{"id":2209,"date":"2026-10-08T22:36:04","date_gmt":"2026-10-08T14:36:04","guid":{"rendered":"https:\/\/jutrion.com\/?p=2209"},"modified":"2026-10-08T22:36:07","modified_gmt":"2026-10-08T14:36:07","slug":"275v-vs-320v-vs-385v-spd-choose-correct-uc","status":"publish","type":"post","link":"https:\/\/jutrion.com\/pt\/275v-vs-320v-vs-385v-spd-choose-correct-uc\/","title":{"rendered":"275 V vs 320 V vs 385 V SPD: Como Escolher o Uc Correto"},"content":{"rendered":"<h2 class=\"wp-block-heading has-palette-color-9-color has-text-color has-link-color has-large-font-size wp-elements-1\">275 V, 320 V ou 385 V: A Resposta Curta<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Para uma instala\u00e7\u00e3o de 230\/400 V AC, um SPD de 275 V \u00e9 frequentemente o primeiro candidato quando seu modo de prote\u00e7\u00e3o normalmente v\u00ea cerca de 230 V, mas n\u00e3o \u00e9 uma escolha autom\u00e1tica para toda rede. Use 320 V quando o projeto aprovado precisar de mais margem de tens\u00e3o cont\u00ednua ou sobretens\u00e3o tempor\u00e1ria, e use 385 V apenas quando o modo de prote\u00e7\u00e3o real, arranjo de aterramento e dados do fabricante justificarem essa classifica\u00e7\u00e3o mais alta. N\u00e3o selecione apenas com base na tens\u00e3o nominal do sistema.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">O correto U<sub>c<\/sub> \u00e9 a m\u00e1xima tens\u00e3o cont\u00ednua de opera\u00e7\u00e3o aprovada que permanece acima da maior tens\u00e3o que o SPD pode experimentar continuamente em seu modo conectado. Tamb\u00e9m deve suportar as condi\u00e7\u00f5es de sobretens\u00e3o tempor\u00e1ria esperadas naquele ponto. Ap\u00f3s selecionar U<sub>c<\/sub>, verifique se o n\u00edvel de prote\u00e7\u00e3o de tens\u00e3o resultante U<sub>p<\/sub> ainda \u00e9 baixo o suficiente para o equipamento protegido.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Essa \u00faltima verifica\u00e7\u00e3o \u00e9 importante porque U<sub>c<\/sub> n\u00e3o \u00e9 uma classifica\u00e7\u00e3o de corrente de surto. Um cartucho de 385 V n\u00e3o \u00e9 uma vers\u00e3o mais forte de um cartucho de 275 V em todos os aspectos. Pode tolerar uma tens\u00e3o de frequ\u00eancia de pot\u00eancia sustentada mais alta, mas pode come\u00e7ar a limitar em uma tens\u00e3o mais alta e pode ter um U<sub>p<\/sub>. declarado mais alto. Portanto, a melhor escolha equilibra a estabilidade do servi\u00e7o com o n\u00edvel de prote\u00e7\u00e3o.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"341\" src=\"https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/01-spd-uc-275v-320v-385v-comparison-1024x341.webp\" alt=\"\" class=\"wp-image-2231\" srcset=\"https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/01-spd-uc-275v-320v-385v-comparison-1024x341.webp 1024w, https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/01-spd-uc-275v-320v-385v-comparison-300x100.webp 300w, https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/01-spd-uc-275v-320v-385v-comparison-768x256.webp 768w, https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/01-spd-uc-275v-320v-385v-comparison-18x6.webp 18w, https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/01-spd-uc-275v-320v-385v-comparison.webp 1200w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\"><code><em>Compara\u00e7\u00e3o das classifica\u00e7\u00f5es Uc de SPD de 275 V, 320 V e 385 V em um circuito de 230 V fase-a-neutro.<\/em><\/code><\/figcaption><\/figure>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<h2 class=\"wp-block-heading has-palette-color-9-color has-text-color has-link-color has-large-font-size wp-elements-2\">O que U<sub>c<\/sub> realmente significa em um SPD AC<\/h2>\n<\/blockquote>\n\n\n\n<p class=\"wp-block-paragraph\">U<sub>c<\/sub> \u00e9 a m\u00e1xima tens\u00e3o cont\u00ednua de opera\u00e7\u00e3o que pode ser aplicada nos terminais do SPD nas condi\u00e7\u00f5es declaradas pelo fabricante. Em um produto AC, normalmente \u00e9 um valor RMS na frequ\u00eancia declarada. Durante a opera\u00e7\u00e3o normal, o SPD deve permanecer est\u00e1vel nessa tens\u00e3o sem se comportar como se cada pico da rede fosse um surto.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Esta defini\u00e7\u00e3o explica por que U<sub>c<\/sub> deve ser lido em um modo de prote\u00e7\u00e3o espec\u00edfico:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>L\u2013N:<\/strong> fase a neutro;<\/li>\n\n\n\n<li><strong>L\u2013PE:<\/strong> fase a terra de prote\u00e7\u00e3o;<\/li>\n\n\n\n<li><strong>N\u2013PE:<\/strong> neutro a terra de prote\u00e7\u00e3o; ou<\/li>\n\n\n\n<li><strong>L\u2013L:<\/strong> fase a fase em um arranjo projetado para esse modo.