Electricity Metering and Control

[sprdave]

I was wondering about the possibility and what would be required to do the following setup, a little more tricky than typical.
We have 2 'services' (Enter the same shop side by side) from the same pole transformer (so same system);
Farm: 400A 120/240v single phase (2 x 200A wire) - splits to 3 100A switches/panels
Solar: 100A 240v single phase

We would like to measure the watts (KW) of each service. Then we want to add (compare) the two, and if the difference is like 2Kw (solar producing more than farm is using) then close a relay output. Then when it drops below 0Kw either open the first relay output (if it stays closed when it drops below 2Kw) or operate a second relay.
Any possibilities?

The trick is combining the two services and then using that value for an output. Basically we want to use excess power from the solar system for optional load(s).

 

[tmbrown97]

have you checked out the brultech products? I don't have first hand experience with them but based on what I've read they should help you do exactly what you're after.

http://www.brultech.com/products/ECM1240/default.htm

 

[will40]

I was wondering about the possibility and what would be required to do the following setup, a little more tricky than typical.
We have 2 'services' (Enter the same shop side by side) from the same pole transformer (so same system);
Farm: 400A 120/240v single phase (2 x 200A wire) - splits to 3 100A switches/panels
Solar: 100A 240v single phase

We would like to measure the watts (KW) of each service. Then we want to add (compare) the two, and if the difference is like 2Kw (solar producing more than farm is using) then close a relay output. Then when it drops below 0Kw either open the first relay output (if it stays closed when it drops below 2Kw) or operate a second relay.
Any possibilities?

The trick is combining the two services and then using that value for an output. Basically we want to use excess power from the solar system for optional load(s).

If you are just looking to monitor loads with the capability of having a relay contact open or close on a predetermined setpoint then you could cobble together a hard wired circuit using CR Magnetics current sensing relays.

I believe the largest sensor relay unit is rated for 100A.

See http://www.crmagnetics.com/products/Assets/ProductPDFs/4395_a.pdf for some specs.

I Hope it helps.

 

[sprdave]

have you checked out the brultech products? I don't have first hand experience with them but based on what I've read they should help you do exactly what you're after.

I was looking at Brultech a bit, which looks good for monitoring (other than having to use a computer), but is there a way to output to a relay based on certain parameters?

I'll look at those CR Magnetics relays. Im wondering since I cant seem to find anything multi-channel that will also control a relay, about building my own something....like if I run all the CT wires from all the panels together through a sensing relay, they would cancel each other out and if there was a significant current left than operate the relay...just thinking here.

 

[BraveSirRobbin]

I guess I'm not really sure what you are trying to accomplish. Are you feeding the solar system 'into' the grid currently? I guess I'm not seeing how you are currently using the solar feed and how you switch between regular power and solar power.

Also, are you wanting to use the solar feed to 'other' loads not in your current feeds IF the regular power feed input is not being utilized (i.e. drawing little current)?