{"id":1908,"date":"2026-07-06T08:01:52","date_gmt":"2026-07-06T08:01:52","guid":{"rendered":"https:\/\/zeeyielec.com\/?p=1908"},"modified":"2026-07-06T08:02:59","modified_gmt":"2026-07-06T08:02:59","slug":"mv-bushing-installation-torque-control-checklist","status":"publish","type":"post","link":"https:\/\/zeeyielec.com\/pt\/mv-bushing-installation-torque-control-checklist\/","title":{"rendered":"Lista de verifica\u00e7\u00e3o para instala\u00e7\u00e3o de buchas MV e controle de torque"},"content":{"rendered":"<p>Esta lista de verifica\u00e7\u00e3o para controle de torque na instala\u00e7\u00e3o de buchas de m\u00e9dia tens\u00e3o aborda a interface de veda\u00e7\u00e3o, as etapas de aplica\u00e7\u00e3o do torque e os procedimentos de diagn\u00f3stico que determinam se uma bucha de m\u00e9dia tens\u00e3o resiste aos ciclos t\u00e9rmicos e \u00e0s tens\u00f5es el\u00e9tricas ao longo de d\u00e9cadas de servi\u00e7o.<\/p>\n\n\n\n<p>Torque control is not a formality in MV bushing installation \u2014 it&#8217;s the mechanism that determines whether the sealing interface holds under thermal cycling and electrical stress over decades of service. An under-torqued flange leaves microscopic gaps at the gasket interface, and an over-torqued one can crack porcelain housings or deform epoxy resin systems. Both shorten service life in ways that often don&#8217;t show up until months after commissioning.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Por que o controle de torque \u00e9 importante na instala\u00e7\u00e3o de buchas para ve\u00edculos de m\u00e9dio porte<\/h2>\n\n\n\n<p>The bushing-to-turret interface relies on a gasket (typically nitrile or EPDM) achieving uniform compression across its full circumference. Insufficient compression \u2014 generally below the manufacturer&#8217;s minimum specified force \u2014 allows moisture ingress that accelerates partial discharge (PD) activity at the flange. In field commissioning work, technicians commonly find bushings that &#8220;look&#8221; seated but fail an insulation resistance test simply because one quadrant of the gasket never reached proper compression, a reminder that visual inspection alone isn&#8217;t a substitute for torque verification.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Compress\u00e3o da junta e interface de veda\u00e7\u00e3o<\/h3>\n\n\n\n<p>Os di\u00e2metros t\u00edpicos dos parafusos de flange para buchas de m\u00e9dia tens\u00e3o variam de 12 mm a 20 mm (M12\u2013M20), com especifica\u00e7\u00f5es de torque que geralmente ficam entre 40 N\u00b7m e 110 N\u00b7m, dependendo da classe do parafuso e do material da flange. Sempre consulte a tabela de torque do fabricante original (OEM) em vez de aplicar um valor gen\u00e9rico.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Preserva\u00e7\u00e3o da dist\u00e2ncia de fuga e da dist\u00e2ncia de isolamento sob tens\u00e3o mec\u00e2nica<\/h3>\n\n\n\n<p>Over-torquing can also distort the mounting flange, subtly reducing creepage distance between the bushing&#8217;s live end and grounded turret metal. This matters most for outdoor MV bushings rated 15 kV to 38 kV class, where creepage margins are already tight relative to contamination severity.<\/p>\n\n\n\n<p>A distribui\u00e7\u00e3o de tens\u00e3o na flange pode ser estimada, sendo que a for\u00e7a de compress\u00e3o F \u00e9 aproximadamente proporcional ao torque aplicado T, ao coeficiente de atrito da junta \u03bc e ao di\u00e2metro do c\u00edrculo de parafusos d: <em>F \u2248 T \/ (\u03bc \u00d7 d)<\/em>. Essa rela\u00e7\u00e3o explica por que as mudan\u00e7as no estado de lubrifica\u00e7\u00e3o dos parafusos resultaram em for\u00e7a de fixa\u00e7\u00e3o mesmo com leituras id\u00eanticas da chave de torque.