Não tem certeza se deve pedir um SPD 3P+N ou um SPD 4P para um quadro de distribuição trifásico?
Esta é uma pergunta comum para montadores de painéis, distribuidores elétricos, compradores de OEM e engenheiros de projetos. Os dois produtos podem parecer semelhantes por fora. Ambos podem ter quatro módulos. Ambos podem ser usados em sistemas trifásicos com neutro.
Mas internamente, eles podem usar estruturas de proteção diferentes. A principal diferença não está apenas no número de polos. A principal diferença geralmente é o caminho de proteção entre neutro e terra, também chamado de proteção N-PE.
Índice
Resposta Rápida: Qual é a Diferença Entre SPD 3P+N e SPD 4P?
A SPD 4P geralmente se refere a uma estrutura 4+0.. Neste design, os caminhos de proteção L1-PE, L2-PE, L3-PE e N-PE são comumente caminhos limitadores de tensão, frequentemente baseados em MOV.
A SPD 3P+N geralmente se refere a uma estrutura 3+1.. Neste design, L1-N, L2-N e L3-N usam caminhos de proteção MOV, enquanto o caminho N-PE frequentemente utiliza um componente de comutação de tensão, como um GDT ou gap de centelha..
| Item | SPD 3P+N | SPD 4P |
|---|---|---|
| Estrutura comum | 3+1 | 4+0 |
| proteção de fase | Caminhos MOV L1-N, L2-N, L3-N | Caminhos de limitação de tensão L1-PE, L2-PE, L3-PE |
| proteção N-PE | Geralmente GDT / gap de faísca | Geralmente baseado em MOV, dependendo do projeto |
| Uso comum | TT, TN-S, TN-C-S após a divisão do PEN | TN-S ou projetos específicos do projeto |
| Aviso ao comprador | Confirme o tipo de módulo N-PE | Confirme o diagrama de fiação interno |
Regra simples: não escolha apenas pelas palavras “3P+N” ou “4P” no nome do produto. Sempre verifique o sistema de aterramento e o diagrama de fiação do fabricante.
O que Significa SPD 3P+N?
A SPD 3P+N is commonly used for three-phase power systems with neutral.
It is also called a 3PN SPD, 3+1 SPD, three-phase SPD with neutral, or SPD with N-PE protection.
In a typical 3+1 design, the SPD protects:
- L1 to N
- L2 to N
- L3 to N
- N to PE
The phase paths are usually protected by voltage-limiting components such as MOVs. The N-PE path is often protected by a voltage-switching component such as a GDT or spark gap.
This design is important because the neutral conductor can rise in potential during surge or fault conditions. The N-PE module helps discharge this overvoltage to earth during surge events.
O que Significa SPD 4P?
A SPD 4P means four-pole surge protective device.
In many product ranges, a 4P SPD refers to a estrutura 4+0.. It uses four voltage-limiting protection paths, commonly MOV-based.
A 4P SPD may protect four conductors in a three-phase system with neutral. But the name alone is not enough.
Different manufacturers may use “4P” differently. Some suppliers use 4P for a 4+0 structure. Some buyers use 4P to mean any four-module SPD. In some markets, a 3P+N product may also be called a four-pole SPD because it has four physical modules.
Buyer note: before ordering, check the internal circuit diagram. This is more reliable than the pole name.
3P+N vs 4P SPD: Comparação Principal
| Ponto de Seleção | SPD 3P+N | SPD 4P |
|---|---|---|
| Also called | 3PN SPD, 3+1 SPD | 4-pole SPD, 4+0 SPD |
| Internal concept | Three phase-to-neutral paths plus one N-PE path | Four voltage-limiting protection paths |
| proteção N-PE | Usually voltage-switching | Usually voltage-limiting, depending on design |
| Typical N-PE component | GDT ou gap de centelha. | MOV, depending on the manufacturer design |
| Common grounding systems | TT, TN-S, TN-C-S após a divisão do PEN | TN-S or project-specific systems |
| Best for | Systems where neutral-to-earth protection matters | Systems where the drawing requires 4+0 protection |
| Main risk if selected wrongly | Wrong N-PE protection design | Wrong earthing connection or unsuitable internal structure |
| Buyer should confirm | N-PE module type | Circuit diagram and application system |
Por que o Caminho de Proteção N-PE é Importante
The most important difference is the N-PE path.
