Automatic generator start

Andre,

The simplist verson of monitoring mains voltage is a relay with a 380V coil, and a normally closed secondary. This would open on power failure, and the RPI can start the generator (assuming an electronic ignition).

Please remember to introduce a delay on start up and shut down - out of phase generator and mains electricity on grid restoration will blow everything up! This could be a 2 pole relay (phase and neutral) with a timed delay switching from mains to generator. This is where the UPS would come in.

In commercial installations, the critical load is driven by a UPS, with perhaps 20 minutes of autonomy. The UPS input would have 2 feeds, mains and a generator backup. In normal operation the mains charges the UPS and powers the Critical devices. When power fails, critical devices are supplied by the batteries, the supply changes over and the generator starts to charge the batteries. Some other supplies may be deemed necessary, which will be generator supplied, but 15 -20 seconds of generator start up is acceptable. On restoration of power the generator will shut down and mains power will switch over.

ATS (automatic transfer switches) are the commercial switching product, but a good quality relay / contactor with a delay would do.

Of course, if you are having brown outs, not just blackouts, that's a whole different thing. Then you are definitely into phase monitoring (I would reccomend a meter with Modbus, some have aux output contacts that can drive relays).

I hope that makes sense and helps!

Andre,

The simplist verson of monitoring mains voltage is a relay with a 380V coil, and a normally closed secondary. This would open on power failure, and the RPI can start the generator (assuming an electronic ignition).

Please remember to introduce a delay on start up and shut down - out of phase generator and mains electricity on grid restoration will blow everything up! This could be a 2 pole relay (phase and neutral) with a timed delay switching from mains to generator. This is where the UPS would come in.

In commercial installations, the critical load is driven by a UPS, with perhaps 20 minutes of autonomy. The UPS input would have 2 feeds, mains and a generator backup. In normal operation the mains charges the UPS and powers the Critical devices. When power fails, critical devices are supplied by the batteries, the supply changes over and the generator starts to charge the batteries. Some other supplies may be deemed necessary, which will be generator supplied, but 15 -20 seconds of generator start up is acceptable. On restoration of power the generator will shut down and mains power will switch over.

ATS (automatic transfer switches) are the commercial switching product, but a good quality relay / contactor with a delay would do.

Of course, if you are having brown outs, not just blackouts, that's a whole different thing. Then you are definitely into phase monitoring (I would reccomend a meter with Modbus, some have aux output contacts that can drive relays).

I hope that makes sense and helps!