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Wireless contactors - any good?


Snapper

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Hi folks

I see a few wireless contactors on the market but not much in the way of user reviews. Has anyone had experience with these?

My situation: I’ve got an SunSync 8kva inverter powering my house (everything is on it, no non-essential separation). The inverter sits about 25m from the DB and there’s no physical way to get a second cable between the two for non-essential load. So I’m wanting to shut off non-essential loads when grid power is down and thought a wireless contactor could be the answer. 
 

Can a wireless contactor do this and are the reliable? For example, what happens if comms is lost between the transmitter (on grid side) and receiver (on DB side) is lost? I’d want it to kill the non-essential load in that kind of situation. 
 

Any thoughts or suggestions are welcome. 
 

thx 

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13 minutes ago, BigBear said:

 

Thanks, I've seen those but I couldn't figure out whether they work at all when the Internet connection is down? The reviews imply that an internet connection is required, which would be a concern for me. I need a robust solution. 😐

 

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3 minutes ago, Snapper said:

 

Thanks, I've seen those but I couldn't figure out whether they work at all when the Internet connection is down? The reviews imply that an internet connection is required, which would be a concern for me. I need a robust solution. 😐

 

The only time i have had offline notifications is if Eskom is down and device is on non-essentials side of inverter or if the CB going to the device is off or Tripped.

There is manual override button on the front of the ASC, which works great if you want geyser etc. on or off just press the button.

Timer, Scheduling etc. is all done from the app and the only time the timer failed to activate is when device or CB is off

My WiFi is always on but can test what happens if it is offline or if cbi cloud is unavailable.. not that I have experienced any of those so far.

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59 minutes ago, BigBear said:

The only time i have had offline notifications is if Eskom is down and device is on non-essentials side of inverter or if the CB going to the device is off or Tripped.

There is manual override button on the front of the ASC, which works great if you want geyser etc. on or off just press the button.

Timer, Scheduling etc. is all done from the app and the only time the timer failed to activate is when device or CB is off

My WiFi is always on but can test what happens if it is offline or if cbi cloud is unavailable.. not that I have experienced any of those so far.

 

Thanks, sounds interesting. Do you have this working like a contactor (IOW, when grid goes down, it instantly kills the power to the non-essential loads)?

 

If so, how does the CBI device know about the grid power going down? 

 

 

Edited by Snapper
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1 hour ago, Snapper said:

 

Thanks, I've seen those but I couldn't figure out whether they work at all when the Internet connection is down? The reviews imply that an internet connection is required, which would be a concern for me. I need a robust solution. 😐

 

The unit cannot get to the APP if it has no power or it has lost contact due to no Internet. Both these conditions will send a notify to the cell as per below. This is for Sonoff via Ewelink.

You don't need a special contactor. You can use the Sonoff to drive any contactor coil and that can do the switching. 

As far as your question. If no Internet to the Sonoff the it cannot operate to alert you or allow you to control it or change timer settings etc. That's why you get the alert of off line status. 

 

Exame of notify with LS this morning. 

IMG_20230426_133133.thumb.jpg.f86cedcd083578f990aec3a64afb4768.jpg

Edited by Scorp007
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3 minutes ago, Scorp007 said:

The unit cannot get to the APP if it has no power or it has lost contact due to no Internet. Both these conditions will send a notify to the cell as per below. This is for Sonoff via Ewelink.

 

Exame of notify with LS this morning. 

IMG_20230426_133133.thumb.jpg.f86cedcd083578f990aec3a64afb4768.jpg

Ok I see. So one can presumably script or configure a shutdown event from that notification?

I’m not sure that would work for my needs though - I need non-essential loads killed instantly if grid goes down, or else the excess draw could trip my inverter. 🫤

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5 minutes ago, Snapper said:

Ok I see. So one can presumably script or configure a shutdown event from that notification?

I’m not sure that would work for my needs though - I need non-essential loads killed instantly if grid goes down, or else the excess draw could trip my inverter. 

OK I see it now. You will need a power point not on the inverter 

That power point can be the input to the inverter as that goes off when grid is off. 

Edited by Scorp007
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I never just answer the question posed but try to understand the actual requirement that lead to the question.  An old varsity lecturer taught me that and referred to it as " 'n bose ontwerp".
 

