High-voltage switchgear use and fault detection - Solutions - Huaqiang

Industrial Router Crystal 3.2*2.5mm 3225 26M (26.000MHZ) 12PF 10PPM 20PPM 30PPM

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Although the corresponding inspection and inspection work has been carried out before the purchase of the high-voltage switchgear, in reality, it is inevitable that the equipment with congenital quality problems will be put into operation. In addition, due to the external force and the aging of the machine, the high-voltage switchgear is difficult to remain permanent. Safe use status. As a remedy, the user must strengthen the inspection of the high voltage switchgear. As long as the abnormality is discovered and detected in time, the accident can be avoided.
(1) The detection and use of mechanical faults shows that the mechanical failure of the switchgear has the highest proportion. This is because there are many components associated with mechanical operation, including many links in the series connection and opening circuit. Moreover, the operation of the switch is irregular, sometimes it does not operate once for a long time, and sometimes it has to be continuously operated. In addition, it is also affected by environmental changes throughout the year. Therefore, mechanical failure, especially refusal failure, has the highest probability of occurrence.
To ensure the reliability of the operating mechanism of the switchgear, it needs to be tested and verified. For example, a vacuum circuit breaker manufacturing factory often performs mechanical operations hundreds of times under the high and low operating voltages specified by the standard before leaving the factory. If there is a fault, it is processed at the factory. Secondly, all the components in the switchgear, especially the moving parts, including the fastening screws, springs and tie rods everywhere, the strength is sufficient, the structure is reliable, and it must withstand the test of long-term operation.
To ensure good electrical continuity of the electrical circuit, the performance of the components such as the closing, opening coil and auxiliary switch must be guaranteed. Because it is a series circuit, each switch, fuse and each connection in the circuit should always be in good condition, and the DC operating power supply should always be in a normal state. If the DC link is poorly insulated, a grounding or multi-point grounding may cause the switch to malfunction. If the DC link is not conducting properly or the power supply is abnormal, a refusal accident may occur.
Regardless of the manufacturer and the operating unit, the work should be done well. To minimize mechanical failures.
(II) Detection of insulation level In principle, the higher the voltage level, the more attention is paid to the selection of the insulation level. For the medium voltage level, it is often hoped that by increasing the cost, the insulation level will be slightly higher and the operation will be safer.
The national standard GB311.1-1997 recommends four impulse withstand voltage test methods. For non-self-recovery insulation-based equipment, three-time method can be used. Non-self-recovery insulation and self-recovery insulation composite insulation equipment can be used. /9 times method, and composite insulation equipment is generally 15 times. At present, the lightning impulse withstand test of the high-voltage switchgear is mostly 15 times. In fact, the minimum air size of the external insulation required by the medium-voltage equipment, for example, the outer air-insulation clearance of the l0kV-class equipment is 125mm, the impact The withstand voltage margin is large, and the test can be achieved by the 3/9 method.
In the actual test, it is also necessary to consider the products of the same insulation level, and the operation conditions in different places vary greatly. Factors affecting the reliability of electrical equipment during operation In addition to the insulation level of the equipment itself, there are overvoltage protection measures, environmental conditions, operating conditions and aging of equipment over time, etc., must take into account the role of these factors.
(III) Conductive loop detection Conductive loop faults or accidents that occur in the operating equipment indicate that once there is poor contact in the conductive loop, the problem will increase over time. The isolation plug is often equipped with a fastening spring, which is deteriorated in elasticity after being heated, so that the contact resistance is further increased until an accident occurs. To this end, the factory must also strictly test the temperature rise test in the type test. For the batch production, the temperature rise test at rated current is also used for regular or irregular sampling. Especially for large rated current switchgear, it is advisable to carry out temperature rise test verification for each product.

According to the regulations, measuring the loop resistance with a large current DC voltage drop method is a method to prevent the conduction loop accident. Since the current used in the loop resistance measurement is limited, the measurement result is acceptable, but the current-carrying accident still occurs many times during the operation. Practice has shown that this is not a very reliable approach and should not be relied upon entirely.
For the user, after the product is put into operation, it is necessary to know the current carrying capacity and stability, and ensure the reliable and safe operation of the equipment. In the initial stage of production, it is necessary to strengthen monitoring. It is especially important to monitor the operating status of the equipment when the peak load and the summer ambient temperature are high. For example, infrared temperature measurement or the like can be used to monitor the heating condition of the device, and the latent abnormal heating phenomenon can be found in time.
Conclusion: The equipment has a fault, which is generally considered to be caused by poor quality equipment and low grades. Therefore, efforts are often made to strengthen the equipment index level. In fact, indicators such as the insulation level of equipment cannot and should not be blindly strengthened. It is necessary to analyze the accident specifically, to check whether the defects occurred are universal, and on the other hand, to work in relay protection and operating environment. Received twice the result with half the effort. We should use and reasonably detect the switchgear to ensure its reliability in terms of insulation, electrical conductivity, mechanical operation and breaking performance, and it can stand the test of time in long-term operation.