Troubleshooting Common Rapid Shutdown Device FaultsTroubleshooting Common Rapid Shutdown Device Faults

Friends who have installed RSDs—have you ever encountered issues like "no response when pressing the test button" or "frequent tripping"? Don’t panic! It’s not that the device is broken; most of these are minor problems caused by oversights. Today, Master Wang will explain 6 common RSD issues and their solutions, combined with Fonrich’s user-friendly features—even beginners can troubleshoot on their own.

1. Most Common: RSD has no response when pressing the "TEST" button, and the light doesn’t turn on

Symptom: When trying to test if the RSD works, pressing the test button yields no response, and the indicator light remains off—leading you to think the device is faulty.

Master Wang’s Troubleshooting Steps:

• First, check if "power is connected": Fonrich RSD draws power from the modules. Verify that the main switch of the modules is turned on; if it’s off, the RSD will definitely not respond.
• Next, check if "wiring is loose": A homeowner in Nanjing once had an unresponsive RSD. Opening the distribution cabinet revealed that the "IN" terminal wire was not tightened, causing poor contact with the copper core. After tightening it with a screwdriver, pressing the test button immediately lit up the red light.
• Finally, check if "the fuse is blown": If the above two steps don’t work, the internal fuse of the RSD may be blown (e.g., due to previous reverse connection). Fonrich RSD’s fuse is on the side—simply twist it open to replace, no need to replace the entire device, saving a lot of money.

Tip: Fonrich RSD has an indicator light that turns green when powered on. If it doesn’t light up, first check the power supply and wiring before considering replacing the device.

2. Annoying: RSD trips frequently, several times a day

Symptom: The RSD trips constantly, especially during peak electricity usage (e.g., using air conditioners in summer). It trips again soon after resetting, affecting power generation.

Master Wang’s Troubleshooting Steps:

• First, rule out "genuine faults": Use a multimeter to test the module cables for short circuits or grounding (e.g., worn cable insulation touching metal brackets).
• Next, check for "false alarms": Some older RSD models cannot distinguish between "normal arcs" and "fault arcs." For example, sparks from refrigerator startup may trigger false trips. Fonrich RSD features "intelligent anti-interference" design that filters normal signals from household appliance startups. If your current RSD frequently trips falsely, try switching to Fonrich’s model.
• Finally, check if "voltage exceeds limits": Most residential PV systems are 600V DC. If you use an undersized RSD (e.g., a 300V model for a 600V system), overvoltage will cause tripping. Fonrich RSD supports a wide voltage range of 120V-1500V, compatible with 600V and 1000V systems—no need to worry about choosing the wrong model.

3. RSD can shut down, but cannot connect to the APP, and data is unavailable

Symptom: The RSD works normally during manual testing, but fails to connect to the mobile APP. Remote monitoring is unavailable, and trip records cannot be retrieved.

Master Wang’s Troubleshooting Steps:

• First, check if "the communication cable is correctly connected": Fonrich RSD’s communication cable is two-core, which should be connected to the inverter’s "RS485" or "communication port"—do not connect it to the power supply terminal.
• Next, verify "APP settings are correct": After downloading Fonrich’s supporting "SafeSolar" APP, select the correct device type and enter the inverter’s communication address. Do not use apps from other brands, as they will not detect the device.
• Finally, check "signal distance": For wireless communication RSDs (e.g., Fonrich’s WiFi model), weak signals may result from being too far from the router. Move the router closer or add a signal booster to establish a connection.

4. Strange Phenomenon: After RSD shutdown, voltage cannot drop below 30V

Symptom: After pressing the test button, the RSD shows "shutdown successful," but a multimeter test shows the DC-side voltage is still over 100V—failing to reach the safe threshold (≤30V), which violates safety standards.

Master Wang’s Troubleshooting Steps:

• First, check if "only one string is shut down": Module-level RSDs shut down a single string. If you measure the voltage of other strings, it will naturally not drop. Measure the output terminal of the "shut down string"—Fonrich RSD’s indicator light for the corresponding string turns red after shutdown, helping you locate the correct string.
• Next, check if "wiring is reversed": If the RSD’s "IN" and "OUT" terminals are reversed, only partial voltage can be cut off during shutdown, failing to drop below 30V. Fonrich RSD has an "anti-reverse lock" that prevents incorrect insertion. If your RSD lacks this design, quickly disconnect and rewire.
• Finally, confirm "the RSD model is correct": Large systems (e.g., above 10kW) require "multi-string shutdown" RSDs—single-string RSDs cannot handle them. Fonrich’s RSD-F200 is designed for large systems, capable of shutting down 4 strings simultaneously, reducing voltage to below 10V, which meets safety standards.

5. Emergency Situation: RSD does not shut down automatically, only manual cutoff works

Symptom: In case of fire or module failure, the RSD fails to detect and shut down automatically—only manual pressing of the test button works, delaying rescue time.

Master Wang’s Troubleshooting Steps:

• First, check if "detection sensitivity is sufficient": Some RSDs have low sensitivity and cannot detect mild arcs. Fonrich RSD offers "three-level sensitivity adjustment" and can detect weak arcs as low as 0.1A. If your RSD has low sensitivity, contact after-sales to adjust it.
• Next, check for "obstructions or dust": Dust covering the RSD’s detection module can affect its performance. Regularly wipe Fonrich RSD’s detection port with a dry cloth to prevent dust buildup.
• Finally, check if "the device is aging": After 5+ years of use, internal components may deteriorate—replacement is recommended. Fonrich RSD has a service life of 8 years, 3 years longer than ordinary brands, providing long-term peace of mind.

6. Minor Issue: RSD indicator light flashes randomly, unclear status

Symptom: The RSD light alternates between red and green, sometimes flashing yellow—making it impossible to tell if it’s normal or faulty.

Master Wang’s Guide to Indicator Lights (Taking Fonrich as an Example):

• Green steady on: Normal operation, no issues.
• Red steady on: RSD is in shutdown mode (may be due to detected fault or manual test button press).
• Yellow flashing: Communication error (if APP connection fails, check the communication cable or WiFi).
• Alternating red and yellow flashes: Overvoltage or undervoltage (check if module voltage is within the acceptable range).

Tip: Fonrich RSD’s manual includes an "indicator light reference table"—it’s recommended to paste it on the distribution cabinet for quick reference, eliminating the need to flip through the manual every time.

Final Summary:

When your RSD malfunctions, don’t rush to replace it. 90% of issues stem from minor problems with wiring, power supply, or settings. Following the above steps can resolve most problems. If you’re unsure or the issue persists, contact the brand’s after-sales service—Fonrich has professional technicians who can provide remote guidance. Remember: Proper troubleshooting saves time and money, ensuring your PV system operates safely and stably!