Hi,
I am working on project for home energy monitoring. Problem is in Saudia arabia it has dual voltage supple
127/220 V . Kindly guide how to achieve for it and how CT needs to be installed
Not familar with this power setup, is it similar to USA:
If you can tell us which system your supplier uses according to the IEC terminology here, that would be helpful. From the plugs and sockets listed, it would appear that there are two more-or-less separate systems for the two voltages, unlike the North American system where you, the consumer, have access to both 120 V and 240 V.
If you are using the BS1363 plug (Type G in this list), then everything that applies to the UK should be correct for you.
If you are using the Type A or B plug and you have an earthed neutral, then again everything that applies to the UK should be correct for you, except for the different voltage.
It is only if you have a 3-wire supply (not counting the protective earth conductor) that you need to worry about a CT on two wires as is needed in N.America.
1 Like
The colours against each MCB indicate that you have a 3-phase system, and as you say “dual voltage”, that must mean that the line-line voltage is 220 V and voltage of each line to neutral is 127 V.
To measure the total power and energy consumed, you need 3 CTs, one on each incoming line conductor.
An emonPi is not sufficient for your needs, as it has only two inputs for CTs. You must have an emonTx or an emonTx Shield, or build your own equivalent.
If you are content with an estimate of apparent power based on the nominal supply voltage, then you don’t need an a.c. adapter (but you will need a 5 V USB power supply for an emonTx) and the default sketch in the emonTx is suitable for you.
If you want to know real power, you also need one a.c. adapter. Then you will need to download and install a “3-phase” sketch. The “standard” 3-phase sketch might not be suitable as it expects the a.c. adapter to be connected line-neutral (i.e. 127 V in your case) but if your socket and a.c. adapter is 220 V, we have a variant of that sketch that is suitable. Therefore, we need to know whether you have a socket outlet available (close to the distribution board) where you can measure the voltage, and what voltage that is.
Thanks for the quick reply. So Inshorts
3 Phase Power
Voltage between a phase line and netural => 127V
and Voltage between a phase and phase is 220V
Now I can directly connect adapter to line and neutal in the panel by hard wiring for identifying real voltage
For Detecting 220V real voltage I dont have switch near by would be possible to direct wiring in the circuit breaker for getting 220V ?
I don’t think the US a.c. adapter (120 V, 60 Hz) would be safe to use on your 127 V, 50 Hz supply, therefore I think you need to use the UK or Euro version, but on 127 V. You will need to provide a suitable socket outlet.
It is perfectly OK to use the a.c. adapter at reduced voltage to measure the supply voltage, but you will not be able to use it to power an emonTx, so you must also have a 5 V USB adapter for the power supply.
Agree I was thinking about measuring 220V on this panel . Can i directly connect to the panel 3 phase wires ?
The problem is there’s a 60° phase shift between the 127 V line-neutral and the 220 V line-line voltages, so you’d need some serious modification to the sketch to accommodate that. This is why I suggested using the a.c. adapter at half-voltage.
Suppose I just measure current flowing all 3 phases using 3 CT and add it up this would give total current
As I have problems with measuring voltage. Can I multiple with voltage to get the consumption ?
It would Vx(I1+I2+I3) . Would this formulae work ?
If you use the correct voltage (127 V), then that formula will give you the total apparent power. It will not accurately match the number that your electricity supplier uses to charge you, because their meter will read real power. Their reading will never be greater than yours, it must always be the same or lower, depending on your overall power factor.