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"559\" src=\"https:\/\/zeeyielec.com\/wp-content\/uploads\/2026\/07\/zeeyielec-mv-bushing-installation-torque-control-checklist-figure-01.webp-1024x559.webp\" alt=\"Diagrama em corte transversal da compress\u00e3o da junta da flange do buch\u00e3o de MT e do percurso da for\u00e7a de torque\" class=\"wp-image-1910\" srcset=\"https:\/\/zeeyielec.com\/wp-content\/uploads\/2026\/07\/zeeyielec-mv-bushing-installation-torque-control-checklist-figure-01.webp-1024x559.webp 1024w, https:\/\/zeeyielec.com\/wp-content\/uploads\/2026\/07\/zeeyielec-mv-bushing-installation-torque-control-checklist-figure-01.webp-300x164.webp 300w, https:\/\/zeeyielec.com\/wp-content\/uploads\/2026\/07\/zeeyielec-mv-bushing-installation-torque-control-checklist-figure-01.webp-768x419.webp 768w, https:\/\/zeeyielec.com\/wp-content\/uploads\/2026\/07\/zeeyielec-mv-bushing-installation-torque-control-checklist-figure-01.webp-1536x838.webp 1536w, https:\/\/zeeyielec.com\/wp-content\/uploads\/2026\/07\/zeeyielec-mv-bushing-installation-torque-control-checklist-figure-01.webp-2048x1117.webp 2048w, https:\/\/zeeyielec.com\/wp-content\/uploads\/2026\/07\/zeeyielec-mv-bushing-installation-torque-control-checklist-figure-01.webp-18x10.webp 18w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">Vista transversal da interface entre a bucha e o flange, mostrando como o torque aplicado se traduz em for\u00e7a de compress\u00e3o da junta ao longo do c\u00edrculo de parafusos.<\/figcaption><\/figure>\n\n\n\n<p>Para obter um contexto mais amplo sobre a constru&ccedil;&atilde;o de buchas, consulte o artigo da ZeeyiElec &lt;a href=&quot;\/pt\/&rdquo;https:\/\/zeeyielec.com\/transformer-accessories\/medium-voltage-bushings\/&rdquo;\/&quot;&gt;buchas de m&eacute;dia tens&atilde;o&lt;\/a&gt; p&aacute;gina da s&eacute;rie.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">Insights de especialistas<\/h4>\n\n\n\n<ul class=\"wp-block-list\">\n<li>A inspe\u00e7\u00e3o visual nunca confirma o torque \u2014 uma junta pode parecer uniforme e, mesmo assim, estar com compress\u00e3o insuficiente em um dos quadrantes<\/li>\n\n\n\n<li>O pr\u00f3prio estado de lubrifica\u00e7\u00e3o do parafuso pode alterar a for\u00e7a de fixa\u00e7\u00e3o em 15-20%, mesmo com a mesma leitura de torque<\/li>\n\n\n\n<li>Creepage loss from flange distortion often isn&#8217;t visible until a PD test flags it<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Lista de verifica\u00e7\u00e3o para inspe\u00e7\u00e3o pr\u00e9-instala\u00e7\u00e3o<\/h2>\n\n\n\n<p>Antes que qualquer chave dinamom\u00e9trica entre em contato com um parafuso, a bucha, a junta e o flange de montagem precisam ser aprovados em uma inspe\u00e7\u00e3o documentada. Ignorar essa etapa \u00e9 uma das causas mais comuns identificadas durante chamadas de suporte t\u00e9cnico \u2014 uma superf\u00edcie de veda\u00e7\u00e3o arranhada ou uma junta deixada em uma caixa \u00famida durante a noite pode comprometer uma sequ\u00eancia de torque que, de outra forma, seria perfeita durante a instala\u00e7\u00e3o da bucha MV.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Inspe\u00e7\u00e3o da superf\u00edcie da bucha e da porcelana\/ep\u00f3xi<\/h3>\n\n\n\n<p>Inspect the full length of the bushing for hairline cracks, chips at the flange seat, or contamination film. Porcelain bushings should be checked under raking light for surface crazing; epoxy resin bushings need a check for chalking or UV degradation if they&#8217;ve been in outdoor storage. Reject any bushing with visible damage within 5 mm of the sealing groove \u2014 a small chip there is enough to compromise gasket seating.