<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Uma rede trif\u00e1sica pode ser descrita como 230\/400 V, no entanto, a tens\u00e3o em um m\u00f3dulo SPD individual pode ser 230 V ou 400 V dependendo de onde esse m\u00f3dulo est\u00e1 conectado. Portanto, o r\u00f3tulo do sistema e o r\u00f3tulo do cartucho n\u00e3o s\u00e3o intercambi\u00e1veis.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">N\u00e3o confunda U<sub>c<\/sub> com os outros n\u00fameros impressos em um SPD:<\/p>\n\n\n\n<figure class=\"wp-block-table jutrion-table\"><table class=\"has-fixed-layout\"><thead><tr><th>Marca\u00e7\u00e3o<\/th><th>O que descreve<\/th><th>O que n\u00e3o prova<\/th><\/tr><\/thead><tbody><tr><td>U<sub>c<\/sub><\/td><td>Tens\u00e3o m\u00e1xima que pode permanecer continuamente no modo de prote\u00e7\u00e3o declarado<\/td><td>Capacidade de descarga de surto ou a tens\u00e3o entregue \u00e0 carga durante um surto<\/td><\/tr><tr><td>U<sub>p<\/sub><\/td><td>N\u00edvel de prote\u00e7\u00e3o de tens\u00e3o declarado sob condi\u00e7\u00f5es de teste de impulso especificadas<\/td><td>Toler\u00e2ncia de tens\u00e3o de opera\u00e7\u00e3o cont\u00ednua<\/td><\/tr><tr><td>I<sub>n<\/sub><\/td><td>Dever de corrente de descarga nominal usando a forma de onda 8\/20 \u00b5s<\/td><td>Capacidade de raio direto<\/td><\/tr><tr><td>I<sub>m\u00e1x.<\/sub><\/td><td>Corrente m\u00e1xima de descarga para um SPD Tipo 2 sob o teste de 8\/20 \u00b5s declarado<\/td><td>Dever repetido nesse valor m\u00e1ximo<\/td><\/tr><tr><td>I<sub>imp.<\/sub><\/td><td>Dever de corrente de impulso associado ao teste Tipo 1 e \u00e0 forma de onda 10\/350 \u00b5s<\/td><td>Um substituto para U<sub>c<\/sub> ou U<sub>p<\/sub><\/td><\/tr><tr><td>U<sub>T<\/sub> \/ dados TOV<\/td><td>Comportamento sob uma sobretens\u00e3o tempor\u00e1ria de frequ\u00eancia de pot\u00eancia especificada por uma dura\u00e7\u00e3o declarada<\/td><td>Permiss\u00e3o para operar continuamente nessa tens\u00e3o<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">Para uma explica\u00e7\u00e3o mais ampla sobre tipos de SPD, classifica\u00e7\u00f5es de corrente de descarga e posi\u00e7\u00f5es de instala\u00e7\u00e3o, utilize o <a href=\"https:\/\/jutrion.com\/pt\/surge-protective-device-guide\/\">guia de dispositivos de prote\u00e7\u00e3o contra surtos JUTRION<\/a>. Este artigo se concentra na decis\u00e3o mais restrita: escolher entre 275 V, 320 V e 385 V U<sub>c<\/sub> valores.<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<h2 class=\"wp-block-heading has-palette-color-9-color has-text-color has-link-color has-large-font-size wp-elements-3\">Por que Todas as Tr\u00eas Classifica\u00e7\u00f5es Aparecem em Projetos de 230\/400 V<\/h2>\n<\/blockquote>\n\n\n\n<p class=\"wp-block-paragraph\">As tr\u00eas classifica\u00e7\u00f5es existem porque um sistema de baixa tens\u00e3o n\u00e3o apresenta uma tens\u00e3o perfeitamente fixa sob todas as condi\u00e7\u00f5es de opera\u00e7\u00e3o e falha. A toler\u00e2ncia de fornecimento, a regula\u00e7\u00e3o de tens\u00e3o, a distor\u00e7\u00e3o harm\u00f4nica, o deslocamento do neutro, as falhas \u00e0 terra e o arranjo de aterramento podem alterar a tens\u00e3o aplicada a um modo de prote\u00e7\u00e3o. As fam\u00edlias de produtos tamb\u00e9m diferem em seu comportamento TOV e tecnologia interna.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Para uma alimenta\u00e7\u00e3o nominal de 230 V fase-a-neutro, a raz\u00e3o simples \u00e9:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>275 \/ 230 = 1,20, 320 \/ 230 = 1,39, e 385 \/ 230 = 1,67.<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Essas raz\u00f5es s\u00e3o \u00fateis para ver a margem de tens\u00e3o cont\u00ednua crescente, mas n\u00e3o s\u00e3o uma f\u00f3rmula de sele\u00e7\u00e3o completa. Elas n\u00e3o descrevem a tens\u00e3o m\u00e1xima em regime permanente do local, o modo de prote\u00e7\u00e3o, ou como o SPD se comporta durante um TOV. Dois SPDs com o mesmo U<sub>c<\/sub> tamb\u00e9m podem ter diferentes U<sub>T<\/sub>, U<sub>p<\/sub>, dados de prote\u00e7\u00e3o de backup e desconex\u00e3o.<\/p>\n\n\n\n<figure class=\"wp-block-table jutrion-table\"><table class=\"has-fixed-layout\"><thead><tr><th>U<sub>c<\/sub> classe<\/th><th>Raz\u00e3o t\u00edpica para entrar na lista restrita<\/th><th>Principal benef\u00edcio<\/th><th>Principal verifica\u00e7\u00e3o antes da aprova\u00e7\u00e3o<\/th><\/tr><\/thead><tbody><tr><td>275 V CA<\/td><td>O modo de prote\u00e7\u00e3o normalmente v\u00ea aproximadamente 230 V e os dados de TOV do produto se adequam \u00e0 rede<\/td><td>Margem de tens\u00e3o mais apertada geralmente suporta um n\u00edvel de prote\u00e7\u00e3o relativamente baixo<\/td><td>Pode permanecer est\u00e1vel na maior tens\u00e3o cont\u00ednua do local e sobreviver ao TOV especificado?