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Relays, Contactors and more


Tsa
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Hi All

I need some guidance please. I see guys making use of relays/contactors when  setting up their geysers and pool pumps to make use of smart switches(Sonoff, etc).

What does one need to look for when buying these? Would the below work for geyser/pool pump? 40A geyser(3kw soon to be 2kw) and 20/30A for pool pump(0.75kw)?

 

https://www.mantech.co.za/ProductInfo.aspx?Item=99M500893

https://www.mantech.co.za/ProductInfo.aspx?Item=14M0935

https://mantech.co.za/ProductInfo.aspx?Item=14M3872

and then these 2 which also differ from one another...

https://mantech.co.za/ProductInfo.aspx?Item=15M3465-X

vs

https://mantech.co.za/ProductInfo.aspx?Item=82M1467

 

TIA

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3 hours ago, Tariq said:

Why not use the Cbi Astute, it has a 30 amp capacity, circuit breaker size screws/terminals, only thing is runs on its own software, unless you can flash it

   It is DIN and Samite rail compatible 

Yeah, already have HA running so don't want to bother with something not compatible. Happy with the Sonoff and relay route. 

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5 hours ago, Vassen said:

It depends on what you are using to trigger the relay / contactor. This will dictate what coil it needs to have. 5V, 12V SC or 220V AC.

The next is to look at the switching current. It should be significantly bigger than the load current. 

I have found the one from ACDC to be decent. Its a 220V coil, with 40A switching current and costs around R80. Part number cgb-1c-230VAC

 

Thanks, that's much cheaper than the mantech ones. See they don't have stock in CPT, but will see if I can order with delivery online. 

Any chance you have a schematic of wiring this up to a pool pump/geyser with a sonoff basic? 

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This relay is fine. The only issue one has with connecting to existing circuits is where you install these devices.

To make a neat job it would be great to keep the switchgear in the main DB and control these from another board. But looking at this relay it doesn't fit in a DB with the rail type mounting that they use.

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5 hours ago, Tsa said:

Thanks, that's much cheaper than the mantech ones. See they don't have stock in CPT, but will see if I can order with delivery online. 

Any chance you have a schematic of wiring this up to a pool pump/geyser with a sonoff basic? 

Another option for the pool pump is the Sonoff POW. It's a bit light for a geyser but should be more than adequate for the pool. 

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  • 1 month later...

Thanks again for this. I would just like to confirm the following:

On 2021/02/04 at 8:39 PM, Vassen said:

Output of the sonoff basic will just connect to the 2 coil terminals of the relay, the ones on the left. 

I should be able to take the input to the current timer and route it to the Sonoff and then from the sonoff to the terminals as indicated above on the relay? What is the polarity of the terminals on the relay or does it not matter?

 

On 2021/02/04 at 8:39 PM, Vassen said:

Then you use the common and NO terminal to switch the live of the pump. 220v live goes to COM, NO goes to the live of the pump. 

I can then take the output of the current timer to the COM and then the NO connected to the pump live. Will just check what the routing of Neutral is. 

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@Vassen Sorry, will try and clarify my understanding here.

Current setup below. Please ignore the colours, my blue pen decided to die halfway. Also note I didn't draw in all the Neutrals, grounds, etc. These will remain as is. 

Main focus here is from the Pump CB to the Timer and then to the Pool Pump itself. 

image.thumb.png.f44b6281a63e365de58bccfb268e8e8e.png

 

Proposed future setup with Sonoff and Relay:

image.thumb.png.569d81e741de773030fe9c970dee86b1.png

So L from the Pump CB will now go to the Sonoff L and N from N Bar to N of Sonoff. Now the main question at #1 (in yellow) above is what is the polarity of the pins on the Relay where you indicated I should connect the Sonoff output to? 

Ignore my line at #2 (yellow) above. My question is where should the 220V Live come from to connect to the COM on the relay? Can I just take that from the output of the Pump CB as well? So from the L output of Pump CB, one to the L of Sonoff Input and one to the COM on relay?

And lastly I understood that NO from relay to the Pool Pump Live input.

Please let me know where I am going wrong? Thanks again! 

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On 2021/02/04 at 9:25 PM, Richard Mackay said:

This relay is fine. The only issue one has with connecting to existing circuits is where you install these devices.

To make a neat job it would be great to keep the switchgear in the main DB and control these from another board. But looking at this relay it doesn't fit in a DB with the rail type mounting that they use.

Yes to put it in the DB board directly would make it neat - also noting that one can purchase a Sonoff box with DIN mount.

This contactor would work for geyser as it has 25A contacts. And....it is DIN rail mounted.  Price is not too bad at R156 incl VAT. 

It looks like it breaks both L and N and I think the Sonoff only breaks the Neutral but am open to correction. 

https://www.robotics.org.za/CT1-25

CT1-25-002

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Thanks @Vassen

Thanks for the explanation and clarification. Yes, as indicated that connection from Sonoff to COM at #2 in my diagram can be ignored. I will take the L from the Pump CB to feed the contact. 

Please just clarify which is the correct way around. 

6 hours ago, Vassen said:

But you then need live from the dB, also going to the NO pin of the relay. The com pin will then go to the live of the pump. Neutral from neutral bar then goes to pump neutral. 

OR

On 2021/02/04 at 8:39 PM, Vassen said:

Then you use the common and NO terminal to switch the live of the pump. 220v live goes to COM, NO goes to the live of the pump.

220v L to COM or to NO? 

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17 minutes ago, Brani said:

It doesn't make any difference. It's like two sides of the switch. When the relay is off, the connection is broken, when the relay is on, the connection is made.

Excellent, that's what I understood from Vassen's explanation on the coil and contacts, but just wanted to be 100% sure. 

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