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Condi\u00e7\u00e3o da junta e do flange de montagem<\/h3>\n\n\n\n<p>As juntas devem ser verificadas quanto \u00e0 deforma\u00e7\u00e3o permanente causada pelo empilhamento durante o armazenamento anterior e rejeitadas se a espessura tiver diminu\u00eddo em mais de aproximadamente 10-15% em rela\u00e7\u00e3o ao valor nominal. As superf\u00edcies das flanges no lado da torre devem ser verificadas quanto \u00e0 presen\u00e7a de corros\u00e3o por pite, res\u00edduos de juntas antigas ou ac\u00famulo de tinta superior a 0,1 mm a 0,2 mm, uma vez que mesmo camadas finas de revestimento alteram a altura efetiva de fixa\u00e7\u00e3o na junta.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">An\u00e1lise de contamina\u00e7\u00e3o e umidade<\/h3>\n\n\n\n<p>Em locais costeiros ou com alta umidade, os t\u00e9cnicos costumam limpar ambas as superf\u00edcies de contato com \u00e1lcool isoprop\u00edlico imediatamente antes da montagem, uma vez que camadas residuais de umidade t\u00eam sido associadas \u00e0 atividade de descarga parcial (PD) no in\u00edcio da vida \u00fatil durante os testes de comissionamento. Umidade ambiente acima de aproximadamente 85% de umidade relativa (RH) \u00e9 um fator comum que leva ao adiamento da instala\u00e7\u00e3o, especialmente no caso de buchas ep\u00f3xi, nas quais a umidade superficial pode afetar a cura da resina nas \u00e1reas de retoque.<\/p>\n\n\n\nFor flange-facing hardware and compatible gasket kits, see ZeeyiElec&#8217;s <a href=\"https:\/\/zeeyielec.com\/pt\/transformer-accessories\/bushing-well-inserts\/\">inser\u00e7\u00f5es de po\u00e7o de bucha<\/a> s\u00e9rie e o <a href=\"https:\/\/zeeyielec.com\/pt\/transformer-accessories\/\">acess\u00f3rios para transformadores<\/a> p\u00e1gina principal.\n\n\n\n<h2 class=\"wp-block-heading\">Sele\u00e7\u00e3o do valor de torque por classe de bucha<\/h2>\n\n\n\n<p>Torque specifications for MV bushing flanges scale with bolt diameter, flange material, and gasket type \u2014 applying a &#8220;typical&#8221; value across bushing classes is a common source of field failures.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Classes de materiais para parafusos\/pinos<\/h3>\n\n\n\n<p>A maioria dos flanges de bucha para MV utiliza pinos de a\u00e7o inoxid\u00e1vel ou de a\u00e7o carbono zincado na classe 8.8 ou equivalentes \u00e0 A2-70. Os pinos de a\u00e7o inoxid\u00e1vel geralmente requerem valores de torque cerca de 10-15% menores do que os de a\u00e7o carbono zincado com o mesmo di\u00e2metro, devido \u00e0s diferen\u00e7as no coeficiente de atrito da rosca \u2014 algo f\u00e1cil de ignorar ao reutilizar uma tabela de torque em lotes mistos de pe\u00e7as em um trabalho de retrofit.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Faixa de torque por di\u00e2metro da flange<\/h3>\n\n\n\n<p>The following reflects general industry practice; always confirm against the specific bushing manufacturer&#8217;s datasheet before applying in the field.<\/p>\n\n\n\n<table border=\"1\" cellpadding=\"6\" style=\"border-collapse:collapse; width:100%;\"> <thead style=\"background-color:#2b4197; color:#ffffff;\"> <tr><th>Tamanho do parafuso<\/th><th>Classe de tens\u00e3o da bucha<\/th><th>Faixa t\u00edpica de torque<\/th><\/tr> <\/thead> <tbody> <tr><td>M12<\/td><td>Classe de 15 kV<\/td><td>40 N\u00b7m \u2013 55 N\u00b7m<\/td><\/tr> <tr><td>M16<\/td><td>Classe de 25 kV<\/td><td>65 N\u00b7m \u2013 85 N\u00b7m<\/td><\/tr> <tr><td>M20<\/td><td>Classe 38 kV<\/td><td>90 N\u00b7m \u2013 110 N\u00b7m<\/td><\/tr> <\/tbody> <\/table>\n\n\n\n<p>These figures assume dry, unlubricated threads. If anti-seize compound is used, torque values are typically reduced by 15-20% to achieve equivalent clamping force, since lubrication lowers the friction coefficient referenced earlier. Field crews sometimes apply the same torque regardless of lubrication state, which can lead to gasket over-compression and, in porcelain bushings, hairline flange cracking that isn&#8217;t visible until a later maintenance inspection.