Recently, the National Energy Administration has successively issued two notices on the development and construction of photovoltaic power plants and their safe production management, emphasizing the safety issues of photovoltaic power plants. The "Notice on Strengthening the Safety of Distributed Photovoltaic Power Generation (Draft for Solicitation of Comments)" clearly puts forward the requirements for photovoltaic power plants to install modules with rapid shutdown functions: “Install arc fault circuit breakers or use components with corresponding functions to realize arc intelligent detection and quick cut-off functions"; "PV modules shall have a safe shutdown protection function to ensure that the DC voltage outside the system sub-array is lower than the safe voltage after the inverter shuts down and the AC power is off.”

The potential safety hazards of photovoltaic power plants cannot be underestimated. Regarding the issue that high-voltage and direct current still exist after the power outage of photovoltaic power plants, the notice from the Energy Administration has already proposed specific solutions. However, whether the current loop can be "quickly" cut off in the first time when danger occurs after installing components that nominally claiming having a "quick" shutdown function or not? It has become the most concerned issue of photovoltaic users.

Herein, Projoy Electric Co., Ltd (hereinafter referred to as "Projoy") conducted an on-site test for its newly launched PEFS-PL series module-level rapid shutdown.

Test Methods

After the RSD device is connected to the power station system, the inverter and the grid, we simulate the power failure of the power grid and get the high temperature caused by partial component shielding, and shut down the normal fire button to realize shutdown of protection function of the shutdown device. Our tester clamped the oscilloscope current clamp to the output line of the shutdown device and use the oscilloscope waveform to detect the output current waveform to determine whether it is on or off.

Test Results

If the temperature exceeds 85°C, Projoy RSD will automatically cut off the current;

20A current turn-off response time is less than 10ms;

It will automatically reset when it is powered on again after it is turned off, and it only takes 33μs (<1ms) from open to closed;

The actual test results of the power station show that Projoy's module-level Rapid Shutdown

● The temperature inside the shell can be monitored in real time, and the DC current can be automatically cut off when the internal temperature exceeds 85°C, which plays an important role in preventing the expansion of fire in the first time.

● The breaking speed is extremely fast, which can cut off the current between the photovoltaic module and the inverter within 10ms, so that the modules cannot form a current loop to minimize the risk of fire.

● It can be reset automatically after the power is on, no need to turn on manually.

Recently, an article on the fire protection effectiveness of inverter isolation switches is quite popular in the photovoltaic industry and has aroused widespread discussion. The article pointed out that when the photovoltaic panel string is reversely connected or current is reversed, it is very easy to burn the circuit and cause fire. When the internal short-circuit current cannot be disconnected, external safety devices must be added to prevent fire risks. Projoy's PEFS-PL series module-level rapid shutdown, with intelligent monitoring, fast breaking speed, automatic reset and other functions, is the best choice to ensure the safe and efficient operation of the photovoltaic power station system.