SU73839A1 - Isolation control device in high voltage three-phase networks - Google Patents

Description

This invention relates to devices for monitoring insulation in three-phase high-voltage networks using a three-volt method. According to the invention, to create a zero-sequence voltage, it is proposed to use one of the known zero-sequence current filters, for example, a current transformer, zero-sequence with a ring magnetic conductor or a Holmg. Rin filter, connected to a wire connecting the zero points of star-shaped voltmeters , and a three-phase tr: a “voltage transformer.

FIG. 1 and 2 are diagrams of the device in two versions. The following notation is used in the diagrams: high voltage busbars, 2-generator, 3-grounding resistance, 4-three-phase voltage transformer, 5-transformer (with magnetic shunt), 6 - isolation control voltmeters, 7- intermediate transformer with magnetic shunt.

FIG. Figure 1 shows the scheme of the proposed device with the use of a transcon term installed on it. introductory feeder.

The neutral conductor of the system includes a sec. On the winding of this transformer, used as a filter of currents of the zero sequence, those formed during the earth fault of one of the phases of the system. These currents flow along the primary side of the transformer only if the place of the earth fault is located behind

installation for control of Izachyach;

counting from the station feeding the data .y plot. The occurrence of a zero-sequence current entails a divergence of the voltmeter indications of individual phases, which increases with increasing earth fault current, i.e. with decreasing circuit resistance value.

FIG. 2 shows a diagram of the proposed device using the three current transformers included in the input, which are included in the Holmgrin circuit. This scheme is similar to the previous one. To protect the voltmeters against overload, the proposed device uses an intermediate transformer 7, which increases the voltage of the zero-sequence current filter so that with a strong increase in the short-circuit current

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saturating him

the earth took place cores.

The subject is invented and

1. A device for monitoring three-phase high-voltage isolation networks using a three-volt method, characterized in that one of the known zero-sequence current filters, for example, a zero-sequence current transformer with an annular circuit, is used to create the zero-sequence voltage.

a mag- netic wire with a Golmgrin filter included in the wire connecting the zero points of star-connected voltmeters and a three-phase transformer “apr.

2. In device no. 1, in order to protect the voltmeters from overload, the use of such a weave transformer to increase the voltage of the zero-sequence current filter so that when the current to ground is strongly increased, its core is saturated.

FIG. 2

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And the device is protected and measured