protection, the principle of which is based solely on comparing the phases of the secondary currents of bays, connected to the common busbar system, has been suggested. At the same time, there is no provision for the use of any additional protection relays, which can provide a protection starting and use a different principle of operation from the phasedifferential one. Practice value. The phasedifferential busbar protection relay can be accepted into the technical operation in the power system facilities as an alternative option of using the traditional differential current protection. It has a number of advantages and allows solving existing problems of protection operation caused by increased requirements for current transformers in differential busbar protection circuits, necessity of tedious calculations of its, рабочих уставок, information redunancy and complexity of modern digital relays, which perform the function of phasedifferential protection.

The article analyzes all disadvantages of differential busbar protection and known methods of possible realization of their phase-differential protection. The authors improved more advanced methods for comparing current phases by phase-differential busbar protection, in particular, logical operations for each proposed method are given, including verification conditions that are

Ключові слова: трансформатор струму, струмова похибка, кутова похибка, релейний захист, аварійний режим.