In a three-phase system with neutral, surge voltage may appear not only between phase and neutral. It may also appear between neutral and protective earth.
This is especially important in TT systems and some TN-S or TN-C-S installations.
A 3P+N SPD normally uses a special N-PE module. This module is often a spark gap or GDT. It stays insulated during normal operation and conducts during surge events.
This helps reduce leakage current during normal operation. It also helps handle neutral-to-earth overvoltage during surge conditions.
A 4P SPD may use MOV-based protection on all four paths. This can be suitable for some systems, but it is not automatically better.
The real question is simple:
What does your system need between N and PE?
O SPD 3P+N é o Mesmo que o SPD 4P?
No, not always.
They may look similar. Both may have four modules. Both may be installed in a three-phase distribution board with neutral.
But electrically, they can be different.
A SPD 3P+N usually means a 3+1 circuit. A SPD 4P usually means a 4+0 circuit.
The difference is the fourth protection path.
In a 3P+N SPD, the fourth path is usually N-PE protection with a switching component. In a 4P SPD, the fourth path is usually another voltage-limiting protection path.
Do not ask only: “Do you have 4P SPD?”
Ask instead: “Is this a 4+0 SPD, or is it a 3P+N / 3+1 SPD with N-PE spark gap protection?”
Qual SPD Deve Ser Usado em Sistemas TT?
For many three-phase TT systems, a 3P+N SPD / 3+1 SPD is commonly preferred.
In TT systems, neutral and protective earth are separate. The N-PE path can become important during surge events.
A 3+1 design gives specific surge protection between neutral and earth.
For a 230/400V TT distribution board, buyers often ask for:
- Type 2 3P+N SPD
- Type 1+2 3P+N SPD
- 275V, 320V, or 385V Uc depending on system voltage and grid condition
- Remote signal contact if required
- DIN rail mounting
- IEC 61643-11 compliance
For TT systems, do not choose a 4P SPD only because it has four modules. Confirm whether the design is suitable for TT use and whether the N-PE path is correct.
Qual SPD Deve Ser Usado em Sistemas TN-S?
In TN-S systems, neutral and PE are separate conductors.
Both 3P+N and 4P configurations may appear in the market. The correct choice depends on the project design, local practice, and SPD circuit diagram.
For many buyers, a 3P+N SPD is a common choice when the board has L1, L2, L3, N, and PE.
But a 4P SPD may also be specified in some TN-S distribution boards.
The important point is this:
TN-S does not automatically mean 4P. TN-S also does not automatically mean 3P+N.
You need to confirm whether the project requires a 3+1 or 4+0 structure.
Qual SPD Deve Ser Usado em Sistemas TN-C-S?
TN-C-S systems need more attention.
In a TN-C-S system, PEN is combined at one part of the system and separated into PE and N at another point.
Before the PEN is separated, there is no independent neutral and PE. After the PEN is separated, the system behaves more like a TN-S section.
So the SPD selection depends on the installation point.
| Ponto de instalação | Common SPD Choice | Razão |
|---|---|---|
| Before PEN separation | 3P SPD | L1, L2, and L3 are protected to PEN. N and PE are not separated yet. |
| After PEN separation | 3P+N or 4P SPD | N and PE are available as separate conductors. Treat this section more like TN-S. |
| Inside final distribution board | Confirm project drawing | The correct structure depends on N-PE path, RCD arrangement, and project requirement. |
This is a common source of mistakes. A buyer may say, “My system is TN-C-S, please give me 4P SPD.” But the supplier still needs to know where the SPD will be installed.
Qual SPD Deve Ser Usado em Sistemas TN-C?
In a TN-C system, neutral and protective earth are combined as PEN.
There is no separate N and PE conductor at the installation point.
For this reason, a three-pole SPD is commonly used for L1, L2, and L3 protection to PEN.
A 3P+N SPD is normally not used before PEN separation because there is no separate N-PE path.
