Diagnosis And Handling Of Abnormal Hydraulic Pressure In Sf6 Circuit Breaker Operating Mechanism

In the actual operation and maintenance of power systems, pressure fluctuations in the hydraulic system of sf6 circuit breaker operating mechanism are a relatively common equipment hazard. Abnormal pressure not only affects the opening and closing speed of circuit breakers, but in severe cases, it can even lead to equipment failure to operate or slow opening accidents. Based on field experience, we have summarized the typical causes and key points for troubleshooting abnormal pressure in hydraulic mechanisms.

Two Typical Manifestations of Abnormal Pressure

Abnormal pressure in hydraulic mechanisms usually manifests as excessively high or low oil pressure. The underlying fault mechanisms for these two situations are completely different.

Excessively high oil pressure is often related to control system malfunction. When the oil pump motor continuously pressurizes without stopping, and the pressure gauge pointer exceeds the rated value, it is mostly due to damage to the "oil pump stop" microswitch contacts or a misalignment. Failure of the internal seal of the energy storage tank, allowing high-pressure oil to enter the nitrogen side, can also cause an abnormal increase in pre-pressure. In this case, the energy storage power supply should be disconnected immediately to prevent the pressure from continuing to rise and damaging structural components.

Excessively low oil pressure often indicates hydraulic oil leakage. Besides visible oil seepage in high-pressure pipelines, more troublesome are hidden leaks inside the mechanism. Internal pressure loss can occur when impurities in the valve system cause it to be "padded" by oil or when the seals are damaged. For example, during the maintenance of a 500kV circuit breaker, it was found that residual iron filings in the oil chamber caused the plunger to not seal properly, resulting in repeated pressure loss and failure to build up pressure.

Details for Troubleshooting Internal Leaks

When dealing with internal leaks, maintenance personnel need to pay attention to several points. High-pressure oil leaks often produce a slight hissing sound, which can be used to locate the leak by listening. When disassembling and inspecting the valve body, valve lines with slight marks need to be ground, and deformed or damaged valve needles must be replaced. Hydraulic oil contamination is a major cause of seal failure; it is recommended to filter or replace No. 10 aviation hydraulic oil according to the specified cycle (e.g., every 2 years).