Suggestions for the installation location of SPDs

 In the electrical system, surge protevtion devices (hereinafter referred to as SPDs) are like safety guards, protecting the safety of electrical equipment. Their installation locations are not determined at random, but strictly follow relevant standards and specifications. Only by comprehensively considering standards and actual factors and accurately determining the installation location of SPDs can the effectiveness of SPDs be fully utilized to provide a reliable "protective umbrella" for electrical equipment. In the electrical systems of buildings and industrial equipment, the standard analysis is as follows:

Standard compliance

1.GB 50057-2010 “Design code for protection of Sturctures against lightning” states that Class I, Class II, and Class III SPDs should be installed at the bottom of circuit breakers or fuses to ensure that lines and equipment are protected in a timely manner in the event of overvoltage such as lightning, to prevent failures and damage caused by overvoltage.

2.GB 50343-2012: "Technical code for protection of building electronic information system against lightning" requires that the SPD for distribution lines be installed at the lower port of the circuit breaker, which can protect subsequent lines and equipment and prevent power surges from damaging the electronic information system.

3.GB/T 16895.22: "Low-voltage electrical installations-Part 5-53 : Selection and erection of electrical equipment-Devices for protection for safety, isolation, switching, control and monitoring" indicates that the SPD should be installed at the lower end of the main circuit breaker of the device. This position allows the SPD to protect against possible surges before the overcurrent protector is activated, ensuring the safe operation of the electrical equipment.

Recommended installation location

1.Quick response advantage：One of the outstanding characteristics of SPD is its extremely fast response speed, which can react to surges within nanoseconds. This fast response capability enables SPD to start working the moment a surge is generated, quickly limit the voltage amplitude, and protect the back-end electrical equipment from the impact of excessive surge voltage.

2.Shorten the surge propagation path：Installed at the lower end (load side) of the incoming circuit breaker, close to the power distribution side of the protected equipment, it can effectively reduce the distance before the surge reaches the protected equipment. This can reduce the interference of the surge to other equipment during the propagation process, and at the same time reduce the loss of surge energy, so that the energy of the surge when it reaches the protected equipment is lower, reducing the risk of damage to the equipment.

3.Easy to inspect and maintain：When the SPD fails due to aging, the circuit breaker of this circuit can be directly disconnected during maintenance without affecting the upstream circuit. This greatly improves the convenience and safety of maintenance, reduces the impact on the entire power supply system, and reduces maintenance costs and power outage time.

Conclusion: In the electrical protection system, the reasonable arrangement of the SPD position is crucial to ensure the safety of equipment and personnel. Therefore, installing the SPD at the lower end of the main circuit breaker is a more reasonable solution.