In today's society, with the rapid popularization of electric vehicles (EVs), the number of EV chargers, an essential supporting infrastructure, continues to grow. However, during operation, EV chargers face many potential electrical risks, among which surge events are particularly prominent. Surges, also known as transient overvoltage and overcurrent, may be caused by lightning induction, power grid switching operations, or load start/stop events, posing serious threats to EV chargers and the equipment connected to them. Therefore, the installation and application of Surge Protective Devices (SPDs) are of vital importance to ensuring the safe and stable operation of electric vehicle charging systems.
Whether it is a residential AC charger or a commercial DC fast charger, EV chargers are typically deployed outdoors and must remain continuously connected to the power grid during operation. This makes them particularly vulnerable to surge events. When a surge occurs, the transient overvoltage may far exceed the design limits of the EV charger, triggering a series of problems.
Minor surges may lead to degraded performance or accelerated aging of components. For example, charging efficiency may decrease, charging time may increase, or communication functions may malfunction, preventing normal information exchange between the EV charger and the electric vehicle or other devices. Severe surges, however, may cause complete equipment failure and even damage other connected circuits and devices. For instance, printed circuit boards (PCBs) inside the EV charger may be burned out, insulation materials may be punctured, and short circuits or fires may occur. This not only damages the EV charger itself but may also endanger surrounding facilities and personnel. In addition, fault currents may flow back through the DC output to the EV battery pack, causing battery failure and affecting the vehicle's normal operation and safety.
Given the severe hazards surges pose to EV chargers, appropriate surge protection for EV chargers is not only critical for preventing equipment damage and extending service life, but also a key measure for ensuring the overall safety and stability of the charging system. From the perspective of industry standards and regulations, surge protection for EV chargers has gained widespread global recognition and has become a mandatory requirement in many regions.
For example, IEC 61643-11 is a globally adopted standard for SPDs in low-voltage distribution systems. It specifies the performance and test methods for surge protective devices used in electric vehicle supply equipment (EVSE). UL 1449 (5th Edition) is the standard for the North American market, defining relevant requirements for SPDs used in EV chargers. In China, GB/T 34120-2017, as a national standard for charging equipment, requires EV chargers to be equipped with at least Type II surge protection. In addition, the United Nations Economic Commission for Europe (UNECE) Regulation R10 (Revision 4) is an international automotive regulation that requires onboard chargers (OBCs) to pass lightning surge and electrical fast transient/burst tests to ensure electromagnetic compatibility (EMC) and overvoltage protection. These standards consistently emphasize that surge protection is a core element of EV charger safety design and a fundamental prerequisite for compliant installation and user safety.
In practice, not all EV charger models are equipped with built-in surge protection modules. Many cost-sensitive users, when selecting residential EV chargers, may encounter products on the market that only provide basic circuit designs without dedicated surge protective devices (SPDs) or clearly defined overvoltage protection mechanisms. Some high-end brands may integrate basic surge suppression components inside the EV charger, but their performance is often limited by cost constraints and internal space.
Therefore, both consumers and engineers should proactively check whether products carry effective surge protection certifications (such as IEC or UL) and give priority to brands that have passed international testing standards. Even when an EV charger includes built-in surge protection, its capability is usually quite basic. Built-in SPDs in EV chargers generally have small capacity and can only handle minor surges. They function more effectively as part of a multi-level surge protection system when coordinated with stronger upstream external protection measures. Without external protection, built-in SPDs are likely to fail when exposed to severe lightning strikes or significant power grid fluctuations.
To effectively protect EV chargers and connected equipment from surge damage, the industry widely recommends a layered surge protection design. This approach includes installing a whole-building surge protector at the main distribution board as the primary barrier, along with built-in SPDs within the EV charger as the final line of defense at the equipment level. Through coordinated internal and external surge protection, surges of varying intensities can be effectively dissipated, proper voltage coordination between protection levels can be achieved, and overall reliability and service life can be significantly improved.
It is strongly recommended to install a Type 1 or Type 1+2 surge protective device (SPD) at the main distribution panel. This external SPD can handle higher lightning currents and power grid surge energy, serving as the first line of defense. It effectively absorbs most high-energy surges, thereby protecting the entire electrical system and all connected equipment. When selecting an external SPD, parameters such as rated voltage, rated current, and protection level must be considered to ensure compatibility with the electrical characteristics of the EV charger and suitability for local grid conditions.
Dedicated lightning and surge protective devices for EV chargers are primarily used to protect both the charging equipment and electric vehicles from lightning strikes and power grid surges. When selecting such devices, it is essential to first understand the EV charger's rated voltage, rated current, and operating frequency, in order to choose a surge protector that meets the charger's requirements. EV chargers are generally divided into DC EV chargers and AC EV chargers, and different types may require different surge protection devices.
For DC EV chargers, due to their higher operating voltage, typically ranging from 200 V to 1000 V DC, DC surge protective devices capable of withstanding high voltage should be selected. It is recommended to use high-grade DC SPDs with protection levels of 60 kA or higher, ensuring effective protection against lightning strikes during fast charging and preventing damage to both the EV charger and the electric vehicle. For AC EV chargers, which operate at lower voltages, generally 220 V or 380 V AC,SPDs suitable for AC power systems should be selected. Lower-grade AC SPDs with protection levels of 20 kA or 30 kA are typically sufficient to meet lightning protection requirements.
During installation of dedicated surge protectors for EV chargers, the protection level should be selected based on the EV charger's environment and surrounding lightning conditions. Generally, for critical equipment such as EV chargers, higher protection levels are recommended to ensure safe operation. Proper layout of surge protectors is also essential to ensure coverage of critical equipment and circuits, while minimizing the length of electrical connections to reduce the impact of lightning surges. In addition, choosing reliable surge protection brands is crucial to ensure product quality and performance in compliance with relevant standards.
When lightning induction or power grid fluctuations occur, power supply lines may experience transient overvoltages far exceeding the tolerance of equipment, often reaching several kilovolts. EV charger surge protectors equipped with SPD functionality, which normally remain in a high-impedance state, will immediately become conductive and safely divert excess current to ground through dedicated grounding conductors, thereby protecting the equipment. Without SPD protection, all surge energy would be directly injected into the EV charger's internal power components (such as IGBT modules and control boards), resulting in irreversible damage.
With the widespread adoption of electric vehicles, the safety and reliability of EV chargers have become a major focus of attention. Surge protection, as a critical measure for ensuring the safe operation of EV chargers, is undeniably important. By understanding the hazards surges pose to EV chargers, the importance and industry recognition of surge protection, the current status and selection of surge protection solutions, the implementation strategies for surge protection, and the working principles of SPDs, we can better appreciate the necessity of installing appropriate surge protection devices in EV charger systems.
Whether from the perspective of equipment safety, extended service life, overall system stability, or user safety, surge protection plays an indispensable role. Therefore, EV charger manufacturers, installers, and users alike should place strong emphasis on surge protection, select appropriate surge protection devices.
