Shelly 1PM not able to operate non-resistive load?

    • Autor

    I just connected my first Shelly device, and my first device to control was a simple power regulating device for resistive floor heating cable. The floor heating cable is 2kW, and the original power regulating device is Microreg MRC-16 which controls the time in 30 minutes interval the cable is on. In this way setting the controller to 50% would give 1kW consumption. So by putting in a 1PM I wanted to restrict the operation to night-time only due to electricity price.

    I have connected the N pin of 1PM to one of the three live wires in my system as I do not have any defined neutral wire (I have 230V IT distribution, not TN as most of the world), the same wire connected to N of the MRC-16.

    The L of 1PM is connected to another of the three live wires in my system, and the Output of 1PM is connected to L of the MRC-16. The SW pin on 1PM is not in use, therefore only 3 pins of 1PM is in use in my setup.

    WIth this connection I manage to power up the MRC-16 and see a momentary load of 2kW on my house power meter. But the power dies away just as quickly. Is this due to the relay of the 1PM and that it needs to see at least a small resistive load? It works fine if I connect the heat cable directly to the 1PM not using the MRC-16.

    Would you please double check if the relay of the Shelly 1PM is turned on?

    Did you set an maximum power protection limit in „safety“ settings:

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    • Autor

    Yes, the relay clicks, and I do measure 238V between N and O on the PM1. The LED indicating "ON" of the MRC-16 is also active. The problem is that there is no voltage on the LOAD connection of the MRC-16 where the heating cable is connected. So while writing this I halted for 5 minutes and went back down to check if the relay of the MRC-16 was broken..............

    Back again! Of course, the behaviour is caused by the MRC-16! I didn't use it for heating this winter due to the electricity prices, so when I heard the relay of MRC-16 and the LED powering up I just didn't think the fault was in the original system. But the relay of the MRC-16 must be the guilty even though it clicks (it does not hold the contact closed).

    Too long time doing administrative office work and forgetting my actual engineering background is my only excuse, and now I am pretty embarrassed :S .