IEEE Std C37.122.7 pdf free download

IEEE Std C37.122.7 pdf free download.Field Testng of Gas-Insulated Substatons Rated Above 52 kV.
4. Field testing in accordance with IEEE Std C37.122™ 4.1 Introduction In most cases, field tests performed on newly installed gas-insulated substation (GIS) are not repeats of the factory tests, but rather tests required to confirm that both the GIS has been assembled properly at site, and that there is no damage caused by shipping or installation. This guide will describe the tests required on the newly installed GIS systems, why these feld tests are performed, and why certain tests are repeated in the feld when they were already completed in the factory. Following the discussion of the individual tests, certain best practices will be described that will assist the testing effort in dealing with unique situations or typical questions commonly encountered during feld testing of GIS. Please refer to the feld-testing clause, in IEEE Std C37.122.1™ for additional information. 11 4.2 Mechanical tests: Leakage 4.2.1 Introduction This test is performed to demonstrate that there are no gas leaks at the field assembled joints of the GIS. Leaks may occur during field assembly as a result of the following: — Sealing surface damage — Improper placement, damage or omission of seals — Improper application of lubricants and sealants — Improper alignment and tightening of the mating surfaces — Contamination Typically, leakage through the walls of gas compartments, or at other joints that were assembled at the factory, is not a concern because they were already tested at the factory—the exception being if damage occurred during transportation and assembly, or if feld repairs were made. Factory leak testing is covered in 8.4 of IEEE Std C37.122™-2021. If factory joints were disassembled for any reason during feld assembly, these joints should be tested again. Prior to flling the GIS gas compartments with insulating gas, some manufacturers require a vacuum rise test be performed to verify moisture levels within the gas compartment. If a vacuum rise test is required by the manufacturer, its results may identify a substantial leak prior to flling the gas compartment with insulating gas.Upon completion of flling the GIS gas compartment(s) with insulating gas to the manufacturer’s recommended temperature-corrected pressure as indicated on the nameplate, verifcation that no gas leaks are present should be completed by means of a portable gas leak detector. It is recommended that a portable leak detector that provides a leak rate be used. However, a standard hand-held “go/no-go” (i.e., audible) leak detector is acceptable for initial verifcation if a leak is present. Gas leaks can be irregular and are known to intermittently leak, and consequently, a leak may not be detected by quickly passing a leak detector over the area to be tested. An accumulation-type test should be considered to mitigate this issue, in which the area to be tested can be contained for a period of time, and the leak detector can then be inserted into the trapped volume for testing. See Table 1 for accumulation-type leak detection methods applicable to sulfur hexafuoride (SF 6 ) gas.IEEE Std C37.122.7 pdf download.