CHAPTER V - POWER DIRECTIONAL DEVICES

Abstract

The power directional device is one of the basic parts of many contemporary types of protective gear for high-voltage networks; directional, distance, and H.T. directional. It is intended for the blocking of protection if a short-circuit occurs outside the limits of a given transmission line. An unequal power direction of the short-circuit at the two line terminals is a sign that the fault is outside the protected zone of the line. Taking into account that the short-circuit power is directed from the generator to the fault, it is concluded that at that end of the faulty line that is further from the fault, the short-circuit power is directed away from the bus-bars on the line side and at the opposite end nearer to the fault, the power is in the direction of the bus-bars. The power directional device consists of a directional relay/react to the sign of the power that depends on the positive of the short-circuit in relation to the point where the protective gear is installed.