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Type 2 Surge Protective Device SPD

Type 2 AC Surge Protective Device SPD TRS-B100

Type 2 Surge Protective Device

Type 2 SPD is installed in the electrical distribution box to protect the load by blocking the transmission of any overvoltage. It is the main protection device for all low-voltage electrical installations. Characteristics of type 2 SPD: Current wave 8/20 µs.

Type 2 SPD is installed after Type 1 SPD and is the second line of defense in the protection system. Type 2 SPD can further suppress residual surge current and protect equipment from damage. However, Type 2 SPD cannot be used in exposed power distribution cabinets that are vulnerable to lightning strikes.

What applications is Type 2 SPD suitable for?

Type 2 SPD resists transient overvoltages caused by man-made electrical operations or indirect lightning strikes to protect equipment in electrical systems. Installed switchboards in office buildings, shopping malls, residences, factories, data centers, schools, hospitals, and public facilities to enhance the reliability of electrical equipment and improve property and personal safety. Type 2 SPD is the primary protective device for all low-voltage electrical appliances.

Specially designed Type 2 SPDs can be used in photovoltaic systems to protect them from surges. SPDs installed on the DC side need to be specifically designed for DC applications and be able to handle the nonlinear characteristics of photovoltaic currents. Type 2 AC SPD is also required on the AC side to protect connected equipment.

Where do you put a Type 2 surge protector?

Type 2 SPD is usually installed on the load side of the distribution board in the building, close to the protected equipment. The installation must comply with regional wiring regulations and choose a location that is easy to maintain.

In distribution panels, Type 2 SPDs should be located close to the main circuit breaker, which minimizes the surge protection path. For proper use of the SPD, proper wiring and grounding are critical factors. Make sure there is enough space in the installation location to facilitate future inspection and replacement.

Are there different requirements for Type 2 SPD for residential and commercial buildings?

For both residential and commercial buildings, ensuring the safety of electrical systems is critical. Since electrical loads in commercial buildings are typically larger and more complex, SPD requirements are often determined based on their use, size, and complexity of the electrical system, so it is important to install an appropriate SPD.

For residential buildings, in 2020 NEC introduced new regulations stating that all services supplying power to residential units should be equipped with Type 1 SPD and Type 2 SPD.

For commercial buildings, NEC clarified the requirements for SPD in 2023, increasing the focus on electrical safety in commercial buildings.

How to determine the power system capacity that requires Type 2 SPD?

To select a suitable Type 2 SPD to meet the surge protection needs of the power system, we need to consider the following factors: system voltage, maximum discharge current, nominal discharge current, and surge protection level.

First, you need to confirm the building power system voltage, which is the basic parameter for selecting Type 2 SPD. Consider whether the building is located in an area with frequent lightning activity, and choosing an SPD with a higher maximum discharge current ensures protection even in extreme weather. Choose an SPD with an appropriate nominal discharge current to maximize the handling of surges generated in the circuit. Note that the surge protection level of the SPD needs to be lower than the maximum voltage that the equipment to be protected can withstand.