<\/td><\/tr><tr><td>320 V CA<\/td><td>O projeto precisa de margem de tens\u00e3o operacional adicional, ou o fabricante atribui essa classe \u00e0 configura\u00e7\u00e3o de rede necess\u00e1ria<\/td><td>Mais toler\u00e2ncia \u00e0 eleva\u00e7\u00e3o de tens\u00e3o sustentada do que uma classe de 275 V<\/td><td>Seu U<sub>p<\/sub> ainda est\u00e1 coordenado com a tens\u00e3o de impulso de resist\u00eancia do equipamento?<\/td><\/tr><tr><td>385 V CA<\/td><td>O modo conectado ou a estrat\u00e9gia de TOV aprovada requer substancialmente mais margem de tens\u00e3o<\/td><td>Risco reduzido de opera\u00e7\u00e3o indesejada devido \u00e0 eleva\u00e7\u00e3o da tens\u00e3o de frequ\u00eancia de pot\u00eancia<\/td><td>A classe mais alta deixa um n\u00edvel de prote\u00e7\u00e3o efetivo suficientemente baixo na carga?<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">Esta \u00e9 uma tabela de triagem, n\u00e3o um gr\u00e1fico de substitui\u00e7\u00e3o universal. Um dispositivo de 320 V n\u00e3o pode substituir automaticamente um dispositivo de 275 V, e um dispositivo de 385 V n\u00e3o pode ser aprovado apenas porque \u00e9 menos prov\u00e1vel que reaja a uma tens\u00e3o de rede elevada.<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<h2 class=\"wp-block-heading has-palette-color-9-color has-text-color has-link-color has-large-font-size wp-elements-4\">Comece com a Tens\u00e3o Atrav\u00e9s de Cada Modo de Prote\u00e7\u00e3o<\/h2>\n<\/blockquote>\n\n\n\n<p class=\"wp-block-paragraph\">Desenhe a conex\u00e3o do SPD antes de escolher o cartucho. Marque a tens\u00e3o normal em cada modo e pergunte qual tens\u00e3o pode aparecer ali durante os estados operacionais e de falha cred\u00edveis definidos pelo projeto.<\/p>\n\n\n\n<h3 class=\"wp-block-heading has-palette-color-9-color has-text-color has-link-color has-medium-font-size wp-elements-5\">Prote\u00e7\u00e3o Monof\u00e1sica 230 V, L\u2013N<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Um SPD conectado da linha ao neutro normalmente v\u00ea a tens\u00e3o fase-a-neutro. Em um sistema de 230 V comum e corretamente regulado, 275 V \u00e9 frequentemente listado. A aprova\u00e7\u00e3o ainda depende da faixa de fornecimento permitida, medi\u00e7\u00f5es no local onde relevante, requisitos de TOV e a ficha t\u00e9cnica exata.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Se o local operar regularmente perto ou acima do limite superior assumido pelo projeto, selecionar 275 V apenas pelo r\u00f3tulo nominal pode causar envelhecimento acelerado ou opera\u00e7\u00e3o desnecess\u00e1ria do desconector t\u00e9rmico. A resposta de engenharia n\u00e3o \u00e9 automaticamente \u201cinstalar 385 V.\u201d Primeiro, determine se a tens\u00e3o elevada \u00e9 uma condi\u00e7\u00e3o operacional v\u00e1lida, um problema de qualidade de fornecimento, uma falha no neutro ou uma aplica\u00e7\u00e3o fora do projeto original.<\/p>\n\n\n\n<h3 class=\"wp-block-heading has-palette-color-9-color has-text-color has-link-color has-medium-font-size wp-elements-6\">Prote\u00e7\u00e3o Trif\u00e1sica 230\/400 V, L\u2013N ou L\u2013PE<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Em um sistema estrela 230\/400 V, cada fase est\u00e1 cerca de 230 V em rela\u00e7\u00e3o ao neutro e cerca de 400 V em rela\u00e7\u00e3o a outra fase. Um m\u00f3dulo conectado L\u2013N, portanto, n\u00e3o est\u00e1 continuamente exposto a 400 V durante a opera\u00e7\u00e3o normal. Um m\u00f3dulo conectado em outro modo pode enfrentar um requisito diferente.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Essa distin\u00e7\u00e3o \u00e9 a raz\u00e3o pela qual a contagem de polos n\u00e3o seleciona U<sub>c<\/sub>. \u201cDispositivo de prote\u00e7\u00e3o contra surtos (SPD) de quatro polos para um painel de 400 V\u201d est\u00e1 incompleto. A especifica\u00e7\u00e3o deve indicar a configura\u00e7\u00e3o da rede e o circuito de prote\u00e7\u00e3o, como 3+1 ou 4+0, e identificar a tens\u00e3o em cada m\u00f3dulo.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"341\" src=\"https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/02-three-phase-spd-3-plus-1-protection-modes-1024x341.webp\" alt=\"\" class=\"wp-image-2232\" srcset=\"https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/02-three-phase-spd-3-plus-1-protection-modes-1024x341.webp 1024w, https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/02-three-phase-spd-3-plus-1-protection-modes-300x100.webp 300w, https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/02-three-phase-spd-3-plus-1-protection-modes-768x256.webp 768w, https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/02-three-phase-spd-3-plus-1-protection-modes-18x6.webp 18w, https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/02-three-phase-spd-3-plus-1-protection-modes.webp 1200w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\"><code><em>Arranjo de SPD trif\u00e1sico 3+1 com L1, L2 e L3 protegidos em rela\u00e7\u00e3o ao neutro e um m\u00f3dulo N-PE separado.