Abstract: A surge locating system and a method thereof which can accomplish the surge locating with high accuracy and with relatively simple structure. When the surge occurs, the voltage is generated on the neutral point of Y-connected three-phase alternating current transmission line because of losing a voltage balance on the three-phase alternating current transmission line. The surge locating can be accomplished by detecting the voltage generated in the neutral point. The neutral point is grounded, and the surge locating system according to the present invention is installed between the neutral point and the grounding point. The voltage generated in the neutral point is introduced into the surge locating system and the detecting time thereof is stored. This detecting time is stored in the respective stations, and the surge point can be located based on the detecting time difference between the stations.

Abstract: The invention relates to a system for detecting any defective point on a power transmission line by making use of highly-accurate time signal transmitted from a satellite and by utilizing a digital data processing system.

Abstract: A process for excavating and constructing a tunnel, and an excavating device are disclosed. This process is directed to excavating and constructing a tunnel under a railway or a road on a bank or on level land in the direction transverse to the railway or road. In this process, pits are dug on the opposite sides of the railway, and then an excavator digs into the wall of a pit on one side so as to go out of the wall of the other pit through the ground left therebetween. In this respect, a hollow casing unit of a box shape is coupled to the rear end of the excavator equipped with a screw conveyor. As the excavator advances or digs forward a given distance, another casing unit is in turn coupled to the rear end of the preceding casing unit, and then such a step is repeated, until the excavator goes out of the wall of another pit. In this manner, the excavator further digs into the wall of one pit in the position adjacent to the preceding run of casing units.