rapid shutdown switch1
In recent years,With the rapid increase in distributed PV installations , safety concerns have become widespread. Reports show that most PV plant accidents are fires, with 80% of these fires caused by DC high voltage producing DC arcs. Additionally, since distributed PV systems are typically installed in densely populated areas, any problems that occur can result in significant loss of life and property.
Therefore, to eliminate DC high voltage in emergency situations, protect the safety of firefighters, and maintain system safety, many countries require PV plants to install component-level rapid shutdown devices.
In traditional PV systems, DC high voltage poses a significant safety threat, with 80% of fires caused by DC arcs. In traditional PV plants, multiple components are connected in series, resulting in a voltage multiplication effect that can reach up to 1500V, or DC high voltage. During the long-term operation of a PV plant, device failures, insulation aging, and loose electrical connections are inevitable, which can lead to poor contact, insulation material damage, and decreased insulation impedance, resulting in frequent DC arc faults caused by DC high voltage, increasing the risk of fires and electric shock.
safe switch 1
Once a PV system catches fire, the DC arc will cause the system to continue burning, making it difficult to extinguish. On the other hand, there may still be hundreds or even thousands of volts of DC high voltage in the burning system. At this point, if firefighters attempt to rescue people, it can lead to tragic consequences. Therefore, emergency personnel usually have to wait for the PV plant to burn down completely before they can start working, which often leads to serious delays in firefighting.
In this case, if the PV plant is equipped with a rapid shutdown device, firefighters can simply turn off the switch to quickly reduce the danger of the power system, lowering the voltage to a safe level.
The rapid shutdown device ensures personnel safety and timely maintenance of the PV plant. In the event of a fire or other emergency at a PV plant, maintenance personnel or firefighters can simply turn off the device to quickly disconnect the connection between each PV module, eliminating the DC high voltage in the PV system array, protecting the safety of firefighters, and allowing the PV plant to be maintained in a timely manner, minimizing property damage.
For example, ONCCY’s string-level rapid shutdown switch ERS can receive a “run allowed” signal in normal operation, allowing the PV system to operate normally. In an emergency, maintenance personnel or firefighters can simply cut off the power to the rapid shutdown switch or activate the emergency stop switch, and the rapid shutdown switch can quickly disconnect the connection between each component within 30 seconds, cutting off the DC high voltage on the DC side, reducing the voltage to 80V within 30 cm of the system and 30V beyond 30 cm.
At this point, firefighters can safely extinguish the fire and rescue people, and the PV plant can be maintained in a timely manner, minimizing property damage.