Disconnection times with off grid application.

[MRL]

Hi All
New to this forum and fairly new to the business too.

I have a project I'm putting together which is an off grid house. There are two 5000VA inverters with sufficient battery size and a sizeable generator to switch in once loads exceed about 7kW, which will ADD a further 100A.

Here's my conundrum, but could be just numb brain. If the system is running on inverters only it can deliver a maximum of 10kVA/230V = 43A. The inverters will operate at 100% overload for 30 mins before shutting down, so the maximum fault current that can be delivered would be 2 x 43A = 86A. Every final circuit and the distribution is RCD protected but for overcurrent protection does such a low Ipf mean that MCBs above 16A will not achieve disconnection within the required time? Obviously such a demand would cause the genny to start and add current but the time this would take would be indeterminate.

Is setting all of the MCBs to 16A the answer, although it contravenes 433.1.1 (i) for some loads such as cooker and water heater.

Thanks

 

[Selfmade]

I'm thinking aloud here and may also just have a numb brain, but since nobody else has replied here goes: is 86A definitely the Ipf, or is that just the maximum current the inverter can handle safely, with the Ipf being much higher? Maybe something to think/read about, but don't just assume I'm right - I may be very wrong!