<\/em><\/code><\/figcaption><\/figure>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<h2 class=\"wp-block-heading has-palette-color-9-color has-text-color has-link-color has-large-font-size wp-elements-7\">Sistema de Aterramento e Arranjo de Circuito Mude a Resposta<\/h2>\n<\/blockquote>\n\n\n\n<p class=\"wp-block-paragraph\">O mesmo fornecimento nominal de 230\/400 V pode exigir uma montagem de SPD diferente dependendo se \u00e9 TN-C, TN-S, TT ou IT. A quest\u00e3o importante n\u00e3o \u00e9 apenas quantos m\u00f3dulos est\u00e3o instalados, mas quais componentes est\u00e3o conectados entre quais condutores.<\/p>\n\n\n\n<h3 class=\"wp-block-heading has-palette-color-9-color has-text-color has-link-color has-medium-font-size wp-elements-8\">Sistemas TN<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Sistemas TN-C e TN-S t\u00eam diferentes pontos de conex\u00e3o PEN ou N\/PE, portanto, use uma montagem declarada para o arranjo TN espec\u00edfico. Um cartucho de 275 V \u00e9 comum para um modo de prote\u00e7\u00e3o de 230 V, mas seu desempenho TOV ainda precisa ser aprovado; variantes de 320 V ou 385 V s\u00e3o usadas apenas onde a margem de tens\u00e3o cont\u00ednua ou TOV exigida as suporta.<\/p>\n\n\n\n<h3 class=\"wp-block-heading has-palette-color-9-color has-text-color has-link-color has-medium-font-size wp-elements-9\">Sistemas TT e Circuitos 3+1<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Um arranjo 3+1 comumente coloca componentes limitadores de tens\u00e3o de fase a neutro e um componente baseado em gap de fa\u00edsca de neutro a PE. Os cartuchos de fase s\u00e3o, portanto, selecionados para servi\u00e7o L\u2013N; o componente N\u2013PE tem dados diferentes. Este arranjo pode controlar as consequ\u00eancias de TOV em sistemas TT, mas deve seguir a norma de instala\u00e7\u00e3o aplic\u00e1vel e as instru\u00e7\u00f5es do fabricante.<\/p>\n\n\n\n<h3 class=\"wp-block-heading has-palette-color-9-color has-text-color has-link-color has-medium-font-size wp-elements-10\">Sistemas IT<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Em um sistema IT, condutores saud\u00e1veis podem subir em rela\u00e7\u00e3o \u00e0 terra ap\u00f3s a primeira falha \u00e0 terra. N\u00e3o especifique um cartucho L\u2013PE de 275 V apenas porque as cargas s\u00e3o chamadas de 230 V. Use uma montagem declarada para o arranjo IT e verifique a tens\u00e3o do condutor em rela\u00e7\u00e3o \u00e0 terra, modos de prote\u00e7\u00e3o e comportamento TOV.<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<h2 class=\"wp-block-heading has-palette-color-9-color has-text-color has-link-color has-large-font-size wp-elements-11\">O Verdadeiro Compromisso: Envelhecimento Indesejado Versus N\u00edvel de Prote\u00e7\u00e3o<\/h2>\n<\/blockquote>\n\n\n\n<p class=\"wp-block-paragraph\">Escolhendo U<sub>c<\/sub> muito baixo e escolhendo-o muito alto criam problemas diferentes.<\/p>\n\n\n\n<h3 class=\"wp-block-heading has-palette-color-9-color has-text-color has-link-color has-medium-font-size wp-elements-12\">Se U<sub>c<\/sub> Estiver Muito Baixo<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Um varistor de \u00f3xido met\u00e1lico \u00e9 dependente da tens\u00e3o. Opera\u00e7\u00e3o repetida ou sustentada muito pr\u00f3xima ao seu limite cont\u00ednuo pode aumentar a fuga, temperatura e envelhecimento. Uma sobretens\u00e3o tempor\u00e1ria fora da capacidade declarada pode fazer o desconector t\u00e9rmico interno operar, deixando o circuito a jusante energizado, mas n\u00e3o mais protegido contra surtos. Em um desajuste severo, a falha pode ser insegura, a menos que o produto e a prote\u00e7\u00e3o de backup a limpem corretamente.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Um indicador vermelho logo ap\u00f3s a comissionamento n\u00e3o prova necessariamente que o local experimentou um evento excepcional de raios. A investiga\u00e7\u00e3o deve incluir tens\u00e3o em estado estacion\u00e1rio, integridade do neutro, fia\u00e7\u00e3o, exposi\u00e7\u00e3o a TOV, prote\u00e7\u00e3o de backup e se o U instalado<sub>c<\/sub> e o circuito correspondem \u00e0 rede.