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"559\" src=\"https:\/\/zeeyielec.com\/wp-content\/uploads\/2026\/07\/zeeyielec-mv-bushing-installation-torque-control-checklist-figure-02.webp-1024x559.webp\" alt=\"Tabela de refer\u00eancia de valores de torque para buchas de MV, por tamanho do parafuso e classe de tens\u00e3o\" class=\"wp-image-1911\" srcset=\"https:\/\/zeeyielec.com\/wp-content\/uploads\/2026\/07\/zeeyielec-mv-bushing-installation-torque-control-checklist-figure-02.webp-1024x559.webp 1024w, https:\/\/zeeyielec.com\/wp-content\/uploads\/2026\/07\/zeeyielec-mv-bushing-installation-torque-control-checklist-figure-02.webp-300x164.webp 300w, https:\/\/zeeyielec.com\/wp-content\/uploads\/2026\/07\/zeeyielec-mv-bushing-installation-torque-control-checklist-figure-02.webp-768x419.webp 768w, https:\/\/zeeyielec.com\/wp-content\/uploads\/2026\/07\/zeeyielec-mv-bushing-installation-torque-control-checklist-figure-02.webp-1536x838.webp 1536w, https:\/\/zeeyielec.com\/wp-content\/uploads\/2026\/07\/zeeyielec-mv-bushing-installation-torque-control-checklist-figure-02.webp-2048x1117.webp 2048w, https:\/\/zeeyielec.com\/wp-content\/uploads\/2026\/07\/zeeyielec-mv-bushing-installation-torque-control-checklist-figure-02.webp-18x10.webp 18w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">Tabela de refer\u00eancia que relaciona o di\u00e2metro do parafuso e a classe de tens\u00e3o da bucha \u00e0s faixas t\u00edpicas de torque para pinos de montagem de M12 a M20.<\/figcaption><\/figure>\n\n\n\nFor compatible switching hardware often installed alongside MV bushings, see ZeeyiElec&#8217;s <a href=\"https:\/\/zeeyielec.com\/pt\/transformer-accessories\/loadbreak-switch\/\">interruptor de quebra de carga<\/a> p\u00e1gina da s\u00e9rie.\n\n\n\n<h2 class=\"wp-block-heading\">Sequ\u00eancia passo a passo para a aplica\u00e7\u00e3o do torque<\/h2>\n\n\n\n<p>Aplicar o torque final em uma \u00fanica passagem \u00e9 uma das maneiras mais r\u00e1pidas de obter uma compress\u00e3o irregular da junta, mesmo quando o valor de torque desejado est\u00e1 correto. A sequ\u00eancia e as etapas s\u00e3o t\u00e3o importantes quanto o valor indicado na chave.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Ordem de aperto em padr\u00e3o de estrela<\/h3>\n\n\n\n<p>Bolts should be tightened in a star or cross pattern rather than sequentially around the flange circumference. For a typical 8-bolt MV bushing flange, this means tightening bolt 1, then the bolt roughly opposite (bolt 5), then 3, then 7, and so on \u2014 distributing compression evenly rather than progressively &#8220;walking&#8221; the gasket into an uneven seat. Skipping this pattern is a recurring finding during troubleshooting visits, particularly on retrofit jobs where crews work from memory rather than a documented procedure.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Passagens de torque em etapas (30% \u2192 70% \u2192 100%)<\/h3>\n\n\n\n<p>Final torque should be reached in at least three passes: an initial pass at roughly 30% of target to seat the gasket, a second pass at 70%, and a final pass at 100% \u2014 always following the same star pattern each time. A fourth &#8220;check pass&#8221; at full torque, performed after the joint settles for a few minutes, catches the relaxation that naturally occurs as the gasket compresses under load. For an M16 stud in the 65 N\u00b7m to 85 N\u00b7m range, this typically means passes at roughly 20 N\u00b7m, 55 N\u00b7m, and then final torque.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Considera\u00e7\u00f5es sobre a temperatura ambiente durante o aperto com torque<\/h3>\n\n\n\n<p>Temperaturas ambientes baixas, especialmente abaixo de 0 \u00b0C, tornam os materiais das juntas mais r\u00edgidos e menos capazes de se adaptar a pequenas irregularidades nas flanges, o que pode levar a uma veda\u00e7\u00e3o insuficiente, mesmo com valores corretos de torque. Nessas condi\u00e7\u00f5es, algumas equipes realizam uma verifica\u00e7\u00e3o de reaperto assim que o transformador atinge a temperatura normal de opera\u00e7\u00e3o, uma vez que a expans\u00e3o t\u00e9rmica da flange e da junta altera ligeiramente a for\u00e7a de aperto alcan\u00e7ada em rela\u00e7\u00e3o ao estado frio no momento da instala\u00e7\u00e3o.