Describe

In order to effectively limit the over-voltage and non arc suppression of hg-3-kv power supply system, and effectively eliminate the over-voltage and non arc suppression of single-phase grounding system.

Harm of single-phase arc grounding overvoltage.

China's 3-35kv (including 66kV) power grid mostly adopts the neutral ungrounded operation mode. When single-phase metallic direct grounding occurs in such power grids, the non fault phase to ground voltage will rise to the line voltage, the three-phase line voltage will remain unchanged, and there is still a 120 ° phase difference. The operation of three-phase electrical equipment is not affected, so it will not affect the normal transmission of electric energy. Therefore, the national standard stipulates that this kind of power grid can operate with fault for a short time after single-phase grounding fault, which improves the reliability of power supply of this kind of power grid.

According to the existing operation regulations, when a single-phase grounding fault occurs in the neutral non effectively grounded system, it is allowed to operate for two hours, but the regulations are not correct for & ldquo; Single phase grounding fault & rdquo; The concept of is clearly defined. If the single-phase grounding fault is gold fan grounding, the voltage of the fault phase will drop to zero, and the phase to ground voltage of the remaining two sound will rise to the line voltage. Under normal conditions, the electrical equipment of this kind of power grid shall be able to withstand this overvoltage without damage to the surface. However, if the single-phase grounding is intermittent arc grounding, an overvoltage up to 3.5 times the peak phase voltage will be generated in the system. If such a high overvoltage acts on the power grid for several hours, it is bound to cause cumulative damage to the insulation in the electrical equipment, cause insulation to ground breakdown in the weak insulation link of the sound phase, and then develop into phase to phase short circuit accident, In the transient process of intermittent arc grounding, the actual system will form a multi frequency oscillation circuit, which will not only produce phase-to-phase overvoltage with high amplitude, flashover the weakness of phase-to-phase insulation, and develop into phase-to-phase short-circuit accident.

Arc suppression effect of resonant grounding mode

With the large-scale technological transformation of urban and rural power grids in China, the distribution networks in urban and rural areas must be oriented and cabled. The system capacitance current to ground is gradually increasing, and the problem of arc grounding overvoltage is becoming more and more serious. In order to solve the above problems, many power grids adopt resonant grounding mode, that is, arc suppression coil is installed in the power grid, When single-phase arc grounding occurs in the system, the inductive current generated by arc suppression coil is used to compensate the capacitive current at the fault point Reduce the residual current flowing through the fault point So as to achieve natural arc extinguishing. The actual operation experience shows that the equipment damage caused by single-phase arc grounding overvoltage and the accidents affecting the operation safety of the system still occur from time to time in the power grid with the neutral grounded through the arc suppression coil. The reason is that due to the diversification of power grid operation mode and the randomness of arc grounding point, it is difficult for arc suppression coil to effectively compensate the capacitive current, and arc suppression coil only compensates the power frequency capacitive current The actual current passing through the grounding point is not only the power frequency capacitor current It also contains a large amount of high frequency current and resistive current In severe cases, only high-frequency current and resistive current can maintain the suspected combustion of arc. Even in some cases, due to the existence of arc suppression coil, arc re ignition may occur at the most unfavorable time when the recovery voltage is the maximum, resulting in the rise of arc grounding overvoltage

With the development of urban and rural power grids and the increasing requirements of production and life for power supply reliability, the harm and spread caused by each insulation accident are bound to increase Therefore, our company has developed XHG arc suppression, harmonic elimination and voltage protection device to limit the phase to ground and phase-to-phase overvoltage of neutral non effectively grounded power grid within the scope of safe operation of power grid, completely solve the threat of various overvoltage to the safe operation of equipment and power grid, and improve the power supply reliability of this kind of power grid.

Product model and meaning

Service environmental conditions

1. Altitude: no more than 2000m;

2. Ambient temperature: - 25 ℃ - + 40 ℃;

3. Relative humidity: the daily average relative humidity is not more than 95%, and the monthly average relative humidity is not more than 90%;

4. Seismic intensity: no more than 8 degrees;

5. Places without fire, explosion hazard, serious pollution, chemical corrosion and violent vibration;

6. Indoor use.