The use and function of surge protector graded protection
In a society with a high level of development of modern electrical and electronic technology, various precision electronic devices are widely used in industrial production, commercial operations, family life, and information and communication fields. However, these devices are extremely sensitive to voltage fluctuations and are particularly vulnerable to damage from instantaneous overvoltages – “surges” – caused by lightning, grid switching, electrostatic discharge, etc. In order to effectively protect electrical systems and electronic equipment, surge protective devices (SPDs) are widely used. Among them, hierarchical protection is the core concept in the design of the surge protection system, which realizes the step-by-step discharge and voltage limitation of surge energy through multi-level coordination, so as to comprehensively ensure the safety of electricity.1. Sources and hazards of power surges
A power surge is a phenomenon that occurs rapidly over a very short period of time (microseconds to milliseconds). Its main sources include:
1. External factors: such as high-energy shocks caused by direct or induced lightning on power lines.
2. Internal factors: such as transient overvoltages caused by large equipment start-stop, transformer switching, capacitor switching, etc.
Although the duration of power surges is short, their peak voltages can reach thousands or even tens of thousands of volts, which is enough to break through equipment insulation, burn circuit boards, cause data loss or system paralysis, and in severe cases, cause safety accidents such as fires. Therefore, it is crucial to establish an effective surge protection system.
2. The basic principle of hierarchical protection
The hierarchical protection of surge protectors refers to the division of SPDs into different levels according to the installation location and function according to the structure and equipment importance of the electrical system, usually divided into three levels:
– Front stage (Type 1): Installed in the main distribution cabinet or inlet end of the building, it is mainly used to vent the huge surge current (such as a 10/350μs waveform) generated by direct lightning or high-energy induction lightning, which is characterized by a large current capacity (usually ≥ 50kA) but a relatively high residual voltage.
– Type 2: Installed in floor distribution boxes or at the front of important equipment to further limit power surges caused by external intrusion or internal operation, typical test waveform is 8/20μs, moderate current capacity (e.g., 20-40kA), low residual voltage, and play a protective role between top and bottom.
– Type 3: Installed near sensitive electronic devices or at the front of sockets, such as servers, surveillance systems, medical equipment, etc., for fine protection, low residual voltage, fast response speed, can effectively suppress residual power surges, and ensure the safe operation of equipment.
3. The main uses and functions of hierarchical protection
1. Realize the step-by-step release of energy
The high-energy surge is first preliminarily discharged by the pre-stage SPD to avoid the direct impact of high energy on the rear equipment. the second stage continues to absorb the remaining energy; The third stage finely filters residual voltage fluctuations. This “layer-by-layer fortification” mechanism effectively avoids the problem of single-stage protector failure due to excessive energy.
2. Optimize residual pressure levels
It is difficult for a single SPD to balance high flow capability and low residual voltage at the same time. Through hierarchical cooperation, the front stage is responsible for “carrying big waves”, and the rear stage is responsible for “ensuring fineness”, so that the voltage reaching the equipment end is controlled within a safe range and meets the requirements of the equipment withstand voltage level.
3. Improve system reliability and longevity
Graded protection reduces the load on individual SPDs, extends their service life, and reduces the probability of system exposure to power surge risks due to protector failure, improving the stability of the overall power supply system.
4. Meet the requirements of different environments and standards
Different places (such as data centers, hospitals, factories, and residences) have different requirements for surge protection. The hierarchical design can be flexibly configured according to actual needs, and complies with international and national standards such as IEC 61643 and GB 50057 to ensure compliance and safety.
5. Realize selective coordination and fault isolation
Reasonable hierarchical design can realize “selective tripping” or “status indication” between SPDs, which is convenient for troubleshooting and maintenance, and avoids affecting the entire protection system due to a certain level of fault.
4. Conclusion
In summary, the hierarchical protection of surge protectors is not only a technical optimization solution, but also a necessary measure to ensure the safe operation of modern electrical systems. Through scientific energy distribution and voltage control, it builds a robust “surge firewall” to effectively resist various transient overvoltage threats from inside and outside. In today’s accelerated process of intelligence and digitalization, strengthening the awareness of surge grading protection and rationally designing and installing SPD systems are of great significance to protect the safety of people’s lives and property and maintain the normal operation of society