DC Surge Protection Device Application
Solar PV Combiner Boxes: String‑level PV SPD for solar arrays (PV DC surge protector).
Battery Energy Storage: DC SPD protection for battery inverters and UPS systems.
Telecom & Data Centers: Safeguards 48 V and 240 V DC power feeds against transient spikes.
Industrial Control Panels: Protect PLCs, sensors, and automation equipment from switching surges.
Security & CCTV Systems: Maintains uninterrupted DC supply for cameras and access controls.
How to Correctly Size a Surge Protective Device (SPD) for Your Power System
A surge protective device prevents high‑energy voltage spikes from reaching sensitive equipment, averting potential damage.
If Properly Designed, How Does an SPD Work in a DC System?
In a DC setup, the DC SPD averts excessive voltage—beyond equipment ratings—by safely discharging surplus energy between DC conductors (or AC conductors in AC systems). When equipped with a ground terminal, the SPD also tracks voltage differences between the ground and the protected conductors. During a surge, it channels energy to the ground, provided the grounding path is low‑resistance.
Note: SPDs are not meant to handle sustained over‑voltage conditions lasting seconds or minutes. Proper system design and component sizing must prevent prolonged voltage excess.
Steps to Safeguard Your Equipment During Voltage Surges：
Ensure Solid Grounding：
Confirm that both your system and SPD have a low‑resistance earth connection.
Match “Uc” Ratings:
Select an SPD whose maximum continuous operating voltage (Uc) on the datasheet is at or just above (0–10 V higher) your system’s maximum DC or AC voltage. If Uc far exceeds your equipment’s rating, the SPD won’t activate at the correct threshold and may fail to clamp damaging transients.
Protect Key Inputs:
At minimum, install SPDs on the PV input of your charge controller or inverter/charger. If connecting to the public grid, also shield the AC input.
Choose the Right Voltage Type:
Use SPDs rated for DC applications on PV conductors, and AC‑rated SPDs on AC lines.
How Surge Protective Devices Minimize PV Plant Downtime
SPDs are crucial for reducing downtime caused by electrical surges in photovoltaic plants. When planning a PV installation, incorporate SPDs to guard against both surges and grid disturbances, ensuring steady energy production and reliable distribution.
Why DC Surge Protection Device a Top Priority in PV Plants?
Solar arrays face harsh outdoor conditions—rain, wind, dust—and, most critically, lightning. Lightning poses two main threats:
- Direct Strikes: Can physically devastate rooftop panels and inverters.
- Induced Overvoltages: Magnetic coupling can send damaging spikes through DC/AC cabling, harming sensitive electronics like PCBs.
For direct‐strike defense, External Lightning Protection (ELP) per IEC 62305 is mandatory where risk assessments indicate. ELP systems (air terminals, mesh cages) steer lightning current via copper down conductors safely into the earth.
However, ELP alone doesn’t stop transient overvoltages within the electrical circuits. That’s where SPDs come in: installed in parallel with circuit breakers, they divert surge energy to ground and clamp voltage to levels safe for downstream equipment.
Important: After implementing ELP, an SPD must also be fitted. Even without full ELP coverage, adding SPDs is highly recommended to tame transient surges and uphold uninterrupted PV plant operation.