<\/p>\n\n\n\n<h3 class=\"wp-block-heading has-palette-color-9-color has-text-color has-link-color has-medium-font-size wp-elements-13\">Se U<sub>c<\/sub> Est\u00e1 Muito Alto<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">A higher-U<sub>c<\/sub> varistor normally begins significant conduction at a higher voltage. Depending on the product design, this can raise U<sub>p<\/sub>. For example, one manufacturer\u2019s otherwise comparable single-pole Type 2 family declares U<sub>p<\/sub> at no more than 1.5 kV for its 275 V and 320 V versions, but no more than 1.75 kV for its 385 V version. That is a product example, not a universal conversion rule, but it shows why the higher number is not automatically superior.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The relevant protection at the load is not just the catalogue U<sub>p<\/sub>. Connection-lead inductance adds voltage while surge current rises. Long conductors can erase the apparent advantage of a lower U<sub>p<\/sub>. U<sub>c<\/sub>, U<sub>p<\/sub>, conductor length and equipment impulse withstand voltage must therefore be coordinated together.<\/p>\n\n\n\n<blockquote class=\"wp-block-quote jutrion-info-box is-layout-flow wp-block-quote-is-layout-flow\">\n<p class=\"wp-block-paragraph\"><strong>Selection principle:<\/strong> choose the lowest U<sub>c<\/sub> class that is approved for the maximum continuous voltage, protection mode, earthing arrangement and TOV duty. Then confirm that its U<sub>p<\/sub> and installed lead voltage remain below the protected equipment\u2019s impulse withstand requirement with an adequate margin.<\/p>\n<\/blockquote>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"341\" src=\"https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/03-spd-uc-tov-up-selection-tradeoff-1024x341.webp\" alt=\"\" class=\"wp-image-2235\" srcset=\"https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/03-spd-uc-tov-up-selection-tradeoff-1024x341.webp 1024w, https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/03-spd-uc-tov-up-selection-tradeoff-300x100.webp 300w, https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/03-spd-uc-tov-up-selection-tradeoff-768x256.webp 768w, https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/03-spd-uc-tov-up-selection-tradeoff-18x6.webp 18w, https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/03-spd-uc-tov-up-selection-tradeoff.webp 1200w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\"><code><em>SPD Uc selection trade-off between low-voltage ageing and a higher downstream voltage protection level.<\/em><\/code><\/figcaption><\/figure>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<h2 class=\"wp-block-heading has-palette-color-9-color has-text-color has-link-color has-large-font-size wp-elements-14\">Field Case: Why Moving Straight to 385 V Left the VFDs Exposed<\/h2>\n<\/blockquote>\n\n\n\n<p class=\"wp-block-paragraph\">An anonymized cold-chain packaging facility in Southeast Asia experienced repeated SPD disconnector operation on secondary 230\/400 V distribution panels during the first three months after commissioning. The indicators on several installed 275 V Type 2 cartridges changed to red. The local contractor assumed that frequent lightning surges were exhausting the SPDs and replaced the cartridges with 385 V versions, treating the higher U<sub>c<\/sub> as a heavier-duty rating.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Two months later, a grid-switching event was followed by dielectric failure in three variable frequency drives and two digital controller cards. The 385 V cartridges remained serviceable, forcing the investigation to separate the original nuisance disconnection from the later failure of protection coordination.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"341\" src=\"https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/04-385v-spd-vfd-field-case-1024x341.webp\" alt=\"\" class=\"wp-image-2233\" srcset=\"https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/04-385v-spd-vfd-field-case-1024x341.webp 1024w, https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/04-385v-spd-vfd-field-case-300x100.webp 300w, https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/04-385v-spd-vfd-field-case-768x256.webp 768w, https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/04-385v-spd-vfd-field-case-18x6.webp 18w, https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/04-385v-spd-vfd-field-case.webp 1200w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\"><code><em>Field case showing a 385 V SPD, 60 cm connection path and approximately 2.4 kV reaching downstream VFDs.