Qual é a diferença entre os Dispositivos de Proteção contra Surtos (SPD) CC Tipo 1 e Tipo 2 e como escolher o correto para o meu sistema fotovoltaico?

Essa é uma distinção fundamental, pois o uso do tipo errado pode resultar em riscos à segurança ou em proteção inadequada. DPS Tipo 1 (Classe I): projetado para descarregar correntes transitórias de alta energia, normalmente provenientes de descargas atmosféricas diretas. É caracterizado pela forma de onda de 10/350 µs. São obrigatórios em sistemas com proteção externa contra raios (por exemplo, um para-raios no mesmo edifício) ou em grandes fazendas solares em escala de serviços públicos. Eles são instalados no ponto de distribuição principal. SPD Tipo 2 (Classe II): projetado para lidar com surtos induzidos de baixa energia (transientes de comutação e descargas atmosféricas indiretas), caracterizados pela forma de onda de 8/20 µs. Esses são os SPDs mais comuns usados em caixas combinadoras fotovoltaicas comerciais e residenciais e na entrada CC do inversor. Como escolher: Se o seu painel fotovoltaico estiver em um campo aberto com um para-raios, você precisará de um SPD Tipo 1 no combinador do painel principal. Se estiver instalando um sistema de telhado padrão sem um para-raios externo, um SPD Tipo 2 geralmente é suficiente. Sempre verifique o código elétrico local (NEC 690.41 nos EUA) quanto aos requisitos obrigatórios.

Se minha tensão CC for de 1000 V, mas a folha de dados do SPD listar "Tensão operacional contínua máxima (Ucpv) como 1100 V", esse SPD é adequado para meu sistema?

Sim, esse SPD provavelmente é adequado e, de fato, a margem de tensão é uma boa prática. Isso está relacionado ao conceito de "sobretensões temporárias" (TOV). O princípio: a tensão máxima de operação contínua (Ucpv ou Uc) é a tensão que o SPD pode suportar continuamente sem se degradar. Em sistemas fotovoltaicos, a tensão não é perfeitamente estável. Ela flutua com a temperatura e a irradiação. A margem de segurança: Você deve selecionar um SPD em que o valor Uc seja pelo menos 1,2 vezes a tensão de circuito aberto do sistema (Voc stc). Por exemplo, para um sistema de 1000 V CC, a Uc recomendada geralmente é de cerca de 1100 V CC ou mais. Por que a margem extra? Se você escolher um SPD com uma Uc que corresponda exatamente aos 1000 V do seu sistema, um aumento de tensão em temperatura fria (que aumenta a tensão do painel) poderá fazer com que a tensão do sistema ultrapasse o limite de Uc, fazendo com que o SPD opere (curto-circuito) desnecessariamente ou falhe prematuramente. Uma Uc mais alta garante que o SPD "passe" por essas flutuações normais de tensão e só seja ativado durante um evento de surto real.

Guia técnico do dispositivo de proteção contra surtos de corrente contínua

A DC surge protective device (SPD) limits transient overvoltage and diverts surge current away from equipment. For solar PV, the key questions are where the device is installed, whether it is rated for the maximum PV open-circuit voltage at the lowest expected temperature, and how it coordinates with the inverter and other protective devices. This guide focuses on the PV DC side; battery, EV and telecom DC systems require separate application checks.

What does a DC SPD do?

A surge may be induced by nearby lightning or switching. An SPD connected across the relevant conductors remains non-conducting under normal voltage and conducts during a transient, limiting the voltage seen by equipment. It is one part of a protection system: bonding, earthing, cable routing and appropriately rated overcurrent protection still matter. An SPD cannot guarantee survival of a direct strike or replace a fuse or circuit breaker.

DC surge protective device selection for photovoltaic systems

Key ratings to check on the datasheet

U_CPV / U_c: maximum continuous operating voltage. On a PV array, compare it with the calculated maximum string open-circuit voltage, including the cold-temperature increase. Do not select from nominal operating voltage alone.
U_p: voltage protection level at the stated test condition. Compare it with the equipment impulse withstand and allow for installation lead voltage drop. Lower is not automatically better if the continuous voltage rating is unsuitable.
I_n and I_máximo: discharge ratings under the specified 8/20 μs test waveform. Compare products only when the waveform, test class and rating basis are the same.
I_imp: impulse current rating for a Type 1/Class I device, stated with its test waveform. It is not interchangeable with I_máximo.
Short-circuit and disconnector information: check the manufacturer’s PV fault-current rating, required backup protection, connection scheme, status indicator and replacement instructions.