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"559\" src=\"https:\/\/zeeyielec.com\/wp-content\/uploads\/2026\/07\/zeeyielec-mv-bushing-installation-torque-control-checklist-figure-03.webp-1024x559.webp\" alt=\"Diagrama da sequ\u00eancia de aperto dos parafusos em padr\u00e3o de estrela para flange com bucha de 8 parafusos\" class=\"wp-image-1912\" srcset=\"https:\/\/zeeyielec.com\/wp-content\/uploads\/2026\/07\/zeeyielec-mv-bushing-installation-torque-control-checklist-figure-03.webp-1024x559.webp 1024w, https:\/\/zeeyielec.com\/wp-content\/uploads\/2026\/07\/zeeyielec-mv-bushing-installation-torque-control-checklist-figure-03.webp-300x164.webp 300w, https:\/\/zeeyielec.com\/wp-content\/uploads\/2026\/07\/zeeyielec-mv-bushing-installation-torque-control-checklist-figure-03.webp-768x419.webp 768w, https:\/\/zeeyielec.com\/wp-content\/uploads\/2026\/07\/zeeyielec-mv-bushing-installation-torque-control-checklist-figure-03.webp-1536x838.webp 1536w, https:\/\/zeeyielec.com\/wp-content\/uploads\/2026\/07\/zeeyielec-mv-bushing-installation-torque-control-checklist-figure-03.webp-2048x1117.webp 2048w, https:\/\/zeeyielec.com\/wp-content\/uploads\/2026\/07\/zeeyielec-mv-bushing-installation-torque-control-checklist-figure-03.webp-18x10.webp 18w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">Sequ\u00eancia numerada de aperto em padr\u00e3o de estrela para um flange com bucha MV de 8 parafusos, garantindo a compress\u00e3o uniforme da junta durante as etapas de aplica\u00e7\u00e3o de torque.<\/figcaption><\/figure>\n\n\n\n<h4 class=\"wp-block-heading\">Insights de especialistas<\/h4>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Nunca pule as etapas 30\/70\/100 \u2014 o aperto em uma \u00fanica passagem \u00e9 a causa mais comum de assentamento irregular da junta<\/li>\n\n\n\n<li>Instala\u00e7\u00f5es em climas frios (&lt;0 \u00b0C) exigem uma verifica\u00e7\u00e3o obrigat\u00f3ria do aperto dos parafusos assim que a temperatura de opera\u00e7\u00e3o for atingida<\/li>\n\n\n\n<li>A &#8220;check pass&#8221; after settling catches relaxation that single measurements miss<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">Erros comuns de instala\u00e7\u00e3o e corre\u00e7\u00f5es no local<\/h2>\n\n\n\n<p>A maioria das falhas em buchas relacionadas ao torque remonta a um dos poucos padr\u00f5es recorrentes, e reconhecer o sintoma precocemente pode impedir que um pequeno erro de instala\u00e7\u00e3o se transforme em uma falha em servi\u00e7o meses depois.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Sinais de falha por torque excessivo<\/h3>\n\n\n\n<p>Over-torquing most commonly shows up as hairline cracking at the porcelain flange seat or, in epoxy bushings, as stress whitening around the mounting holes. In one recurring field pattern, technicians using an impact wrench instead of a calibrated torque wrench for &#8220;speed&#8221; on multi-bushing installations have produced clamping forces 20-30% above target \u2014 often only apparent when the bushing fails a subsequent PD test rather than at the time of installation. Any bushing installed with an uncalibrated tool should be flagged for re-inspection.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Risco de torque insuficiente e descarga parcial<\/h3>\n\n\n\n<p>Under-torqued flanges leave gaps that trap air or moisture at the gasket interface, becoming sites for partial discharge inception once the bushing is energized. A commissioning PD test showing low but non-zero activity at rated voltage on a new installation shouldn&#8217;t be treated as a pass by default \u2014 it often correlates with a torque shortfall on the final pass rather than a manufacturing defect, and is worth cross-checking against the project&#8217;s specified PD acceptance criteria before sign-off.