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How does a surge protection device (SPD) work?
In industrial electrical installations, operational reliability depends directly on the systems' ability to withstand faults and external disturbances. One of the most common, and also most damaging, phenomena is electrical surges, which can compromise sensitive equipment, reduce the lifespan of components, and even cause unexpected production stoppages.
To mitigate these risks, Surge Protection Devices (SPDs) have become an indispensable ally, especially in low and medium voltage electrical panels.
What is a DPS?
A surge protection device is equipment designed to protect electrical and electronic systems against transient overvoltages. These surges can be caused by lightning strikes, switching operations on the electrical network, switching of large loads, or even internal faults in the installation.
In simple terms, a surge protection device (SPD) acts as a "safety valve" for unwanted currents, diverting them to the grounding system before they reach equipment and cause damage.
How does surge protection (SPD) work?
When an overvoltage occurs, the surge protection device (SPD) starts conducting and directs the excess energy to ground. As soon as the overvoltage is dissipated, it returns to its normal isolation state, without interfering with the operation of the circuit.
This functionality ensures that equipment connected to the system receives only the correct voltage, preventing failures and increasing the lifespan of the installation.
Voltage classes of a surge protection device (SPD).
According to technical standards, surge protection devices (SPDs) are classified according to their application and level of protection:
DPS Class I: the first line of defense
Used at power entry points, such as main low-voltage switchgear, these devices are designed to withstand extremely high surge currents resulting from direct lightning strikes.
Class II SPD:
Used in distribution boards and secondary panels, these devices protect against surges that may have passed through the first barrier or originated internally in the installation.
Class III SPD:
Installed near sensitive equipment, such as automation and instrumentation systems. These devices offer response times of less than 25 nanoseconds and extremely low residual voltage limitation, typically less than 1.5 times the equipment's nominal voltage.
What technical standards address surge protection devices (SPDs)?
The main requirements for surge protection devices (SPDs) are described in national and international standards:
NBR IEC 61643-11: establishes the requirements for surge protection devices in low-voltage systems.
IEC 62305: deals with protection against lightning strikes and related protective measures.
NBR 5410: Brazilian standard for low-voltage electrical installations, which defines guidelines for the use of surge protection devices (SPDs).
Following these guidelines is essential to ensure that the device performs its function safely and efficiently.
Operation of surge protection devices (SPDs) in low and medium voltage electrical panels.
In low and medium voltage switchgear, surge protection devices (SPDs) play a strategic role in protecting critical systems.
In low-voltage applications, they protect industrial loads, automation systems, lighting, and IT equipment against network surges. In medium-voltage applications, they are used in switchgear and substations to protect transformers, large motors, and auxiliary systems.
Integrating surge protection devices (SPDs) into our BTM PowerFlex panels ensures greater reliability for installations that cannot risk unscheduled shutdowns, such as power plants, continuous process industries, and critical infrastructure.
The Surge Protection Device (SPD) is a relatively simple component, but it plays an essential role in protecting and ensuring the continuity of industrial operations.
By integrating surge protection devices (SPDs) into low and medium voltage panels, it is possible to prevent critical failures, preserve equipment, and ensure the safety of people and facilities.
At BTM, we develop complete solutions that consider the importance of surge protection from the design stage, ensuring efficiency, safety, and compliance with technical standards.
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