PV standards and the scope of this guide

IEC 61643-31 specifies test requirements for SPDs on the DC side of PV generators and inverters with rated voltages up to 1,500 V DC. Its scope excludes PV systems that include energy storage. IEC 61643-32 provides application guidance for PV SPD selection, installation and coordination. For a battery or another low-voltage DC application, check the applicable product standard and the exact device certification; a PV-only declaration is not proof of suitability for that circuit.

Type 1 or Type 2: how to decide

Type 1/Class I devices are tested for lightning-current impulses; Type 2/Class II devices are tested for induced and switching surges. The required class and placement depend on the building lightning protection system, separation distance, local installation rules and the project risk assessment. A rooftop array does not automatically require Type 1, and an open-field array does not automatically make one specific device or position correct. Use the project lightning-protection design and the manufacturer’s coordination instructions.

Where to install protection in a PV system

Review the array or combiner-box side, the inverter DC input and the AC side of the inverter as separate protection points. The number and position of SPDs depend on cable lengths, earthing arrangement and equipment withstand ratings. Keep SPD connections short and route conductors according to the installation instructions; long leads can increase the voltage reaching equipment. See our guia de proteção de inversores solares e PV protection overview for the wider design context.

Can an AC SPD be used on a DC circuit?

Do not assume that an AC-only SPD is suitable for a PV DC string. The continuous voltage, disconnection behavior, available fault current and certification must all match the DC application. Read our AC SPD on DC systems article for the failure modes and selection checks.

A practical PV SPD selection checklist

Calculate maximum PV string open-circuit voltage at the site’s lowest design temperature.
Confirm the SPD is intended and certified for the PV DC application and that U_CPV covers the calculated voltage.
Choose the test class and discharge ratings from the lightning protection design and local installation rules.
Compare U_p with the protected equipment’s withstand rating and account for the installed wiring.
Check earthing arrangement, polarity and the manufacturer’s connection diagram.
Confirm backup protection, fault-current limits, disconnector/status indication and environmental enclosure ratings.
Coordinate devices at multiple protection points using the manufacturer’s instructions; do not infer coordination from kA numbers alone.

What about batteries, EV chargers and telecom DC?

These systems have different voltage ranges, source behavior and fault-current conditions. Do not transfer a PV SPD specification automatically to a battery rack or EV charging DC bus. Obtain the device’s declared application and test standard, check maximum continuous voltage and fault current, and follow the system integrator’s protection design. For context, see our EV charging and energy storage article.

Price and procurement

A reliable price comparison needs the same application, voltage rating, test class, discharge ratings, pole configuration, enclosure and certification documents. Generic online price bands do not establish that a device is suitable for a particular installation. Ask the supplier for the model-specific datasheet, declaration or test report, wiring diagram, backup-protection requirements and quotation.

Perguntas frequentes

Is a 1,100 V DC SPD suitable for a 1,000 V PV system?

The nominal system label alone is insufficient. Calculate the array’s maximum open-circuit voltage at the lowest design temperature and compare it with the SPD’s stated U_CPV. Also verify the connection scheme, fault-current conditions and manufacturer instructions. There is no universal 1.2× multiplier that can replace this calculation.

Uma classificação de kA maior significa sempre uma proteção melhor?

No. Compare the same test waveform and class, then consider voltage protection level, continuous voltage rating, installation location and coordination. A larger single rating cannot compensate for an unsuitable voltage rating or incorrect wiring.

Conclusão

The safest way to choose a DC SPD is to start with the actual circuit and the equipment to be protected, then verify the device’s ratings, application scope and installation instructions. For PV projects, use IEC 61643-31 product documentation and IEC 61643-32 application guidance alongside local rules. Explore Kuangya DC SPD products and request model-specific technical documents before specifying a device.