Tabela de Seleção: TT vs TN-S vs TN-C-S vs TN-C
| Earthing System | Neutral Available? | PE Separate? | Common SPD Choice | Nota do Comprador |
|---|---|---|---|---|
| TT | Sim | Sim | 3P+N / 3+1 | N-PE surge protection is important |
| TN-S | Sim | Sim | 3P+N or 4P | Check 3+1 or 4+0 design |
| TN-C-S before PEN split | No separate N/PE | Não | 3P | Protect L1, L2, L3 to PEN |
| TN-C-S after PEN split | Sim | Sim | 3P+N or 4P | Treat like TN-S section |
| TN-C | PEN only | Não | 3P | Do not assume 4P is needed |
| TI | Depends | Depends | Project-specific | Ask engineer or supplier |
Diferença de Fiação: SPD 3P+N vs SPD 4P
For this topic, the wiring diagram is very important.
A text explanation is not enough for many buyers. A panel builder needs to see the real protection paths.
3P+N SPD Typical Concept
A common 3P+N / 3+1 SPD structure uses:
- L1 to N
- L2 to N
- L3 to N
- N to PE
The first three paths are usually MOV-based. The N-PE path is often GDT or spark-gap based.
4P SPD Typical Concept
A common 4P / 4+0 SPD structure uses four voltage-limiting protection paths.
The actual wiring path depends on the product design and the manufacturer’s circuit diagram.
This is why the drawing must be checked before ordering.
Aplicações Comuns
3P+N and 4P SPDs are widely used in low-voltage three-phase distribution systems.
| Aplicação | Common Requirement |
|---|---|
| Quadro de distribuição principal | Type 1+2 or Type 2 SPD depending on lightning risk |
| Quadro de subdistribuição | DUP tipo 2 |
| Commercial building panel | 3P+N or 4P depending on earthing system |
| Armário de controle industrial | Type 2 SPD with clear wiring diagram |
| Painel elétrico OEM | Confirm 3+1 or 4+0 before production |
| Solar AC combiner / AC distribution side | Confirm grid system and SPD type |
| Telecom or equipment room panel | Often requires remote signal contact |
Erros Comuns ao Comprar
Mistake 1: Thinking 4P Is Always Better Than 3P+N
More poles do not always mean better protection.
A 4P SPD may be correct for one system. A 3P+N SPD may be better for another.
The right choice depends on the earthing system and internal circuit.
Mistake 2: Treating 3P+N and 4P as the Same Product
They may both have four modules. But the protection structure may be different.
A 3P+N SPD often has a special N-PE module. A 4P SPD may not.
Always check the circuit diagram.
Mistake 3: Ignoring TT / TN-S / TN-C-S Differences
A product that works in TN-S may not be the best choice for TT.
A product selected after PEN separation may not be correct before PEN separation.
The grounding system is not a small detail. It decides the SPD structure.
Mistake 4: Choosing Only by Uc Voltage
Uc is important. But Uc alone does not decide whether you need 3P+N or 4P.
For example, 275V, 320V, and 385V SPDs may all exist in different pole configurations.
You need to confirm both the electrical rating and the internal wiring structure.
Mistake 5: Not Confirming RCD Position
In some installations, RCD coordination can affect SPD selection and wiring.
This is especially important in TT systems.
Before ordering, confirm whether the RCD is upstream or downstream of the SPD. If you are not sure, send the panel drawing to the supplier.
Como Escolher: Processo de Decisão Simples
Step 1: Confirm the Earthing System
Check whether the system is TT, TN-S, TN-C-S, TN-C, or IT. Do not guess.
Step 2: Confirm N and PE
Check whether neutral and PE are separate, or whether PEN is still combined.
Step 3: Confirm the Circuit
Ask whether the project requires 3+1, 4+0, N-PE spark gap, or another structure.
Step 4: Confirm SPD Type
Choose Type 1+2 or Type 2 according to the installation position and project requirement.
Seleção Recomendada para Compradores
For most B2B buyers, the product name is not enough.
A better inquiry format is:
We need an SPD for a three-phase distribution board.
System: TT / TN-S / TN-C-S.
Voltage: 230/400V.
Required configuration: 3P+N / 3+1 or 4P / 4+0.
SPD Type: Type 2 or Type 1+2.
Uc: 275V / 320V / 385V.
Remote signal: yes / no.
