How to connect 3P+N and an extra appliance


I have 4 EmonTX. I’d like to measure my house input(3 Phases + Neutral, 220V between phases), using 3 EmonTX(One for each phase) and I’d like to monitor a specific appliance(A 3000W resistance) using another EmonTX.

My doubt is that this appliance is 220V, it uses 2 of the 3 phases. 1 EmonTX is OK to measure, or I need 2 EmonTX to monitor the consumption in this appliance?

Attached a rough drawing. Do I need this CT2 in the appliance measuring?!

Note 1: Also, there is a Neutral not in the schematic.

Well, I found this:

If the circuit is purely 240 V, i.e. there is no neutral connection, again only one CT is required. However, the power must be doubled, as the voltage measured is only half the voltage applied to the load, as in Fig 4c.

In this case, how to double the power?

Don’t look at the N.America pages - you do not have the same supply system. Yours is much more like the European system, except Europe is 230 L - N, or 400 V L - L; or our system (240 V single phase domestic or 415 V 3-phase industrial).

If you are using one emonTx to measure only the load connected L1 - L2, then you need one 230 V a.c. adapter (if you want or need an a.c. adapter) and one c.t. There is no need for the second c.t. because it would measure the same current as the other one, and you must not double the voltage because in N.America, they only measure half of the supply voltage - 120 V - with their split single phase supply.

Looks, great! I’ll work on that. Thanks!