Artur Posted July 18 Share Posted July 18 Hi! I connected the Shelly PRO 3EM to my electrical installation. For a week, everything was fine. It worked without any issues. Last night, we had a huge storm. The circuit breakers tripped. When I turned them back on in the morning, everything worked for about 5-10 minutes before the circuit breakers tripped again. When I disconnect the Shelly, the installation works fine. So the problem is with the Shelly. Did the storm damage the device, and is it beyond repair? If so, is there a way to protect a new one in the future? Thanks for help, Artur Quote Link to comment Share on other sites More sharing options...
Members mschaeffler Posted July 18 Members Share Posted July 18 How have you connected the device? Can you make a sketch, please. Is you house suppllied with underground cable or aerial cable? Do you have a overvoltage protection? What product? It is recommended to use fuses (200mA, sand filled, with a breaking current) at the three current supplys. 1 Quote Link to comment Share on other sites More sharing options...
Artur Posted July 20 Author Share Posted July 20 @mschaeffler Thanks for reply. The power line is overhead. However, from the pole to the house, the wire goes underground to the garage to the electrical box. It seems to me that we don’t have any additional overvoltage protection. In the electrical box with the meter, there are only fuses for the three phases. The Shelly was connected to the DIN rail already in the house in the electrical box. After the storm, it started tripping the entire sector of fuses after a few minutes of normal operation. Thanks for help, Quote Link to comment Share on other sites More sharing options...
tvbshelly Posted July 20 Share Posted July 20 What exactly do you mean by “it started tripping the entire sector”? The circuit breakers labeled with A/B/C, the whole line or the RCD/FI (in the picture below the shelly on the left)? The Shelly is powered via C/L3. The connections for A/B are mainly used for the reference voltage. This probably has nothing to do with your problem, but I think it's important: Please overwork your cabling and make sure the copper is not exposed (too much copper visible) and has a tight connection - this is good safety practice. Quote Link to comment Share on other sites More sharing options...
Artur Posted July 20 Author Share Posted July 20 @tvbshelly No matter where I connect the Shelly, after a few minutes of operation, it trips the main breaker for the sector it is connected to. Everything was working fine before the storm. So I think it is permanently destroyed. Quote Link to comment Share on other sites More sharing options...
tvbshelly Posted July 20 Share Posted July 20 (edited) Ah, okay, I see. This is not a circuit breaker, but an RCD/FI. In any case, it should not trigger. I find it strange that the RCD only triggers after some time has passed. But I agree with you, the Shelly may probably really damaged. Otherwise, is it possible that the storm has caused damage somewhere else in the electrical installation (outside the power box)? However, this should not cause the Shelly to trigger the RCD. Edited July 20 by tvbshelly 1 Quote Link to comment Share on other sites More sharing options...
Artur Posted July 20 Author Share Posted July 20 What is the best way to connect the new Shelly? Would connecting it to the main 3-phase input, even before the RCD/FI, be okay? Assuming that I add a dedicated circuit breaker just for it with 3 fuse links of, let’s say, 1A before it? Quote Link to comment Share on other sites More sharing options...
Members thgoebel Posted July 20 Members Share Posted July 20 A faulty Shelly pro 3EM (which cause ever) will never trip a RCD. Because the device has no PE terminal, it will never produce a fault current: Any current going in the device via terminal L must leave it at terminal N… 2 Quote Link to comment Share on other sites More sharing options...
tvbshelly Posted July 20 Share Posted July 20 (edited) It would be good if you could take a closer look at the blue N cables next to and above the Shelly. Unfortunately, the photo is not very sharp, but I have the impression that I can see bare copper in several places - this should not be the case. Please also check again whether the N for the Shelly comes from the RCD to which A/B/C from the Shelly are also connected Before inspecting / testing, please make sure that the entire distribution box is disconnected = current-free. Edited July 20 by tvbshelly 1 Quote Link to comment Share on other sites More sharing options...
