How to Select the Right SPD for Your EV Charging Station?

The rapid growth of EV charging infrastructure brings new electrical protection challenges. Without proper surge protection devices¹ (SPDs), your charging station risks damage from lightning strikes and grid surges, leading to expensive repairs and downtime.

To select the right SPD for an EV charging station, you need a Type 1+2 combined device² with minimum 20kA discharge capacity³ per pole. Ensure protection for both AC and DC sides⁴ with appropriate voltage protection levels⁵ (Up) that match your equipment’s immunity threshold while considering the outdoor environmental factors.

As a manufacturer with over a decade in electrical protection components, I’ve seen surge damage destroy expensive charging equipment that could have been prevented with proper SPD selection. Let me guide you through the critical factors to consider when choosing surge protection for your EV charging infrastructure.

What Lightning Protection Requirements Should EV Chargers Meet?

The exposed location of most EV charging stations creates a perfect target for lightning strikes. Without robust surge protection, direct and indirect lightning can fry sensitive electronics and create safety hazards for users.

EV charging stations require Type 1+2 combined SPDs capable of handling both direct lightning strikes and induced surges. These SPDs must comply with IEC 61643-11 standards⁶ and provide a minimum discharge current (In) of 20kA per pole, with a voltage protection level (Up) under 1.5kV.

Understanding Lightning Protection Classes

The lightning protection requirements⁷ for EV charging stations vary depending on their installation location and exposure risk. Let’s break this down into practical categories:

For most commercial charging stations, I recommend not cutting corners on lightning protection. In my experience working with charging infrastructure providers across Southeast Asia, those who installed higher-rated SPDs than minimum requirements saw significantly better equipment longevity, especially in lightning-prone regions.

The key technical requirement here is coordination between the SPD’s protection level (Up) and the charging equipment’s impulse withstand level⁸. Most EV charging equipment has an impulse withstand of 2.5-4kV, so your SPD should have a Up value at least 20% lower than this threshold to ensure effective protection before the surge reaches damaging levels.

How Should AC and DC Surge Protection Be Coordinated?

Many installers make the mistake of protecting only the AC input of charging stations, leaving the DC side vulnerable. This oversight often results in damaged power electronics and converter modules.

Effective coordination requires separate SPDs for both AC and DC sides⁴ of the charging station. The AC side needs Type 1+2 SPDs installed at the main distribution panel, while the DC side requires specialized DC SPDs with appropriate voltage ratings matched to the charging output level.

Critical Protection Points in EV Charging Systems

Proper surge protection requires a systematic approach to identify all vulnerable points in the charging system. Based on our manufacturing experience, I’ve compiled this practical guide:

The coordination between these protection points is crucial. I’ve seen installations where mis-matched SPD types created protection gaps, allowing surges to bypass the protection system. The best practice is to follow the cascaded protection approach⁹, ensuring each protection stage has properly coordinated energy handling capacity and response time.

For DC protection specifically, the SPDs must be designed to handle DC voltage without creating arc faults. Standard AC SPDs will fail catastrophically if installed on DC circuits, creating additional safety hazards beyond the original surge threat.

Which SPD Ratings Are Needed for Different Charging Power Levels?

Higher power charging stations not only deliver more current to vehicles but also represent a larger investment to protect. The appropriate SPD ratings must scale with charging power.

For Level 1 (up to 7.2kW) charging, Type 2 SPDs with 20kA discharge capability are sufficient. Level 2 (up to 22kW) requires 40kA rated Type 1+2 SPDs. DC fast charging (50kW+) demands specialized 50kA+ Type 1+2 SPDs with DC protection on the output side.

SPD Selection Guide by Charging Power Level

Choosing the right SPD capacity involves analyzing both the charging station’s power rating and its value as an asset. Through our testing and customer feedback, I’ve developed this practical selection guide:

The most overlooked aspect in my experience is the voltage protection level (Up). While many installers focus on discharge capacity, the Up value determines how much voltage can still reach your equipment during a surge event. For sensitive electronics in modern charging stations, I recommend selecting SPDs with the lowest possible Up value, even if this means a premium price.

For commercial charging installations with multiple charging points, I also recommend SPDs with remote monitoring capability¹⁰. This allows operators to quickly identify when protection has been compromised after surge events, preventing subsequent damage from leaving charging points unprotected after the first surge.

How Do Temperature and Outdoor Environment Affect SPD Selection?

EV charging stations face harsh environmental conditions that most indoor electrical equipment doesn’t encounter. Temperature extremes, moisture, and pollution can all compromise SPD performance if not properly accounted for.

For outdoor EV charging applications, select SPDs with an operating temperature range¹¹ of at least -40°C to +70°C (-40°F to +158°F). The enclosure should have a minimum IP65 rating¹² for weather protection, and the SPD should include thermal disconnection technology¹³ to prevent fire hazards.

Environmental Factors in SPD Selection

From my experience supplying components across diverse climate regions, I’ve learned that environmental adaptability¹⁴ is critical for reliable SPD operation. Here’s how different environmental factors should influence your SPD selection:

Beyond these general guidelines, altitude also plays an important role in SPD selection. For every 1000m above sea level, the air’s dielectric strength decreases, potentially affecting SPD performance. For high-altitude installations¹⁶ (above 2000m), SPDs should be derated or specially designed for such applications.

I recently worked with a charging network operator in a coastal area of Southeast Asia where standard SPDs were failing within 6-8 months due to corrosion. By switching to marine-grade SPDs with enhanced environmental protection, they extended the service life to over 3 years, significantly reducing their maintenance costs and downtime.

Заключение

Selecting the right SPD for your EV charging station requires balancing lightning protection needs, AC-DC coordination, power level matching, and environmental considerations. With proper selection and installation, you’ll ensure reliable operation and protect your investment.