SU144100A1 - Device for directional selective signaling - Google Patents

Description

Devices for directional selective signaling are known with single-phase earth faults in networks with insulated or compensated neutral. These devices contain a two-winding measuring device, one winding of which is connected through a transformer and a switch to the zero-sequence current of the monitored lines.

The proposed device differs from the known ones in that it allows not only to determine the direction of currents in the lines, but also to measure the magnitude of the earth fault current in the damaged line. This is achieved by the fact that the second winding of the measuring device is connected to the current of the tripler h :: 1 of the voltage supplied from the voltage regulator.

The principle of operation of the device is based on the use of capacitive earth fault current or in a system with a compensated nji inductive current sweep of overcompensation, using a zero-sequence current filter. A set of current autotransformers was used as a filter.

FIG. 1 is a schematic diagram of the device; in fig. 2 - the appearance of the measuring device.

The device contains a measuring device /, autotransformers. 2 current by the number of lines, switch 3, which connects the device in turn to all controlled lines, phase control 4, key 5 controlling the phase control and frequency tripper 6.

The current autotransformer is used to power the measuring device, which is used as a power meter, with a zero in the ceiv dy of the scale (Fig. 2). The three-phase phase regulator 4 is designed to power the watt meter current circuit and to change the phase of this circuit.

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The frequency treater is used to measure (with the help of the measuring device 1) the triple frequency current, flowing through it, in the neutral conductor when a single-phase earth fault occurs.

The device works as follows.

When a single phase is connected to earth in a system, a current flows in the neutral conductor, the direction of which depends on the location of the circuit. The current in the line that has damage will flow in the opposite direction to the current of the intact lines. The operation of the device is based on a comparison of the magnitudes and directions of the currents in the neutral wire of the current filters. In the absence of insulation damage in the system, unbalance current flows in the neutral conductor, the magnitude and shape of the current curve of which is established for this system.

When a ground fault occurs, which is determined by the usual insulation monitoring devices, the key 5 controlling the phase regulator is turned on at the substation and by means of switching the switch 3, a damaged line is detected.

When connected to a damaged line, the instrument arrow will indicate the scale “line, when connected to a serviceable line, the deviation of the arrow will be insignificant in the direction of the x system.

By changing the phase of the current in the current circuit of the wattmeter with the phase regulator, it is possible to measure the magnitude of the earth fault current in the damaged line, by direct reading on the instrument slit /.

Since the magnitude and phases of the ground-fault current depend on the completeness of the circuit, supplying the current winding of the wattmeter with a constant current and combining its phase with the phase of the ground fault current through the ground (using a phase regulator), you can measure the current closures.

Subject invention

A device for directional selective signaling with single-phase ground closures in networks with an isolated or compensated neutral, containing a two-winding measuring device, one winding of which is connected through a transformer and a switch to a current of zero succession, 1 of controlled lines, that is not the magnitude of the circuit current to earth in the damaged line; the second side of the instrument is fed through a frequency tripler from the voltage regulator.

LAN

2206