<\/em><\/code><\/figcaption><\/figure>\n\n\n\n<h3 class=\"wp-block-heading has-palette-color-9-color has-text-color has-link-color has-medium-font-size wp-elements-15\">Why the 275 V Cartridges Were Disconnecting<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Recorded phase-to-neutral voltage repeatedly reached 258\u2013262 V AC RMS and contained notable fifth-harmonic distortion. The investigation attributed rising varistor leakage and temperature to prolonged power-frequency stress rather than repeated lightning impulses. This does not mean every 275 V SPD will fail at 262 V: the response also depends on TOV data, waveform, ambient temperature and ageing. Here, the site measurements and product data had not been reviewed together.<\/p>\n\n\n\n<h3 class=\"wp-block-heading has-palette-color-9-color has-text-color has-link-color has-medium-font-size wp-elements-16\">Why the 385 V Replacement Was Not an Equivalent Upgrade<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">The 385 V cartridges tolerated the elevated supply, but their declared U<sub>p<\/sub> was 1.8 kV versus no more than 1.35 kV for the original cartridges. The 60 cm connection path was estimated, for the assessed surge current and geometry, to add about 0.6 kV. The resulting 2.4 kV first-pass estimate did not exceed the drives\u2019 stated 2.5 kV impulse withstand, but it left almost no margin for tolerance, waveform and installation effects.<\/p>\n\n\n\n<h3 class=\"wp-block-heading has-palette-color-9-color has-text-color has-link-color has-medium-font-size wp-elements-17\">Resolution: Use the Middle Voltage Class and Shorten the Current Path<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">The replacement used a JUTRION 320 V Type 2 configuration declared at U<sub>p<\/sub> \u2264 1.4 kV. Its U<sub>c<\/sub> provided approximately 22% margin over the recorded 262 V RMS, subject to confirmation against the product documentation and site TOV assessment. Busbar comb connections and optimized V-wiring reduced the total path from about 60 cm to less than 25 cm; under the same estimation method, inductive addition fell below approximately 0.25 kV and the effective protection estimate stayed below about 1.65 kV.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">No repeat nuisance disconnection or related controller damage was reported during the observation period. The correction combined sufficient continuous-voltage margin, a lower U<sub>p<\/sub> and a shorter discharge path instead of automatically selecting the highest U<sub>c<\/sub>.<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<h2 class=\"wp-block-heading has-palette-color-9-color has-text-color has-link-color has-large-font-size wp-elements-18\">A Worked 230\/400 V Panel Comparison<\/h2>\n<\/blockquote>\n\n\n\n<p class=\"wp-block-paragraph\">For an illustrative 230\/400 V commercial board with separate N and PE conductors and a 3+1 SPD, review the candidates in this order:<\/p>\n\n\n\n<ol class=\"wp-block-list\">\n<li><strong>Identify the mode voltage.<\/strong> Each phase module is connected L\u2013N, so it normally sees about 230 V, not 400 V.<\/li>\n\n\n\n<li><strong>Establish the highest continuous supply voltage.<\/strong> Use the project\u2019s supply tolerance and any verified site data. Do not treat an abnormal neutral condition as an ordinary continuous operating point.<\/li>\n\n\n\n<li><strong>Define TOV duty.<\/strong> Review the earthing system, plausible neutral and earth faults, and the U<sub>T<\/sub>-versus-time data required by the installation design.<\/li>\n\n\n\n<li><strong>Compare approved products.<\/strong> A 275 V version may provide adequate continuous and TOV performance. If it does not, the 320 V version may be evaluated. A 385 V version remains a candidate only if the higher margin is actually necessary.<\/li>\n\n\n\n<li><strong>Recheck protection performance.<\/strong> Compare U<sub>p<\/sub> for each exact model, then include the effect of the connecting conductors and coordination with downstream protection.<\/li>\n<\/ol>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"341\" src=\"https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/05-spd-lead-length-v-wiring-comparison-1024x341.webp\" alt=\"\" class=\"wp-image-2234\" srcset=\"https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/05-spd-lead-length-v-wiring-comparison-1024x341.webp 1024w, https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/05-spd-lead-length-v-wiring-comparison-300x100.webp 300w, https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/05-spd-lead-length-v-wiring-comparison-768x256.webp 768w, https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/05-spd-lead-length-v-wiring-comparison-18x6.webp 18w, https:\/\/jutrion.com\/wp-content\/uploads\/2026\/10\/05-spd-lead-length-v-wiring-comparison.webp 1200w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><figcaption class=\"wp-element-caption\"><code><em>Comparison of a 60 cm SPD connection and optimized V-wiring under 25 cm for improved VFD protection.