I recently improved a personal project I undertook while in the University. It's an Automatic changeover switch that can switch off the generator aswell.
I used contactors and relay to design and construct this ATS.
What made me think about this project again was a particular football viewing centre and betting shop in my area that has the challenge of switching over to NEPA manually when power is restored. This always causes protest and agitation among football lovers who get angry when the owner of the viewing centre decides to switch from generator to NEPA while a match is ongoing. The time taken for Dstv to restart and others delays is the cause of this protest.
And for the betting shop, those who play virtuals and those booking and betting games from desktops that have no UPS, have to start afresh when the shop owner switches back to NEPA...
With this my design, the change over will be in milliseconds, and it will be done automatically with no human input. Nothing will be Disturbed .

so, my question is how can I sale this idea to many betshops including the one I talked about.

I need words to say,
how to present this idea to my potential client?
and the best time to approach this client?

I thought about this same thing yesterday and wondered if there is any thing to make that Possible. Look for just a client and do a Practical work of the Project. As far as it works, you will make great sales and referrals will come in too.
Goodluck with your Project, I hope to hear goodnews as I will be following the thread.