2 hours ago, Snapper said:

My situation: I’ve got an SunSync 8kva inverter powering my house (everything is on it, no non-essential separation). The inverter sits about 25m from the DB and there’s no physical way to get a second cable between the two for non-essential load. So I’m wanting to shut off non-essential loads when grid power is down and thought a wireless contactor could be the answer. 

From your problem statement I am confused why you need a wireless solution.

You could create a non-essential circuit fed from a high-current contactor mounted in, or close to your DB.  If Eskom  goes on strike, the grid powered contactor would drop out, disconnecting the non-essentials.  But that begs the question, why run the non-essentials through the SunSynk in the first place?  Perhaps I misunderstand you.

I doubt that you would find wireless relays that could handle the full 40+ amps that your non-essentials might need.  Normally these devices have a 15 or 20A limit.  You would then need to add yet another contactor capable of the required current.

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4 minutes ago, Modina said:

I never just answer the question posed but try to understand the actual requirement that lead to the question.  An old varsity lecturer taught me that and referred to it as " 'n bose ontwerp".
 

From your problem statement I am confused why you need a wireless solution.

You could create a non-essential circuit fed from a high-current contactor mounted in, or close to your DB.  If Eskom  goes on strike, the grid powered contactor would drop out, disconnecting the non-essentials.  But that begs the question, why run the non-essentials through the SunSynk in the first place?  Perhaps I misunderstand you.

I doubt that you would find wireless relays that could handle the full 40+ amps that your non-essentials might need.  Normally these devices have a 15 or 20A limit.  You would then need to add yet another contactor capable of the required current.


 

The reason for a wireless (as opposed to wired) contactor would be that I don’t have Eskom power coming in to the DB, or anywhere near it. And there’s no way to run a new cable in to that location. So the entire house is powered by the inverter, which is outside the building. I have no choice. If I used a wireless contactor with transmitter out at the Eskom side of the inverter (in another building about 20m from the DB in the house) then I could have non-essential items disconnected when grid power goes down. 
 

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Ah, now I get it.  One always assumes the main DB to be the origin of your grid power.

Many moons ago people used the mains wiring as a communication bus.  For instance intercoms and even computer networks up to about 5 mbps.   Basically one adds a high frequency carrier onto the mains.  That's how the geyser controllers worked where Eskom/Municipality would remotely switch off your geyser.

You could use one of those old geyser contactors, I just don't know where you find the "sender" that would need to be mounted at the SunSynk.  I am sure your SunSynk would block any Eskom/Muni control signal that might still be used.

 

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Here is another idea, not sure how practical:

Your 20m cable I presume is an underground cable.  Those cables are required to have an armoured steel sleeve.  It might be possible to use the steel sleeve as an extra conductor to carry a low voltage/power (say 12V AC or DC) between it and N or GND.  For instance, one could use a small 10VA 12V 50Hz transformer that always sits on the grid and powers a contactor remotely.  Your supply cable might not have an extra unused conductor?  

Correction: Keep it AC.  We know what the sparkies have to say about DC.  DC could also lead to possible galvanic corrosion.

Edited by Modina
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1 hour ago, Snapper said:

Ok I see. So one can presumably script or configure a shutdown event from that notification?

I’m not sure that would work for my needs though - I need non-essential loads killed instantly if grid goes down, or else the excess draw could trip my inverter. 🫤

Do you have WiFi at the inverter at all times powered from the essential side? 

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1 hour ago, Snapper said:


 

The reason for a wireless (as opposed to wired) contactor would be that I don’t have Eskom power coming in to the DB, or anywhere near it. And there’s no way to run a new cable in to that location. So the entire house is powered by the inverter, which is outside the building. I have no choice. If I used a wireless contactor with transmitter out at the Eskom side of the inverter (in another building about 20m from the DB in the house) then I could have non-essential items disconnected when grid power goes down. 
 

I suppose there are only so many non-essentials. Have you considered wiring them directly to the Aux of the inverter?

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Just now, frivan said:

I suppose there are only so many non-essentials. Have you considered wiring them directly to the Aux of the inverter?

Yeah, unfortunately that comes back to the problem of running cable. The non-esentials (geyser, aircon, etc.) are all close to the DB but nowhere near the inverter.

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1 hour ago, frivan said:

I would be surprised if a wireless solution works flawlessly. If you don't want to run twinflex for a contactor, you could run instrumentation cable to a solid state relay. 

Just like you I cannot understand why can one not run 2 thin wires of any kind for the 20m needed. 

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