<\/p>\n\n\n\n<p>Em ambos os cen\u00e1rios, a a\u00e7\u00e3o corretiva \u00e9 a mesma: desaperte todos os parafusos em padr\u00e3o de estrela invertida, inspecione a junta quanto a danos vis\u00edveis ou deforma\u00e7\u00e3o permanente, substitua-a se a deforma\u00e7\u00e3o por compress\u00e3o exceder o limite de 10-15% mencionado anteriormente e repita toda a sequ\u00eancia de torque em etapas, em vez de simplesmente aplicar um pouco mais de torque a uma junta j\u00e1 apertada.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"559\" src=\"https:\/\/zeeyielec.com\/wp-content\/uploads\/2026\/07\/zeeyielec-mv-bushing-installation-torque-control-checklist-figure-04.webp-1024x559.webp\" alt=\"Fluxograma de diagn\u00f3stico para falhas na instala\u00e7\u00e3o de buchas de barramento MV relacionadas ao torque\" class=\"wp-image-1913\" srcset=\"https:\/\/zeeyielec.com\/wp-content\/uploads\/2026\/07\/zeeyielec-mv-bushing-installation-torque-control-checklist-figure-04.webp-1024x559.webp 1024w, https:\/\/zeeyielec.com\/wp-content\/uploads\/2026\/07\/zeeyielec-mv-bushing-installation-torque-control-checklist-figure-04.webp-300x164.webp 300w, https:\/\/zeeyielec.com\/wp-content\/uploads\/2026\/07\/zeeyielec-mv-bushing-installation-torque-control-checklist-figure-04.webp-768x419.webp 768w, https:\/\/zeeyielec.com\/wp-content\/uploads\/2026\/07\/zeeyielec-mv-bushing-installation-torque-control-checklist-figure-04.webp-1536x838.webp 1536w, https:\/\/zeeyielec.com\/wp-content\/uploads\/2026\/07\/zeeyielec-mv-bushing-installation-torque-control-checklist-figure-04.webp-2048x1117.webp 2048w, https:\/\/zeeyielec.com\/wp-content\/uploads\/2026\/07\/zeeyielec-mv-bushing-installation-torque-control-checklist-figure-04.webp-18x10.webp 18w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\">Fluxograma que relaciona os padr\u00f5es de sintomas de torque excessivo e insuficiente ao diagn\u00f3stico da causa raiz e \u00e0s medidas corretivas a serem tomadas em campo para buchas de m\u00e9dia tens\u00e3o.<\/figcaption><\/figure>\n\n\n\nFor related failure patterns in bushing well interfaces, see ZeeyiElec&#8217;s <a href=\"https:\/\/zeeyielec.com\/pt\/transformer-accessories\/bushing-well-inserts\/\">inser\u00e7\u00f5es de po\u00e7o de bucha<\/a> p\u00e1gina da s\u00e9rie.\n\n\n\n<h2 class=\"wp-block-heading\">Refer\u00eancias normativas e fontes oficiais<\/h2>\n\n\n\n<p>As pr\u00e1ticas de montagem e torque das buchas de transformadores de m\u00e9dia tens\u00e3o (MV) inserem-se em um contexto mais amplo de normas relativas a acess\u00f3rios de transformadores, proporcionando \u00e0s equipes de instala\u00e7\u00e3o uma base documentada para seus procedimentos, em vez de dependerem exclusivamente de uma tabela do fabricante.<\/p>\n\n\n\n<p>A norma IEEE C57.19.01 regulamenta as caracter\u00edsticas de desempenho e as normas dimensionais para buchas de aparelhos para uso externo, incluindo os requisitos de dist\u00e2ncia de fuga por classe de tens\u00e3o \u2014 as mesmas margens mencionadas anteriormente ao discutir a distor\u00e7\u00e3o da flange causada pelo torque excessivo. A norma IEC 60137 abrange um escopo compar\u00e1vel para buchas utilizadas em sistemas de corrente alternada acima de 1 kV, incluindo os requisitos de testes de rotina e de tipo que uma bucha deve ter sido aprovada antes da instala\u00e7\u00e3o em campo. Quando uma especifica\u00e7\u00e3o de projeto fizer refer\u00eancia a uma norma em detrimento da outra \u2014 o que \u00e9 comum em regi\u00f5es que utilizam normas mistas da IEC e da IEEE, como partes do Oriente M\u00e9dio e da Am\u00e9rica Latina \u2014, as equipes de instala\u00e7\u00e3o devem confirmar qual norma foi utilizada para a fabrica\u00e7\u00e3o e certifica\u00e7\u00e3o da bucha espec\u00edfica, uma vez que as toler\u00e2ncias de torque e de assentamento da junta podem diferir sutilmente entre as duas.