What are the Basic Standards to be Followed when Overhauling High-voltage Switches?
In modern electrical power systems, circuit breakers play a vital role in ensuring the reliability and safety of power distribution. Regular maintenance and comprehensive testing are essential to guarantee that these devices operate effectively under various conditions. Overhauling circuit breakers involves not only mechanical inspections but also stringent testing of their electrical components, particularly those involving SF6 gas, which is critical for insulation and arc extinction. Adhering to industry standards and manufacturer specifications during testing helps to identify potential failures and ensures the longevity and reliability of circuit breakers in service.
SF6 Gas Moisture Content Test for Circuit Breakers
After overhauling the arc extinguishing chamber, the moisture content should not exceed 150μL/L; for other gas chambers, it should not exceed 250μL/L.
SF6 Gas Leak Test
The annual leakage rate should not exceed 1%.
Insulation Resistance of Auxiliary and Control Circuits
Using a 500V or 1000V megohmmeter, the insulation resistance should not be less than 2MΩ.
AC Voltage Withstand Test
The test voltage should be 80% of the factory test voltage, with a withstand time of 1 minute.
AC Voltage Withstand Test for Auxiliary and Control Circuits
The test voltage should be 2kV, and the insulation resistance should not decrease after 1 minute of withstand.
Circuit Breaker Speed Characteristics
The measurement method and results should comply with manufacturer specifications.
Time Parameters of the Circuit Breaker
Unless otherwise specified by the manufacturer, the synchronization of opening and closing times should not exceed 5ms for phase closing and 3ms for phase opening.
Actuation Voltage of Opening and Closing Electromagnets
The minimum actuation voltage of the opening and closing electromagnets or closing contacts should be between 30% and 65% of the rated operating voltage. (Manufacturer's standard: reliable closing actuation voltage range is 80% to 110% Un; reliable opening actuation voltage range is 65% to 120% Un, with the minimum actuation voltage below 30% not actuating.)
Resistance of Conductive Circuit
Measured using the direct current voltage drop method, with a current of not less than 100A. The measured value for open circuit breakers should not exceed 120% of the manufacturer's specified value.
DC Resistance of Opening and Closing Coils
Must comply with manufacturer specifications.
SF6 Gas Density Monitor Inspection
According to manufacturer specifications.
Calibration of Pressure Gauges and Mechanical Safety Valves
According to manufacturer specifications.
Leakage Test of Hydraulic Operating Mechanism
According to manufacturer specifications.
In conclusion, conducting thorough testing during the overhaul of circuit breakers is crucial to maintaining their performance and reliability. Each test item outlined in this document is designed to assess various aspects of the circuit breaker's functionality, ensuring that all components meet the required safety and operational standards. The careful monitoring of SF6 gas levels, insulation resistance, and mechanical integrity helps to preemptively identify issues that could lead to failures in the field. By adhering to these testing protocols, utility companies and maintenance personnel can significantly enhance the reliability of their power distribution systems, thereby ensuring the continued safe and efficient delivery of electricity. The importance of regular overhauls and testing cannot be overstated, as they are fundamental to the long-term success and sustainability of electrical infrastructure.
Tap Changer Timer & Analyzer--JYK-II(Kingrun)
