Causes and Countermeasures of Discharge in High Voltage Switchgear

Reasons for discharge of high voltage switchgear:

1.The insulation structure is unreasonable. The unreasonable insulation structure is a frequent problem in the transportation and manufacturing process of high voltage switchgear. The most common problem is that the insulation structure contains impurities, burrs, air bubbles, and contamination. These unreasonable insulation structures can lead to uneven distribution of the electric field inside the insulator of the high voltage switchgear, and partial discharges are prone to occur in places where the insulation is weak. Partial discharge can still cause partial damage to the insulating medium. If the partial discharge phenomenon is not alleviated in time and continues to develop, it will cause the electrical insulation performance to drop sharply and cause the penetration breakdown of the insulation structure of electrical equipment.

2.The installation process is unreasonable. When the high voltage switchgear is installed, the gap left between the outer skirt of the current transformer and the insulating plate will provide favorable conditions for the partial discharge of the high voltage switchgear.The encapsulation of the heat-shrinkable shield of the cable room is not standardized, the insulation heat-shrinkable sleeve and the installation are not standardized, and the edge of the insulator and the sleeve will generate floating potential discharge.The screws are tightened irregularly, and the screw grows too many than nuts after tightening; the heat shrinkable cover box is not tightly sealed, and the discharge phenomenon is easy to occur after opening; the busbars of the transformer boxes in the antenna box are arranged at one time, the radius of curvature is large, and the chamfer is not Specifications, can not meet the safe return, greatly improve the possibility of corona discharge; at the same time, the environment in the high voltage chamber is harsh, and the insulating materials are prone to physical and chemical changes, which will have adverse effects on electrical performance. All of the above unreasonable installation processes can cause partial discharge in the high-voltage switchgear.

3. The operating conditions are complex. Although the high voltage switchgear is equipped with a heater, if the switchgear is located in a harsh environment, with frequent rainfall, high air humidity, and the switch is exposed to a humid environment for a long time, the performance of the internal insulating material will gradually deteriorate over time. Conductive substances or corrosion may be formed on the surface of the insulator, which increases the possibility of pollution flashover, which may easily lead to insulation accidents.

Countermeasures for high-voltage switchgear discharge:

1. Standardize material selection and installation. When installing and processing busbars and processing copper bar chamfers, operate in strict accordance with relevant specifications. Optimizing the electrode shape increases the electrode curvature radius to achieve a uniform distribution of the electric field, thereby enhancing the breakdown voltage of the gap. In order to avoid the local electric field being too concentrated, when the busbar is overlapped, the exposed part of the fixing bolt should not exceed 3 teeth on the outside, and the overlapped part of the busbar should ensure that the overlapped surface is flush. When choosing a shielding contact box, it is best to choose a contact box with a shielding design to achieve the purpose of evenly distributing the electric field and preventing excessive concentration of the electric field. For enhanced antifouling, it is best to choose a casing with a dual screen design.

2. Control insulation defects. The reliability of the power supply equipment is determined by the performance of the insulation structure of the electrical equipment. In order to maximize the insulation performance of the electrical equipment and control the insulation defects, the insulation board inside the high voltage switchgear should be painted with anti-fouling and moisture-proof paint to increase the Hydrophobicity of insulating panels. When choosing the busbar insulation bushing, try to choose products produced by qualified manufacturers with good quality and reputation. When checking the encapsulation, it is necessary to pay attention to whether there is no air gap and whether the shrinkage is uniform. The busbar insulating sleeve without air gap and uniform shrinkage can greatly improve the stable performance of the busbar, and also effectively improve the insulation performance of the switch cabinet and corrosive properties.

3. Optimize operating conditions. In order to avoid the operating failure of the high voltage switchgear caused by the environment, the power unit should improve the operating environment of the high-voltage switchgear. When the temperature is high, in order to dissipate the heat of the switchgear in time, fans should be installed before and after the handcart cabinet or on the upper and lower cabinets. After the busbar cabinet, the lower cabinet is filled with cooling holes to strengthen the air convection, so as to facilitate the ventilation and heat dissipation of the high-voltage switch cabinet, and ensure the drying of the cabinet;

In the rainy and humid season, the drainage work should be done first, and the heater should be installed in the bus room, and the heating dehumidifier should be installed in the cable room and switch room so as to achieve the purpose of effectively adjusting the temperature and humidity.and ensure that the temperature and humidity around the high voltage switchgear are all Keep it within the scope of the standard requirements; in addition, the switchgear should be cleaned up to ensure the safe and reliable operation of the high voltage switchgear.

4. Strengthen condition maintenance. The traditional maintenance mode is to use multiple maintenance teams to carry out maintenance operations on multiple maintenance surfaces at the same time, which will not only waste resources, but also cause huge economic losses. At present, with the increase of voltage level, the expansion of power grid scale and the growth of electricity load, if the power outage maintenance is carried out again, the maintenance cost will be greatly increased. Therefore, it is necessary to implement condition maintenance of high voltage electrical equipment. Condition-based maintenance can monitor the status of electrical equipment in real time, and can accurately and timely find potential hidden dangers in electrical equipment, take effective measures in time, without the need for large-scale power outages, which greatly saves maintenance costs and improves the pertinence of maintenance and repair work.

KYN28(GZS1)type moveable metal-clad switchgear is three-phase A.C 50Hz indoor distributing equipment with voltage of 3.6~12KV.lt is used for power plant to transmit power and used for electricity system, industrial and mineral enterprise to receive and distribute power, as well as to control high voltage generator which is frequently started lt can meet the standard requirements of GB3906.DL404.IEC-298 etc.And it has the function of the preventing wrong operation for circuit breakers, preventing move truck with load, prevent ingopening(closing)earthing switch with charged, preventing earthing switch transmitting power in the earthing position and preventing entering into live compartment.