Connecting inverters in open delta

[gumbey1@yahoo.com]

Good day to you all,can you connect two single phase inverters in open delta? If yes how do you calculate the output protection? also if there three inverters,example(2-6kw and 1-10kw) connected in delta what would be the output protection for the system?

 

[jaggedben]

For calculating line currents, see this article:
http://solarprofessional.com/articl...ng-3-phase-line-currents?v=disable_pagination

It's not simple math for an unbalanced system.

As far as whether it's possible to connect to an open delta, I would first of all consult the inverter manufacturer. And I would also get approval from the utility before going ahead with the project.

 

[ggunn]

For calculating line currents, see this article:
http://solarprofessional.com/articl...ng-3-phase-line-currents?v=disable_pagination

It's not simple math for an unbalanced system.

What I usually do in such a case is size all the OCPD to the worst case and size the conductors accordingly. For example, if I were to have two 8kW and one 6kW single phase inverters connected phase to phase in a three phase system, I would probably size the OCPD at the service and the conductors to the combiner panel as if it were three 8kW inverters.

 

[Smart $]

Prior to 2014 Code, it's pretty simple really. Inverters are single phase. Conductors and protection are based on max output rating... and OCPD is also single phase. After aggregated, conductors and OCP ratings are based on the sum of breaker ratings... which will always be greater than max output ratings combined, where output currents are out of phase.

It is only under 2014 Code that you might want to do the vector math. There is nothing that says you have to. It only matters after combining the outputs in a delta connection. Before combining is still the same. Upon and after combining can be greater than the "math" determination, so a breaker sum will still work.

 

[gumbey1@yahoo.com]

Prior to 2014 Code, it's pretty simple really. Inverters are single phase. Conductors and protection are based on max output rating... and OCPD is also single phase. After aggregated, conductors and OCP ratings are based on the sum of breaker ratings... which will always be greater than max output ratings combined, where output currents are out of phase.

It is only under 2014 Code that you might want to do the vector math. There is nothing that says you have to. It only matters after combining the outputs in a delta connection. Before combining is still the same. Upon and after combining can be greater than the "math" determination, so a breaker sum will still work.

Thanks to you all ,got the information needed from the web site that was given.