SU45982A1 - Device for the protection of electrical installations - Google Patents

Description

The present invention relates to devices for protecting electrical installations from single-phase earth faults and overvoltages, consisting of a selective relay system controlling switches that automatically ground the affected circuit across the phase conductor and the resistance of the neutral grounding of the high-voltage transformer and made of a substance that reduces its resistance with increasing voltage. In the proposed device according to the invention, in order to use disconnectors as said switches, by releasing them from the work of opening the current of a single-phase earth fault, an oil switch connected to disconnectors is switched on in series with the indicated resistance. one of the disconnectors.

The proposed device is shown schematically in the drawing.

The neutral point of the high-voltage transformer 7 is grounded through the resistance of the nitrite and single-phase oil switch 3. Any of the phase conductors of the line can be grounded through the disconnector 5 and the constant resistance 4. Disconnectors 5 and the oil switch 3 are

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UNDER control of a selective relay system for single-phase short-circuits.

Normally, the disconnectors 5 are open and the switch 3 is closed. When any phase closes to earth, the corresponding disconnector 5 is instantly turned on (by the mentioned relay system), and then the oil switch 3 turns off, which takes on the job of turning off the full-phase single-phase short circuit of the line. After a short run out of time, it is necessary to manually switch off the disconnector 5 and, in the event of a ground fault, turn off switch 3.

The proposed device does not increase the risk of damage to the insulation of the transformer during lightning discharges, since the resistance 2 does not exceed 1 ohm at high voltages. Normally, a very small current flows through resistance 2, since the usual zero-point voltage relative to the earth does not exceed 1-2% due to unbalance, and at such small voltages the resistance of tirith is very high.

If any phase is grounded through an arc, the last is most likely to pass after switching off the switch 5. No overvoltages at

-. . . - -J

that's for me. will be due to the included resistance 4 and disconnector 5. Joti Disconnect switch 5 may be either zero or zero (in case of a deafened phase) or several amperes of capacitive current in case of insulation recovery. This current is quite possible to turn off the disconnector.

After disconnecting switch 5 is turned off, switch J should be switched on immediately in case of ground loss. E (; whether grounding remains;), you can leave switch 3 open until the line is corrected, and at this time bring the electrodes of the coordinating spark gap closer together.

The subject invention.

Device to protect electrical installations from single-phase locking .....: -,.

Scientific research institutes to the ground and from the power supplies, consisting of a selective relay system that controls the switches, automatically grounded the phase np i ip affected by the earth fault, and of the resistance, grounding the neutral of the high voltage t: anformator and made of the substance resistance during voltage boosting, characterized in that, in order to use disconnectors as specified switches by freeing them from the work of opening the current of a single one-way earth fault, sequentially with the indicated resistance, the oil switch 3 is on, interlocked with disconnectors 5, so that it is turned off after one of the disconnectors is turned on.

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