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Which shelly to use to read status of a relay contact


JPol

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Hi Shelly community

I have Shelly to control devices via Home Assistant.  All my Shelly's switch on or off devices.

Now my question:

I have a heater that is controlled by an internal contactor controlled inside the heater.

So, I would like to detect whether this contactor is on or off. There is still a free contact on this contactor

so I could connect whatever I want ot it.

 

Which shelly device should I buy to hook up to this free contact to see whether the contactor is on/off? 

Edited by JPol
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Welcome!

 

There are many options, e.g. a Shelly Plus 1 Mini would be sufficient for your project.

Do you have further information about the manufacturer/type of the contactor? Is it a contactor with auxiliary contact (potential-free)?

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It is a Schneider Electric with 4 switcheable contacts but only 2 are used (mono fase) to switch on/off the heating element.

So, there are two contacts that are available and they are both dry contacts, therefore fully potential free - there is nothing connected to them

and they open/close together with the switching of the contactor.

The intent is now to use one of these contacts to connect the Shelly and sense whether the contactor is on or not.

How do I connect it now ?

1) obviously L and N: connected to 230V

2) I assume SW is not used because I am not going to switch anything

3) I and O are the ones that are left. So how do I connect now the Shelly?

Thanks

Jean-Paul

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Plus 1 Mini was chosen because it is the cheapest alternative to implement your project.

9 minutes ago, JPol said:

How do I connect it now ?

1) obviously L and N: connected to 230V <--- yes

2) I assume SW is not used because I am not going to switch anything <--- SW is required, this shows you the switching status

3) I and O are the ones that are left. So how do I connect now the Shelly? <---remain unused

The same phase (L) as connected to the Shelly for power supply is connected to the I of the dry contact on the contactor, the O contact switched by the contactor is then connected to the SW input of the Shelly.


You can display the status of whether the contactor is switched or not in the app or in the WEB UI (here th red bar for OFF / its ON then green). You can also further process the status using scenes or actions.

Screenshot2024-01-25at12-34-27ShellyControl.png.5e810c31fe134eecd86f47abec343b0e.pngScreenshot2024-01-25at12-30-25ShellyControl.png.879c8fc0f1eaf52fbc63f91a3fcb28b4.png

Screenshot2024-01-25at12-34-16ShellyControl.png.1bf598b7d5f3337fc9169026449cd0ff.pngScreenshot2024-01-25at12-37-23ShellyMini1G3.thumb.png.2fd9bb93972779a494a1ddd9910fe5ca.png

 


The I and O of the Shelly Plus 1 Mini can be unused or used for other purposes if you want to switch something smart and potential-free.

Important: in input/output settings, the button type must be 'detached' so that the internal relay in Shelly can still be switched via the app or the web UI or via automation. The SW input is then detached from the relay

 

Screenshot2024-01-25at12-34-02ShellyControl.thumb.png.11c8b4b3e9fc288314266e88ceafaad5.png

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Dear Olsche

This is fantastic, exactly what I was looking for.

I learned a lot via your answer.

Reading via SW and even having a possibility at the same time to switch something smart with the same Shelly. Just genious !

Big thank you

Jean-Paul

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