Inverter switching times

[GCE]

HI

I have been having discussions around inverter switching times after a mains failure.
I can find no regulation that prevents me from bringing an inverter on line 0,1sec after the mains has failed - I presently have a supplier saying that it must be 0,25sec.

Have looked through SANS and Nersa documents - I can only find reference to synchronizing with the grid , which cannot happen until the a period of stabilization has happened for 60 seconds .

Has anybody come across a regulation stipulating switching times ?

[Rifrug]

Hi GCE
I have not seen any regulation that states 0.25s switching time. It is possible that such a regulation exist on the COCT for grid tied inverters, so that the meter can pickup a feed to grid and disconnect the solar immediately when grid is switched off. The reason being you cannot feed to the grid as it will pose a danger to the Eskom or municipal workers that is doing maintenance on the grid. As far as I know if your system is off-grid this would not effect any workers as the off grid system is isolated from grid supply.

[Justloadit]

UPSs advertise switching times of 10mSecs or a half cycle reaction time. The switching times has nothing to do with the grid, simply because at this time the load would have been disconnected from the mains.

It may be the specific inverter referred to, may have an inherent reaction time of 250mSecs, and this is to allow the Sine Wave inverter to start up and get up to speed voltage wise. Usually the sine wave generation is dormant when not required to reduce operational time in the electronics, which require forced cooling when running, prolonging Fan lifespan and reduction of sucked up dust being cast on the cooling fins..

[GCE]

Thanks Justloadit

The explanation on the electronics and fan makes sense as they offer a 10 year warranty on the unit, which then makes sense .