CT's/Sensors - How they work?

The Current Transformers (CT's) are the sensors used by the Gen 2 to measure power in real-time. They're filled with a magnetic material called Ferrite that contains special properties that allow us to measure the current flowing through a circuit line or wire. They're split-core, meaning they snap apart at the sensor itself, so they can be clamped directly around the circuit line without requiring you to detach the circuit line or any electrical work.

The "200A" CT's designed to be placed on the system main lines will measure up to 250A on the Gen 2 top ports - the "50A" CT's will measure up to 75A. If that amperage/current limitation is passed, no damage will occur to either the Gen 2 device or the sensors since they're passively monitoring power, but the measurements will max out at those amounts respectively. One important note, the amperage limitation itself is not on the sensor but on the Gen 2 device port. That means that using a 200A CT on a Gen 2 side port (designed for the 50A CT's) will still only reach 75A before maxing out its measurement capacity.

How many 200A CT's are needed?

Depends on the phase count in your system. One 200A CT sensor per phase/live main line. (neutral and/or ground not included as a "phase")

Can I use a 200A CT on a side port?

Yes - you will need a 3.5mm to 2.5mm audio adapter for the different jack size (to fit the device port) and a 4.0 multiplier on the circuit to adjust for the different sensor size calibrations. Note - will still have a 75A limitation on the circuit (rather than 200A).

Can I use a 50A CT on a top port?

Yes - you will need a 2.5mm to 3.5mm audio adapter for the different jack size (to fit into the device port) and a 0.25 multiplier on the circuit to adjust for the different sensor size calibrations.

Related Articles:

- CT not showing up in circuit list
- Troubleshooting CT Accuracy
- More than 16x circuit lines to monitor?

Feedback and Suggestions

This knowledge base is pretty new for the Emporia team. Our goal is to provide all of the information we can to help you manage your energy in better ways. If this article wasn't helpful, or we could be more clarifying on any points please reach out to the Customer Support team and we'll certainly work to improve these guides.