DC Surge Protection Device

Choosing the right KRIPAL DC SPD is critical for system safety.

Focus on these four key parameters tailored to our product range:

Maximum Continuous Operating Voltage (Uc):
This must be higher than the maximum DC voltage of your PV system (considering factors like cold-temperature voltage rise). KRIPAL offers a wide range of Uc values across our SPI, SPB, SPC, and SPD series to match various system voltages./

Voltage Protection Level (Up):
This indicates the residual voltage that reaches your equipment. A lower Up value means better protection. Ensure the Up of the KRIPAL SPD is lower than the impulse withstand voltage of your sensitive inverter and other equipment.

Nominal Discharge Current (In) and Maximum Discharge Current (Imax):
These represent the SPD's ability to divert surge currents. Higher values indicate greater durability against lightning strikes. Our Class B SPI series, for example, is engineered with very high In/Imax ratings for the main service entrance.

• Uc (Max. Continuous Operating Voltage):The maximum DC voltage at which the KRIPAL SPD can operate continuously and safely without degradation.
• Up (Voltage Protection Level): The maximum voltage that will be measured across the SPD's terminals when it is in operation. A low Up, as found in our SPC and SPD series, ensures delicate electronics are safe.
• In (Nominal Discharge Current): The peak value of a current wave (8/20 μs) that the KRIPAL SPD can withstand multiple times without damage. This tests its durability.
• Imax (Maximum Discharge Current): The peak value of a current wave (8/20 μs) that the SPD can withstand at least once. This represents the maximum surge handling capability.

Proper installation is key to ensuring optimal performance.

• Correct Location: Install the SPD in the DC distribution box, as close as possible to the inverter input. This provides the most direct protection for your most valuable asset.
• Short and Thick Leads: The connecting wires to the SPD must be as short and thick as possible to minimize the additional impedance in the surge current path, which can lead to a higher let-through voltage.
• Reliable Grounding: The grounding conductor must be securely connected to the main earth terminal. The system's ground resistance must comply with local electrical codes to ensure surge currents can be dissipated safely into the earth.
• Upstream Overcurrent Protection: A KRIPAL DC SPD must be protected by a suitably rated DC fuse or circuit breaker to safely disconnect it in the rare event of a catastrophic failure.

KRIPAL DC SPDs are equipped with a clear visual indicator window (e.g., green for OK, red for fault) and, on some models, a remote alarm contact. Once the indicator shows a fault (e.g., turns red), it signifies that the internal components (like the varistor block) have degraded and the protective function is lost. You must replace the module immediately. Continuing to operate with a failed SPD leaves your entire PV system vulnerable to the next surge event.

The service life of a KRIPAL DC SPD is not defined by time alone, but by its exposure to surge events. Its lifespan depends on the number and intensity of surges it has diverted.

• Even without a fault indication, we recommend inspecting your SPD during routine system maintenanceand replacing it per the manufacturer's guidelines.
• After a direct lightning strike or a severe thunderstorm, a prompt inspection or replacement is highly advised, even if the indicator appears normal, as the cumulative damage may have reached its limit.