I don't know yet exactly what model of generator this is. Is it a "common" thing across lots of generator models to provide a relay output which is closed when the generator is running? If that's widely available on many generators then that will be very useful.
Most installations will offer some form of run indication, and more often than not you can get indication of auxilliaries on changeover contactors. Most of the new installs use a PLC so you can get any output you desire (specify and pay for).
The liason involved with getting a status contact can be a marathon however.
All too often
- The provided run contact has been monopolised by other systems.
- A status contact for Automation has been forgotten and the contractor wants mega-bucks to program one.
- The logistic of cabling within Form-3 or HV switchboards can cost a fortune to be done ina safe and compliant manner.
What I was just going to do anyway was to use a 5V switchmode power supply connected to the 240VAC power output from the generator, and simply watch that with the microcontroller.
That or an appropriate voltage relay. However the same gotchas as above apply in finding the appropriate point of connection. Wiring in without voiding warrantee etc.
A reliable contact is a always going to be the best indication. But the microphone option offers a great (and assumadly very reliable) alternative solution that can be installed without reference to other parties. A great lateral solution, particularly with a freetronics board now available off the shelf.