Remote control+monitor 3phase

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3phMonitorControl
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Remote control+monitor 3phase

#1 Post by 3phMonitorControl » 16 Aug 2018, 13:12

Hi - this is my first post - hopefully in the right place :).

I am looking for a device that can help me measure the current of my 3kw 3phase electric water heater and remotely switch it on and off either through wifi or GSM. I am aware of the Sonoff R2 POW, but that is only for 1phase devices - can anyone recommend any devices for 3phase boilers with a similar price to the Sonoff?

Thanks - appreciate any advice!

TD-er
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Re: Remote control+monitor 3phase

#2 Post by TD-er » 16 Aug 2018, 21:44

I know there are some DIN rail energy meters, like those from Eastron.
Those are a bit expensive and support is experimental at this moment in ESPeasy.

To switch it on/off, I would certainly look for something with a proper well-known brand on it.
Switching real power (anything above a few amps) with a Sonoff is a bit tricky when you look at their tiny relais used.
And maybe you shouldn't use a normal relais, but just a SSR (solid state relais), since these switch at 0V of the sinus.
Just make sure to use a bit higher rated versions, since there are a lot forgeries out there which are proper ones, but relabeled.
Those SSR just act like a LED on the ESP side.
There are 3-phase versions. I am not sure if these can also be exchanged for 3x 1-phase versions.

Just make sure to take high currents serious!

Zodiac69
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Re: Remote control+monitor 3phase

#3 Post by Zodiac69 » 17 Aug 2018, 19:30

You can still use the SONOFF to switch your 3kw 3phase electric water heater.
Use the SONOFF to energies a 3-phase Contractor.
The contractor can handle the 3-phase and the current, where the SONOFF only drive the contractor energizing coil that only require 1.6W.
Something like this - https://www.schneider-electric.com/en/p ... contactor/
Depending on your arrangement you will either need a 3 pole - 3phase or a 4 pole 3phase and neutral.

3phMonitorControl
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Re: Remote control+monitor 3phase

#4 Post by 3phMonitorControl » 27 Aug 2018, 14:43

Thanks guys - very useful info. I guess the problem I would still face is that even if a energise a contactor using the Sonoff device, I would need to add additional clamps to measure each of the phases separately to get an accurate idea of active power consumption.

TD-er
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Re: Remote control+monitor 3phase

#5 Post by TD-er » 27 Aug 2018, 17:24

3phMonitorControl wrote:
27 Aug 2018, 14:43
Thanks guys - very useful info. I guess the problem I would still face is that even if a energise a contactor using the Sonoff device, I would need to add additional clamps to measure each of the phases separately to get an accurate idea of active power consumption.
A 3-phase power meter should take care of that.
So if you select one that's easy to monitor, then that part is of no concern any more.
For example one with a S0 bus, or maybe Eastron has 3-phase meters (using Modbus, not M-bus) ?

kimot
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Re: Remote control+monitor 3phase

#6 Post by kimot » 27 Aug 2018, 22:29

And why measure current or power for heater?
Heater has got constant resistance - so current and power is always constant with constant voltage.
You only need to know, if heater is on or off and if you control heater by controller, you always know its state.
And if you use independent heater built in thermostat, simply check voltage behind thermostat.
( optocoupler, glowing lamp and so on )
For example, my water heater has got power consumption 6kW.
When thermostat is on - built in lamp lights.
I check this lamp by fototransistor and when it is on, I now that heater consumes 6kW.
I do not need measure current - it is always 6kW.

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