Artur Posted July 21 Author Share Posted July 21 16 hours ago, thgoebel said: A faulty Shelly pro 3EM (which cause ever) will never trip a RCD. Because the device has no PE terminal, it will never produce a fault current: Any current going in the device via terminal L must leave it at terminal N… Thank you for the explanation. In that case, what could be the reason that a plugged-in and operating Shelly trips the RCD after a few minutes? Quote Link to comment Share on other sites More sharing options...
Members thgoebel Posted July 21 Members Share Posted July 21 Hardly to determine far away. Most likely is an incorrect wiring (as @tvbshelly mentioned) in conjunction with a defective device (provoked by storm) which added a certain amount of fail current. Quote Link to comment Share on other sites More sharing options...
Members Zyrkonim Posted July 21 Members Share Posted July 21 (edited) I believe, the L1, L2, L3 goes through the RCD and the neutral doesn't go trough the same RCD and probably before the storm total leakage wasn't tripping the RCD and now some added leakage on the circuit or the RCD become more sensitive, it's tripping. I don't think there is a problem with the shelly pro 3EM since there is no ground connected to it... other than a leakage through neutral if it's bad connected. I would try to identify where is the actual leakage on that circuit by disconnecting shelly and see what trip the RCD if you sure is correctly connected. As a rule, verify first all devices having ground connection usually i will look at coffee machine, water heaters, washing machine, ovens, refrigerators, water coolers, etc... mostly things that have a heater element or a motor, that are the usual suspects on a RCD tripping, when there is not instant fault sometime hard to identify the leakage without proper tools. Edited July 21 by Zyrkonim 1 Quote Link to comment Share on other sites More sharing options...
Artur Posted July 22 Author Share Posted July 22 On 21.7.2024 at 10:32, Zyrkonim said: I believe, the L1, L2, L3 goes through the RCD and the neutral doesn't go trough the same RCD and probably before the storm total leakage wasn't tripping the RCD and now some added leakage on the circuit or the RCD become more sensitive, it's tripping. I don't think there is a problem with the shelly pro 3EM since there is no ground connected to it... other than a leakage through neutral if it's bad connected. I would try to identify where is the actual leakage on that circuit by disconnecting shelly and see what trip the RCD if you sure is correctly connected. As a rule, verify first all devices having ground connection usually i will look at coffee machine, water heaters, washing machine, ovens, refrigerators, water coolers, etc... mostly things that have a heater element or a motor, that are the usual suspects on a RCD tripping, when there is not instant fault sometime hard to identify the leakage without proper tools. @Zyrkonim Yes, you are right. That was my mistake, and it is exactly as you described. I connected the neutral directly to the entry of the electrical panel. I didn’t think about it 😞 During the storm, it must have damaged the Shelly, in my opinion. I decided to conduct an experiment and connect it directly to the voltage input, bypassing the RCD, this time correctly, I hope. I expected complete damage as no fuse was protecting it anymore, and in my opinion, it was already malfunctioning. And indeed, that’s what happened. After turning it on, the device worked for a few minutes and then shut down completely. I disassembled it and found that the capacitors were damaged. But if I am wrong and still missing something, please feel free to let me know. Thank you very much for your help. It was a valuable lesson. Quote Link to comment Share on other sites More sharing options...
Members thgoebel Posted July 22 Members Share Posted July 22 The Varistor (blue disc) is damaged too, and the plug connection between power supply module and mainboard has desoldered itself. Wonder if the fusible resistor should be intact… Further faulty components could be: The rectifier diode and L5, an inductance between the two 3,3μF/400V electrolytic capacitors. List not complete… Last week, I‘ve repaired approximately 8 of these defective Shelly pro 3EM… 1 Quote Link to comment Share on other sites More sharing options...
Artur Posted July 23 Author Share Posted July 23 On 22.7.2024 at 13:28, thgoebel said: Last week, I‘ve repaired approximately 8 of these defective Shelly pro 3EM… @thgoebel What was the reason for the damage to so many units? Quote Link to comment Share on other sites More sharing options...
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