The necessity of over - voltage protection of natural gas Duct Insulation
Reflected in the following two aspects: gas workers classroom
1, the ground insulation joints above the pipeline over-voltage discharge into the ground, so that over-voltage and lightning current can not enter the room, so as to protect the safety of indoor staff and reduce the interference of electromagnetic interference on indoor equipment.
2, to reduce the potential difference between the two ends of the pipe insulation flange, so that its value is reduced to the insulation resistance of the insulation within the range, to avoid over-voltage breakdown insulation, resulting in system failure, and to prevent the insulation joints were punched Arc ignition detonated natural gas pipeline.
How does zinc oxide arrester work:
Rated current through the zinc oxide arrester valve current is only very small, the equivalent of insulators. When the voltage on the metal zinc oxide arrester exceeds the set value, the valve "turns" to the high current through the valve into the ground, the residual pressure does not exceed the pressure of the protected equipment. When the action voltage drops below the operating voltage,Duct Insulation the valve automatically terminates the "on" state and restores the insulation state.
Insulation accident manufacturing defects that are divided into "sharp burr" said, "metal foreign body" said, "grain content" said. As well as "insulation defects" and so on. All these statements focus on the point that there is a consensus on the discharge mechanism, that is, the first occurrence of partial discharge, and then in the normal operating voltage caused by insulation breakdown. Earlier old transformers did have all of the above causes cause insulation under normal operating voltage, and the fact that the analysis of the discharge mechanism was realistic. But for large power transformers, this type of transformer has been running for more than 20 years,Duct Insulation there are problems should be exposed. If it has not been exposed so far, it can prove that such defects are no longer practically present. 80 years since the last century, 220kV and above the voltage level of the transformer have been partial discharge test. Experience has shown that the PD test is particularly effective in finding these defects. Therefore, for the factory to put the test of qualified transformer, especially after installation or maintenance also carried out the PD test of the transformer,Duct Insulation there is no longer in the normal operating voltage is enough to cause insulation accidents manufacturing defects. This is the magic of the PD test.
I have experienced several transformers, due to oil blockage,Duct Insulation turn insulation local overheating, causing the normal operating voltage of the turn insulation accident. In fact it was overheating. Oil gas chromatographic analysis (DGA) is an identification of such accidents.
China's large-scale power transformers are all sealed structure, running time is not long, a lot of young and loaded So there is generally no problem of insulation aging. If insulation caused by insulation caused by accident,Duct Insulation there will be a clear symbol of aging. For the insulation accident disassembly overhaul of multiple transformers, had to check the degree of aging, there is no evidence from the aging phenomenon to find evidence. Insulation aging phenomenon is specific and obvious, there is evidence to be established, otherwise it should rule out its possibility.