Questions & Answers > Production meter for PV system

A customer is being supplied from the utility with a 3 phase 230/400 V supply. How would you meter that customer if they only wanted to connect to the grid with a 1 phase 230 V connection?

January 16, 2013 | Unregistered CommenterBDS

Thanks for the question BDS. I am not familiar with a 230/400 volt three phase system, so I am going to let my past experience lead me as I do my best to answer this for you.
Because you give two voltages from your three phase system, I believe this must be a four wire system but, I am not sure if it is WYE or DELTA. [Whether the system is WYE or DELTA may not really matter because your question is how to meter this if the customer wants to connect a 1 phase 230 volt system to your three phase system.]
The Phase to Neutral voltage is 230 volts and multiplying it by 1.732 gives the Phase to Phase voltage at 400 volts, so based upon this assumption, I am presuming this is a four wire WYE rather than a four wire DELTA. (I am thinking this could be 240/416 volt, four wire WYE system, which I am familiar with). From these assumptions I believe that the phase to neutral voltage of your three phase system is 230 volts (which is two wires: a phase and a neutral). The customer wants to deliver to you a 230 volt single phase voltage (again a 2 wire system). To meter this 230 volt, 2 wire single phase system, you would use a 2 wire, 240 volt 1S meter or a 120 to 480V auto-ranging 1S meter. Blondel’s Theorem says with a two wire system you need a single element meter to meter it correctly, which is the 1S.
If any of my assumptions are incorrect, please let me know. Also I’d like to note that I don’t consider myself to be an expert in PV systems, so if any of what I am suggesting does not fit with how you are thinking this installation will be put together, I encourage you to seek out the opinions of others who have PV expertise and/or background.
Thanks and Be Safe All Ways,

January 23, 2013 | Unregistered CommenterBrad