Determining if Generator is running.

[Big517]

I'll admit i'm not sure what would apply to me, the 120 or 220...  I have the 20KW generator and it will power everything on my 200amp service panel.  I remember it works initially with a load balance where it would fire up my first HVAC system, then my 2nd afterward if both are calling to run, but I am not sure if that is relevant...  
 
I would prefer NOT to run these in series with the Fault output simply because I will monitor that separately.  I simply need to know when the Generator is running power.
 
I certainly appreciate your insight and helpfulness, I hope I've provided enough info...   If not, PM me, and we can chat on the phone.
 
Thanks again.

 

[BraveSirRobbin]

Here is a schematic using two 120 VAC coil relays in series.  If one or both legs open, a fault will be detected.  The zone should be normally closed with EOL defeated.  If you wanted to use an EOL resistor, place it 'in line' with one of the relay terminals.
 
As I recommended in an earlier post, if this is mission critical (i.e. you HAVE to know if this device is running) I would highly recommend monitoring the current as I show in the second half of the attached schematic.  This way, if on generator or line power, you will know that the device is indeed running (you would set the threshold current needed to give a contact closure from that current donut, then just run that contact closure to an Elk zone).
 
View attachment GenMonitoring - Copy.pdf
 
Remember, you can have 'voltage' appearing on your relay monitors, but this does not tell you if you had a proper transfer of the power to the device.  I've seen some weird things happen with transfer switches during power failures in the field.
 
If you have any questions please ask.
 
Also, I'm sure if there is a better way of doing this, our forum membership will chime in (as that is always welcome)!
 
 

 

[RAL]

BSR - I think an issue that needs to be addressed in your schematic is how to provide over current protection for the relays.
 
The generator has a circuit breaker on it, but it would be something on the order of an 80A breaker for a 20kW generator.  In order to wire up the relay coils with a reasonable gauge wire (say 14-2), I think the electrical code will require that they be protected by a correspondingly sized breaker or fuse.  And that leads to the next question of where the best place to locate these is.  
 
This makes me think that your earlier suggestion of using a current transformer/relay on the output of the generator might be a simpler approach.

 

[BraveSirRobbin]

Yea, good point.  He could just wire in an in-line fuse holder between the L1 and L2 lines and the relays though and put that right next to those terminals (as shown below).  Most likely a one or two amp would work, depending on the coil resistance of the relay chosen.