<\/p>\n\n\n\n<p>A Brochura T\u00e9cnica 755 do CIGRE, elaborada pelo Grupo de Trabalho A2.43 sobre a confiabilidade das buchas de transformadores, documenta os mecanismos de falha das buchas em servi\u00e7o e sua rela\u00e7\u00e3o com estat\u00edsticas mais amplas de falhas em transformadores, com base em dados de pesquisas internacionais, refor\u00e7ando por que o controle de torque merece o mesmo rigor procedural que os testes el\u00e9tricos durante o comissionamento.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Verifica\u00e7\u00e3o p\u00f3s-instala\u00e7\u00e3o e coloca\u00e7\u00e3o em opera\u00e7\u00e3o<\/h2>\n\n\n\n<p>Torque control doesn&#8217;t end when the wrench is put down on an MV bushing installation \u2014 a proper commissioning sequence confirms the installation will hold up under thermal cycling and load, not just at the moment of assembly.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Nova verifica\u00e7\u00e3o visual e nova verifica\u00e7\u00e3o do torque<\/h3>\n\n\n\n<p>Ap\u00f3s a \u00faltima etapa de aplica\u00e7\u00e3o de torque, uma verifica\u00e7\u00e3o pontual documentada com uma chave de torque calibrada em pelo menos 25% de parafusos (alternando quais parafusos s\u00e3o verificados entre as visitas de comissionamento) ajuda a identificar qualquer junta que tenha se afrouxado ap\u00f3s o aperto inicial. Isso geralmente \u00e9 repetido assim que o transformador atinge a temperatura normal de opera\u00e7\u00e3o, uma vez que a expans\u00e3o t\u00e9rmica pode alterar a for\u00e7a de fixa\u00e7\u00e3o em rela\u00e7\u00e3o ao estado frio no momento da instala\u00e7\u00e3o.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Resist\u00eancia de isolamento \/ Testes de descarga parcial<\/h3>\n\n\n\n<p>Insulation resistance testing, generally at 5 kV to 10 kV DC depending on bushing class, along with a partial discharge check, should be run before energization to confirm the sealing interface achieved earlier didn&#8217;t leave measurable moisture or air gaps at the flange.<\/p>\n\n\n\nGetting torque values right the first time starts with using bushings and gaskets sized correctly for the application. ZeeyiElec&#8217;s <a href=\"https:\/\/zeeyielec.com\/pt\/transformer-accessories\/medium-voltage-bushings\/\">buchas de m\u00e9dia tens\u00e3o<\/a> come with manufacturer-specific torque charts included in the technical documentation, and the team can help match flange dimensions and gasket specifications to your existing transformer turret before installation day. For full product specs and RFQ support, visit ZeeyiElec&#8217;s <a href=\"https:\/\/zeeyielec.com\/pt\/transformer-accessories\/\">acess\u00f3rios para transformadores<\/a> p\u00e1gina.\n\n\n\n<h2 class=\"wp-block-heading\">Perguntas frequentes<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">Qual torque deve ser aplicado a um parafuso de fixa\u00e7\u00e3o de uma bucha de MV?<\/h3>\n\n\n\n<p>Os valores de torque geralmente variam de moderados a altos, dependendo do di\u00e2metro do parafuso e da classe da bucha, e devem sempre seguir a tabela especificada pelo fabricante original (OEM), em vez de um valor gen\u00e9rico, uma vez que o projeto da flange varia de acordo com o fabricante.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">O torque excessivo pode danificar uma bucha?<\/h3>\n\n\n\n<p>Sim \u2014 um torque excessivo pode rachar carca\u00e7as de porcelana ou deformar interfaces de ep\u00f3xi, especialmente em condi\u00e7\u00f5es ambientais mais frias, quando os materiais apresentam menor elasticidade.