Nec 705.100

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erickench

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Brooklyn, NY
I looked at the above NEC section and this is what I see. Paragraph A specifies a rule for hybrid systems using single phase inverters. Paragraph B specifies a rule for interactive systems using three phase inverters. Why in one case is the word "hybrid" used and not in the other?
 

tortuga

Code Historian
Location
Oregon
Occupation
Electrical Design
They are including electric power production, distribution systems, and energy storage systems like batteries in the three phase requirement but not the single phase.
See the 705.2 Hybrid System def.
 

david luchini

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Connecticut
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So can three-phase systems be hybrid?

Yes, hybrid systems can be 3 phase. I think 705.100 is saying don't connect a single phase inverter from a pv system and windturbine system (for example) to a 3 phase system, because of unbalance.

If the hybrid system had 3-phase inverters for PV and Windturbine, unbalance wouldn't be a concern.
 

erickench

Senior Member
Location
Brooklyn, NY
NEC 705.82 permits hybrid systems to be interconnected with utility-interactive inverters. Is there any other way that hybrid systems can be interconnected?
 

tortuga

Code Historian
Location
Oregon
Occupation
Electrical Design
Are you planing a specific system? I think if the generation equipment is listed for the purpose (705.4), complies with its article (705.3) and the other conditions of 705 are met like 705.14 and 705.16 it would be fine co interconnect as per the mfr's instructions without an inverter.
 

erickench

Senior Member
Location
Brooklyn, NY
I'm preparing a powerpoint presentation for PE's continuing education. I shouldn't have asked that last question because hybrid systems use generators as power sources which can be AC and would not need an inverter. What's confusing me now is the definition of an electric power production source. NEC 705.2 give's the definition of hybrid systems and states that electric power production sources are not used as power sources for such systems. But NEC 705.1 seems to imply that a primary source being a utility is different from an electric power production source. What is an electric power production source if it's not a utility or any of the sources listed in the definition of Hybrid systems in NEC 705.2?
 

tortuga

Code Historian
Location
Oregon
Occupation
Electrical Design
What is an electric power production source if it's not a utility or any of the sources listed in the definition of Hybrid systems in NEC 705.2?
None.
The NEC article 100 definition of "Electric power production and Distribution Network" leads me to think they are including all non utility owned sources of electricity.
I wonder the if the NEC would apply to a facility with enough wind, Solar, biomass or whatever when that is there only business and they are a Qualifying Facility (QFs) under FERC? 90.2(B)(5)
 
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erickench

Senior Member
Location
Brooklyn, NY
I'm still confused on what the difference is between an electric power production source and a primary source. The FPN in NEC 705.1 cites examples of primary power sources as a utility supply or on-site electric power source. NEC 100 state's that Electric Power Production Sources are electric utility systems. What does what in an interconnected power system and how do hybrid systems fit into all this? How could a hybrid power source be used as a primary? Is the electric power power production source a back-up?
 
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