<\/em><\/code><\/figcaption><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">If 275 V passes the continuous-voltage and TOV checks, it normally remains the first candidate. Move to 320 V when additional margin is required and U<sub>p<\/sub> remains acceptable. Use 385 V only when the mode or TOV duty justifies it and the downstream protection calculation still passes.<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<h2 class=\"wp-block-heading has-palette-color-9-color has-text-color has-link-color has-large-font-size wp-elements-19\">Read U<sub>c<\/sub>, U<sub>T<\/sub> and U<sub>p<\/sub> as One Set<\/h2>\n<\/blockquote>\n\n\n\n<p class=\"wp-block-paragraph\">An SPD datasheet should allow the designer to trace three different voltage questions:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>U<sub>c<\/sub>:<\/strong> What voltage may remain continuously across this protection mode?<\/li>\n\n\n\n<li><strong>U<sub>T<\/sub> or TOV characteristic:<\/strong> What happens at a stated power-frequency overvoltage and duration\u2014does the SPD withstand it or fail safely?<\/li>\n\n\n\n<li><strong>U<sub>p<\/sub>:<\/strong> To what declared level does the SPD limit a specified impulse at its terminals?<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Do not infer one value from another. After voltage compatibility is established, separately verify Type 1, Type 2 or Type 1+2 duty; I<sub>imp.<\/sub>, I<sub>n<\/sub> e I<sub>m\u00e1x.<\/sub>; prospective short-circuit current; disconnection; backup protection; and remote indication.<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<h2 class=\"wp-block-heading has-palette-color-9-color has-text-color has-link-color has-large-font-size wp-elements-20\">What to Put in an SPD Enquiry or Specification<\/h2>\n<\/blockquote>\n\n\n\n<p class=\"wp-block-paragraph\">\u201cNeed 4P 385 V SPD\u201d is not enough information for a reliable product match. Send the electrical context that determines the cartridge duty:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>nominal system voltage and frequency;<\/li>\n\n\n\n<li>single-phase or three-phase conductor arrangement;<\/li>\n\n\n\n<li>earthing system: TN-C, TN-S, TT, IT or another defined arrangement;<\/li>\n\n\n\n<li>required protection circuit, such as 1+1, 3+1 or 4+0;<\/li>\n\n\n\n<li>SPD type and installation position;<\/li>\n\n\n\n<li>required U<sub>c<\/sub>, TOV and U<sub>p<\/sub> performance;<\/li>\n\n\n\n<li>I<sub>imp.<\/sub>, I<sub>n<\/sub> e I<sub>m\u00e1x.<\/sub> requirements;<\/li>\n\n\n\n<li>prospective short-circuit current and upstream protection;<\/li>\n\n\n\n<li>remote contact, replaceable module and certification requirements; and<\/li>\n\n\n\n<li>destination market, quantity and project documentation needs.<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">A <a href=\"https:\/\/jutrion.com\/pt\/spd\/\">JUTRION AC SPD range<\/a> includes Type 2 and Type 1+2 options for low-voltage distribution systems. A final model should be matched to the actual network and connection diagram rather than selected from the U<sub>c<\/sub> number in isolation.<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<h2 class=\"wp-block-heading has-palette-color-9-color has-text-color has-link-color has-large-font-size wp-elements-21\">Common Questions About 275 V, 320 V and 385 V SPDs<\/h2>\n<\/blockquote>\n\n\n<div id=\"rank-math-faq\" class=\"rank-math-block\">\n<div class=\"rank-math-list\">\n<div id=\"faq-question-1791463372687\" class=\"rank-math-list-item\">\n<h3 class=\"rank-math-question\">Can I use a 385 V SPD on a 230 V system?<\/h3>\n<div class=\"rank-math-answer\">\n\n<p>Possibly, but it is not automatically the best choice. Confirm that the product is declared for the network and protection mode, then compare its U<sub>p<\/sub> with the protected equipment. The extra U<sub>c<\/sub> margin is useful only if the design needs it and the resulting protection level remains acceptable.<\/p>\n\n<\/div>\n<\/div>\n<div id=\"faq-question-1791464255661\" class=\"rank-math-list-item\">\n<h3 class=\"rank-math-question\">Is a 275 V SPD always correct for a 230 V supply?<\/h3>\n<div class=\"rank-math-answer\">\n\n<p>No. It is a common candidate for a mode that normally sees 230 V, but suitability depends on maximum continuous voltage, earthing system, TOV exposure, circuit arrangement and the exact datasheet.<\/p>\n\n<\/div>\n<\/div>\n<div id=\"faq-question-1791464321354\" class=\"rank-math-list-item\">\n<h3 class=\"rank-math-question\">Why would an SPD fail when no lightning strike was reported?