What is Type 1 Surge Protection Device？

Type 1 surge protection device: The first surge protection barrier of the power system

In places where lightning occurs frequently or where the power grid fluctuates violently, the safe operation of electrical equipment cannot be separated from the protection of surge protection.

一、What is Type 1 Surge Protection Device？

1.Meaning and core functions

The T1 Surge Protection Device is a lightning protection device designed according to the IEC 61643-11 standard. It is installed at the incoming line of the main distribution box of a building or power system. It is mainly used to intercept the 10/350μs waveform ultra-large surge current (up to 100kA or more) generated by direct lightning strikes or grid induction. Its core functions include：

Direct surge protection: quickly discharge lightning energy to the earth through the grounding system.

Voltage clamping: Limits transient overvoltage to within the tolerance range of the equipment (usually <4kV).

Energy coordination: Cooperate with Type 2 surge protection device and Type 3 surge protection device to achieve graded protection.

2. Differences from Type 2 / Type 3 surge protection device

Type 1 surge protection device

Place of installation：Main distribution Boards

Waveform tolerance：10/350μs

Discharge capacity：12.5kA-100kA

Application：Building/Industrial main distribution Boards，Substation.

Type 2 surge protection device

Place of installation：Sub-Distribution Boards

Waveform tolerance：8/20μs

Discharge capacity：20kA-40kA

Application：Building/Industrial Sub-Distribution Boards.

Type 3 surge protection device

Place of installation：Terminal equipment

Waveform tolerance：8/20μs

Discharge capacity：5kA-10kA

Application：Precision Instruments，Communication.

二、Core technical parameters of primary surge protection device

1.Key Performance Indicators

Lightning impulse current(10/350μs)[I_imp] 

Used to measure the ability of surge protection device to withstand direct lightning strikes. The typical value is 50kA (10/350μs), and high-protection grade products can reach 100kA.

Voltage protection level [U_p]

Residual voltage after surge, industrial-grade Type 1 surge protection device is usually ≤4kV.

Response time [t_A]

Nanosecond response (≤100ns)， ensures protection is activated before the surge reaches the device.

2.Core Components and Technologies

High Energy Gas Discharge Tube(GDT)

Rapidly conducts large current through gas discharge for high energy discharge.

High Energy Metal Oxide Varistor( MOV)

Assist in absorbing the remaining surge energy and reducing the residual pressure.

Thermal trip device

Automatically disconnect when surge protection device is aged or overloaded to prevent fire risk.

三、Typical applications of type 1 surge protection device

1. Power supply system and substation

Protection objects: transformers, high-voltage switchgear

Case: After installing Type 1 surge protection device in a 110kV substation, the lightning trip rate was reduced by 90%.

2. Building lightning protection system

Protection objects: building Main distribution Boards, elevator control system.

Standard requirements: GB 50057 “Building Lightning Protection Design Code” requires that Type 1 surge protection device be installed at the entrance of high-rise buildings.

3. Industrial Equipment

Protection objects: DCS system in petrochemical plants, PLC control cabinets in steel plants.

Effect: A certain automobile production line adopted Type 1+Type 2 combined surge protection device, and the equipment failure rate dropped by 70%.

4. Communication base stations and data centers

Protection objects: 5G base station power supply, server room

Typical configuration: Type 1 surge protection device (incoming line) + Type 2 surge protection device (power distribution in the equipment room) + Type 3 surge protection device (cabinet level).

四、How to choose a high-quality primary surge protection device?

Selection basis

Grid type: TN-S, TT or IT systems require surge protection device with different grounding methods.

Lightning risk level: Lightning density of the assessment area according to IEC 62305 (for example, I_imp≥100kA is required for high-risk areas).

Certification Standards

International Certification：IEC 61643-11、UL 1449 4th Edition.

China certification: GB/T 18802.11-2020, CQC voluntary certification.

五、Installation and maintenance: maximizing safety and effectiveness

1. Installation Specifications

Wiring length ≤ 0.5m: Avoid lead inductance causing increased residual voltage.

Grounding resistance ≤ 4Ω: Ensure that the leakage path has low impedance and add grounding electrodes if necessary.

Classification distance ≥ 10m: Decoupling requirements must be met between multi-level surge protection device.

2. Maintenance points

Status indication monitoring: Determine whether the SPD is invalid by window color or remote signal contact.

Annual inspection system: Test insulation resistance and leakage current during thunderstorms and before the thunderstorm season.

六、Conclusions

Although the surge protection device is small, it is an indispensable “gatekeeper” in the electrical safety system. From model selection and adaptation to scientific operation, every detail is related to the reliability of the system. In the face of increasingly complex electromagnetic environments, only by choosing high-quality SPDs that meet the GB/T 18802 and IEC 61643 standards and establishing a systematic protection plan can we truly build a solid safety line of defense.

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