As for XLPE cable testing, if XLPE is used for insulation in the switchgear, the cross linking will be treed by HV DC and permanently destroyed. For this reason, HV DC is no longer used for XLPE cable testing. The switchgear should have a power frequency withstand test only and not HV DC. Refer to the relevant switchgear standard for the applied rms voltage. Any XLPE insulation will need to be replaced as it is most likely has been damaged by treeing of the cross linkages in the insulation. A maximum of say 2.5 kV DC is allowed for IR and PI only.<\/p>\n
Humidity plays important part in flashover. We faced a problem of flashovers in Air insulated 11kV Switchgear busbar compartments in rainy seasons. Any sharp edge will ionize the surrounding air, which becomes conductive to high voltage discharge. Moisture will hasten the process of discharge. During HV test also this aspect should be kept in mind.<\/p>\n
And make sure the following:
\nClean all the supporting bus insulators and spouts with CRC spray.
\nEnsure the earth bus continuity and its connection with the earth grid.
\nall PTs are taken out.
\nall CT ckt output shorted at the panel.
\nAll LAs are disconnected
\nConduct a general cleaning of busbars through CRC-sprays.
\nMegger the bus bar with 5KV between phases, and between phase to earth for 1 mints before HV test.
\nEnsure the earth bus continuity and its connection with the earth grid.
\nUse AC high voltage test preferably
\nConnect HV test kit body ground to the SWGR body ground.
\nApply 80% of the power frequency voltage applied at the FAT test.
\nIf you are doing with AC hv kit then this may be a larger unit and leakage current is exceeding and tripping.
\nTry for smaller sections of busbars\/increase the leakage current if options are available.
\nRate of rise of voltage should be in steps of 2KV\/s and gradual.
\nCheck tripping function of the test kit.
\nApply voltage betweenL1-(L2+L3)=G-1mints
\napply voltage in the same way between other phases also.
\nIf it withstands ok alternately you have to go for individual inspection of the insulators\/spouts.<\/p>\n","protected":false},"excerpt":{"rendered":"
As for XLPE cable testing, if XLPE is used for insulation in the switchgear, the cross linking will be treed by HV DC and permanently destroyed. For this reason, HV DC is no longer used for XLPE cable testing. The switchgear should have a power frequency withstand test only and not HV DC. Refer to the relevant switchgear standard for the applied rms voltage. Any XLPE insulation will need to be replaced as it is most likely has been damaged by treeing of the cross linkages in the insulation. A maximum of say 2.5 kV DC is allowed for IR and PI only.<\/p>\n
Humidity plays important part in flashover. We faced a problem of flashovers in Air insulated 11kV Switchgear busbar compartments in rainy seasons. Any sharp edge will ionize the surrounding air, which becomes conductive to high voltage discharge. Moisture will hasten the process of discharge. During HV test also this aspect should be kept in mind.<\/p>\n
And make sure the following:
\nClean all the supporting bus insulators and spouts with CRC spray.
\nEnsure the earth bus continuity and its connection with the earth grid.
\nall PTs are taken out.
\nall CT ckt output shorted at the panel.
\nAll LAs are disconnected
\nConduct a general cleaning of busbars through CRC-sprays.
\nMegger the bus bar with 5KV between phases, and between phase to earth for 1 mints before HV test.
\nEnsure the earth bus continuity and its connection with the earth grid.
\nUse AC high voltage test preferably
\nConnect HV test kit body ground to the SWGR body ground.
\nApply 80% of the power frequency voltage applied at the FAT test.
\nIf you are doing with AC hv kit then this may be a larger unit and leakage current is exceeding and tripping.
\nTry for smaller sections of busbars\/increase the leakage current if options are available.
\nRate of rise of voltage should be in steps of 2KV\/s and gradual.
\nCheck tripping function of the test kit.
\nApply voltage betweenL1-(L2+L3)=G-1mints
\napply voltage in the same way between other phases also.
\nIf it withstands ok alternately you have to go for individual inspection of the insulators\/spouts.<\/p>\n","protected":false},"author":0,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[67],"tags":[],"class_list":["post-14093","post","type-post","status-publish","format-standard","hentry","category-iacdrive_blog"],"_links":{"self":[{"href":"http:\/\/iacdrive.com\/index.php?rest_route=\/wp\/v2\/posts\/14093","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/iacdrive.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/iacdrive.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"replies":[{"embeddable":true,"href":"http:\/\/iacdrive.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=14093"}],"version-history":[{"count":0,"href":"http:\/\/iacdrive.com\/index.php?rest_route=\/wp\/v2\/posts\/14093\/revisions"}],"wp:attachment":[{"href":"http:\/\/iacdrive.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=14093"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/iacdrive.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=14093"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/iacdrive.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=14093"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}