Please recommend a suitable DIN rail SPD with wiring diagram.
This gives the supplier enough information to recommend the correct model.
Checklist Antes do Pedido
Before choosing 3P+N or 4P SPD, confirm these details:
- Earthing system: TT, TN-S, TN-C-S, TN-C, or IT
- Whether neutral is available
- Whether PE is separate from neutral
- Whether PEN has already been split
- Installation position in the panel
- SPD type: Type 1, Type 1+2, or Type 2
- Required structure: 3+1 or 4+0
- N-PE protection requirement
- Uc voltage
- In, Imax, and Iimp rating
- Backup fuse requirement
- Remote signal contact
- RCD position
- DIN rail space
- Required standard or certificate
- OEM label or private label requirement
Direção de Recomendações de Produtos
Option 1: 3P+N Type 2 SPD
Suitable for many TT and TN-S distribution boards where Type 2 protection is required.
Common for commercial distribution boards, sub-distribution panels, OEM electrical panels, and building power distribution.
Option 2: 3P+N Type 1+2 SPD
Suitable for installations with higher lightning exposure or main distribution boards where lightning current discharge capacity is required.
Common for main incoming panels, buildings with external lightning protection, overhead line supply, and industrial power distribution.
Option 3: 4P Type 2 SPD
Suitable where the project drawing specifies a 4-pole / 4+0 design.
Common for TN-S distribution boards, project-specific panel designs, and markets where 4P SPD is the standard naming practice.
Option 4: 3P SPD
Suitable for TN-C systems or TN-C-S systems before PEN separation.
Common for three-phase systems without separate neutral, L1/L2/L3 to PEN protection, and industrial boards with combined PEN at the installation point.
FAQ
O SPD 3P+N é o mesmo que o SPD 4P?
Não. Eles podem parecer semelhantes, mas podem ter circuitos internos diferentes. Um SPD 3P+N geralmente significa um design 3+1 com um módulo de proteção N-PE especial. Um SPD 4P geralmente significa um design 4+0 com quatro caminhos de proteção de limitação de tensão. Sempre verifique o diagrama de fiação.
Qual é a diferença entre 3+1 e 4+0 SPD?
Um SPD 3+1 geralmente tem três caminhos de proteção fase-neutro e um caminho de comutação de tensão N-PE. Um SPD 4+0 geralmente tem quatro caminhos de proteção de limitação de tensão. A maior diferença é como a proteção neutro-terra é tratada.
Qual SPD eu devo usar para um sistema TT?
For many three-phase TT systems, a 3P+N / 3+1 SPD is commonly selected because N-PE surge protection is important. However, the final choice should follow the project design, local standard, and manufacturer wiring diagram.
Qual SPD devo usar para um sistema TN-S?
Para sistemas TN-S, tanto as configurações 3P+N quanto 4P podem ser utilizadas, dependendo do projeto. O comprador deve confirmar se o projeto requer um circuito 3+1 ou um circuito 4+0.
Posso usar SPD de 4P em vez de SPD de 3P+N?
Nem sempre. Um SPD 4P pode não ter a mesma estrutura de proteção N-PE que um SPD 3P+N. Se o projeto exigir proteção 3+1, não o substitua por um SPD 4P sem verificar o diagrama do circuito.
O SPD de 4P é melhor do que o SPD de 3P+N?
Não, 4P não é automaticamente melhor. 3P+N e 4P são estruturas diferentes para sistemas diferentes. A melhor escolha depende do sistema de aterramento, arranjo do neutro e requisitos de fiação.
O que devo enviar ao fornecedor antes de fazer o pedido?
Envie o sistema de aterramento, a tensão do sistema, o diagrama de fiação do painel, o tipo de SPD, a tensão Uc, a classificação da corrente de descarga, os requisitos de sinal remoto e se você precisa de serviço de etiqueta OEM ou de etiqueta privada.
Precisa de Ajuda para Escolher entre 3P+N ou 4P SPD?
If you are not sure which SPD structure is suitable for your three-phase distribution board, send us your system voltage, grounding system, and panel wiring diagram.
LEEYEE can help recommend a suitable SPD configuration for distribution boards, OEM electrical panels, and private label SPD orders.