<\/h3>\n<div class=\"rank-math-answer\">\n\n<p>Possible causes include repeated switching surges, sustained overvoltage, a lost or unstable neutral, incorrect U<sub>c<\/sub>, wrong protection circuit, ageing, loose connections or inadequate backup coordination. A failed indicator is a reason to investigate the system, not merely to fit a higher-voltage cartridge.<\/p>\n\n<\/div>\n<\/div>\n<div id=\"faq-question-1791464332925\" class=\"rank-math-list-item\">\n<h3 class=\"rank-math-question\">Does 320 V U<sub>c<\/sub> mean a 320 V nominal system?<\/h3>\n<div class=\"rank-math-answer\">\n\n<p>No. U<sub>c<\/sub> is the maximum continuous voltage across the SPD protection mode, not necessarily the nominal line-to-line or line-to-neutral system designation. Read it with the connection diagram.<\/p>\n\n<\/div>\n<\/div>\n<div id=\"faq-question-1791464348648\" class=\"rank-math-list-item\">\n<h3 class=\"rank-math-question\">Are U<sub>c<\/sub> and U<sub>CPV<\/sub> interchangeable?<\/h3>\n<div class=\"rank-math-answer\">\n\n<p>No. U<sub>CPV<\/sub> is used for photovoltaic DC SPD applications and must be selected from the maximum PV string voltage under the project\u2019s temperature conditions. For that task, use the separate <a href=\"https:\/\/jutrion.com\/pt\/how-to-select-dc-spd-solar-pv\/\">DC SPD selection guide for solar PV<\/a>.<\/p>\n\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<h2 class=\"wp-block-heading has-palette-color-9-color has-text-color has-link-color has-large-font-size wp-elements-22\">The Practical Selection Rule<\/h2>\n<\/blockquote>\n\n\n\n<p class=\"wp-block-paragraph\">Do not choose 275 V, 320 V or 385 V from the front label of the distribution board. First establish the voltage across each SPD protection mode, then verify the highest continuous voltage, earthing arrangement and TOV duty. From the ratings that pass those checks, choose the option that still gives adequate U<sub>p<\/sub> coordination at the protected equipment.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">In many ordinary 230 V protection modes, that process begins with 275 V. It moves to 320 V or 385 V only when the network conditions and manufacturer data support the change. Higher U<sub>c<\/sub> is additional voltage margin\u2014not a universal measure of better surge protection.<\/p>\n\n\n\n<h3 class=\"wp-block-heading has-palette-color-9-color has-text-color has-link-color has-medium-font-size wp-elements-23\">Refer\u00eancias T\u00e9cnicas<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><a href=\"https:\/\/webstore.iec.ch\/en\/publication\/65314\" target=\"_blank\" rel=\"noopener\">IEC 61643-11:2025 \u2014 Low-voltage surge protective devices connected to AC low-voltage power systems<\/a><\/li>\n\n\n\n<li><a href=\"https:\/\/webstore.iec.ch\/en\/publication\/32531\" target=\"_blank\" rel=\"noopener\">IEC 61643-12:2020 \u2014 Selection and application principles for low-voltage SPDs<\/a><\/li>\n\n\n\n<li><a href=\"https:\/\/www.se.com\/ar\/es\/faqs\/FAQ000246782\/\" target=\"_blank\" rel=\"noopener\">Schneider Electric \u2014 IEC SPD parameters including U<sub>c<\/sub>, U<sub>p<\/sub> e I<sub>n<\/sub><\/a><\/li>\n<\/ul>","protected":false},"excerpt":{"rendered":"<p>275 V, 320 V or 385 V: The Short Answer For a 230\/400 V AC installation, a 275 V SPD is often the first candidate when its protection mode normally sees about 230 V, but it is not an automatic choice for every network. Use 320 V when the approved design needs more continuous-voltage or [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":2236,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-2209","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-electrical-guides"],"blocksy_meta":[],"_links":{"self":[{"href":"https:\/\/jutrion.com\/pt\/wp-json\/wp\/v2\/posts\/2209","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/jutrion.com\/pt\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/jutrion.com\/pt\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/jutrion.com\/pt\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/jutrion.com\/pt\/wp-json\/wp\/v2\/comments?post=2209"}],"version-history":[{"count":1,"href":"https:\/\/jutrion.com\/pt\/wp-json\/wp\/v2\/posts\/2209\/revisions"}],"predecessor-version":[{"id":2237,"href":"https:\/\/jutrion.com\/pt\/wp-json\/wp\/v2\/posts\/2209\/revisions\/2237"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/jutrion.com\/pt\/wp-json\/wp\/v2\/media\/2236"}],"wp:attachment":[{"href":"https:\/\/jutrion.com\/pt\/wp-json\/wp\/v2\/media?parent=2209"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/jutrion.com\/pt\/wp-json\/wp\/v2\/categories?post=2209"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/jutrion.com\/pt\/wp-json\/wp\/v2\/tags?post=2209"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}