Multipoint ground

Abstract: The invention discloses a PT secondary circuit online N-line multipoint ground fault detection method and device. The method comprises the following steps: both of the jaw of a first split core type current transformer (CT1) and the jaw of a second split core type current transformer (CT2) are installed on a common circuit N600(an) of the PT secondary circuit, wherein the secondary winding of the first split core type current transformer is serially connected with an adjustable resistor (Rw); the resistance of the adjustable resistor (Rw) is adjusted so as to be changed according to a preset time-resistance curve, and a first time-current curve of the secondary winding induced current of the second split core type current transformer is recorded synchronously; the first time-current curve is compared with the preset time-resistance curve, if the change modes of the two curves tend to be the same, then an N-line multipoint ground fault is judged to exist in the PT secondary circuit, or else, no N-line multipoint ground fault is judged to exist in the PT secondary circuit. According to the invention, advantages of safety, reliability and high efficiency can be realized.

Abstract: The authors expect to establish a series of methods to simulate the non-stationary spatial correlative time histories of multi-point ground motion.An improved simulating method is presented.By modifying the random phase angle,the authors solved the problem in which the time histories of ground motion were not similar when the points were adjacent.Two simulating methods were put forward for the case when the empirical law of phase difference spectrum was known or not.A new method to simulate the time histories of multipoint ground motion by using actual earthquake records was developed.The methods suggested can be used for multi-support excitation analysis of structures.

Abstract: The invention discloses a multipoint ground-connection current control device for three current transformers to monitor transformer clamping parts in an online mode. The multipoint ground-connection current control device solves the problem that a power-cut current limiting operation method for ground-connection current of the transformer clamping parts in the prior art can affect normal operation of a power grid. A clamping part ground-connection outgoing line (9) penetrates through a coil of the first current transformer (10) to be connected with the input end (21) of a switching circuit, the two ends of the secondary side induction coils of the three current transformers are respectively connected with two input ports of an AD conversion port circuit, the output end of the AD conversion port circuit (15) is connected with a single chip microcomputer (17), the output end (22) of the switching circuit is connected with the ground-connection end (6), impedance units, used for limiting current impedance units, of three switching branches use bidirectional thyristors to control the branches to be turned on and off, and an impedance branch can be controlled to be turned on and off by controlling a conduction angle to achieve the purpose of switching the impedance units. The multipoint ground-connection current control device is high in operability and guarantees normal safety operation of the power grid.

Abstract: The utility model relates to a multipoint ground bus bar, wherein the bus bar is of a rectangular sheet shape, the two ends are respectively provided with a fixing device for fixing the multipoint ground bus bar on a cabinet; the inside of the fixing devices at the two ends of the bus bar is respectively provided with a ground wire connecting device for connecting a circular ground net; and the position between the two ground wire connecting devices on the bus bar is provided with at least 15 equipment ground connecting devices which are used for connecting the cabinet and equipment multipoint ground connecting wires in the cabinet. The multipoint ground bus bar can be fixed on the cabinet through the fixing devices; the ground wire connecting devices are used for connecting the circular ground net through wires; the equipment ground connecting devices are used for connecting the cabinet and the ground wires of equipment through wires; therefore, the cabinet and the ground wires of equipment can be connected to the circular ground net through the multipoint ground bus bar.