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Como saber se uma junta de bucha est\u00e1 corretamente encaixada?<\/h3>\n\n\n\n<p>Uma junta corretamente assentada apresenta compress\u00e3o uniforme em toda a circunfer\u00eancia, sem folgas vis\u00edveis; no entanto, a confirma\u00e7\u00e3o final geralmente requer uma nova verifica\u00e7\u00e3o do torque ap\u00f3s o assentamento inicial.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">O que causa descargas parciais ap\u00f3s a instala\u00e7\u00e3o do buch\u00e3o?<\/h3>\n\n\n\n<p>Parafusos com torque insuficiente ou superf\u00edcies de veda\u00e7\u00e3o contaminadas s\u00e3o causas comuns, uma vez que a compress\u00e3o incompleta da junta pode deixar espa\u00e7os de ar microsc\u00f3picos que se ionizam sob tens\u00e3o el\u00e9trica.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">As buchas devem ser apertadas em padr\u00e3o de estrela?<\/h3>\n\n\n\n<p>Sim, um padr\u00e3o em forma de estrela ou cruz \u00e9 a pr\u00e1tica padr\u00e3o para a maioria das buchas com flange, a fim de garantir uma compress\u00e3o uniforme da junta, embora a sequ\u00eancia exata dependa do n\u00famero de parafusos e da geometria da flange.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Quanto tempo ap\u00f3s a instala\u00e7\u00e3o o torque deve ser verificado novamente?<\/h3>\n\n\n\n<p>Muitos t\u00e9cnicos de campo verificam novamente o torque ap\u00f3s um breve per\u00edodo de estabiliza\u00e7\u00e3o, logo ap\u00f3s a energiza\u00e7\u00e3o inicial, j\u00e1 que os materiais das juntas podem sofrer um leve relaxamento devido aos ciclos t\u00e9rmicos.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">A temperatura ambiente afeta a aplica\u00e7\u00e3o do torque nas buchas?<\/h3>\n\n\n\n<p>Sim \u2014 o frio pode tornar as juntas mais r\u00edgidas e a porcelana mais fr\u00e1gil; portanto, o torque deve, em geral, ser aplicado com mais cautela e verificado novamente assim que as temperaturas se estabilizarem.<\/p>","protected":false},"excerpt":{"rendered":"<p>This MV bushing installation torque control checklist walks through the sealing interface, torque staging, and diagnostic steps that determine whether a medium-voltage bushing holds up under thermal cycling and electrical stress over decades of service. Torque control is not a formality in MV bushing installation \u2014 it&#8217;s the mechanism that determines whether the sealing interface [&hellip;]<\/p>\n","protected":false},"author":3,"featured_media":1909,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[6,3],"tags":[],"class_list":["post-1908","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-transformer-accessories-knowledge","category-useful"],"blocksy_meta":[],"_links":{"self":[{"href":"https:\/\/zeeyielec.com\/pt\/wp-json\/wp\/v2\/posts\/1908","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/zeeyielec.com\/pt\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/zeeyielec.com\/pt\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/zeeyielec.com\/pt\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/zeeyielec.com\/pt\/wp-json\/wp\/v2\/comments?post=1908"}],"version-history":[{"count":1,"href":"https:\/\/zeeyielec.com\/pt\/wp-json\/wp\/v2\/posts\/1908\/revisions"}],"predecessor-version":[{"id":1914,"href":"https:\/\/zeeyielec.com\/pt\/wp-json\/wp\/v2\/posts\/1908\/revisions\/1914"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/zeeyielec.com\/pt\/wp-json\/wp\/v2\/media\/1909"}],"wp:attachment":[{"href":"https:\/\/zeeyielec.com\/pt\/wp-json\/wp\/v2\/media?parent=1908"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/zeeyielec.com\/pt\/wp-json\/wp\/v2\/categories?post=1908"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/zeeyielec.com\/pt\/wp-json\/wp\/v2\/tags?post=1908"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}