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 ?