What are these?

[Ray Thornburg]

Does anyone know what these are?

[Jim Port]

Look like CTs for energy measurement systems or metering.

[Jerry Peck]

Look like CTs for energy measurement systems or metering.

For those who don't know, CT stands for 'current transformer'.

When current flows through a conductor a magnetic field is created around the conductor. When that current is ac current, the magnetic field expands and contracts with the ac voltage sine wave.

That expanding and collapsing electromagnetic field generated current flow through a conductor placed within that magnetic field. The CTs are simply coils which generate ac voltage and current at their leads when ac current flows through the conductor run through the current transformer. The CTs are calibrated (the are manufactured to create a given current and voltage based on the magnetic field, which is directly related to the current in the conductor.

Thus, for a given current through the conductor, a known current and voltage will be generated by the CT, and that known current and voltage can be used for metering, for monitoring the current flow and overcurrent devices, and for other things.

[Ray Thornburg]

Thanks......So who or what could be using these to measure the current?

[Jerry Peck]

Thanks......So who or what could be using these to measure the current?

The power company may have installed a CT meter, it works the same as a regular power meter except that the calibration is different (instead of 200 amps running through the sensor there may only be a few amps, depending on the CTs and the meter calibration.

I have not done much with CT meters, so I am sure there are others here who can expand on what I have posted, and even correct me where I am totally wrong (likely the amount of current from the CT).

[Jim Port]

Might be part of a system like this.

TED 5000 (http://www.theenergydetective.com/ted-5000)

Lets users see how much power is being used and where.

[Benjamin Thompson]

Might be part of a system like this.

TED 5000 (http://www.theenergydetective.com/ted-5000)

Lets users see how much power is being used and where.
Or may be part of a load controller system.

[Ray Thornburg]

Thanks guys......

[Stephen G]

So, they are located in the panel on the hots. If so, then its another meter? Its pretty much always going to read somehting isnt it..?
Asking outloud...



For those who don't know, CT stands for 'current transformer'.

When current flows through a conductor a magnetic field is created around the conductor. When that current is ac current, the magnetic field expands and contracts with the ac voltage sine wave.

That expanding and collapsing electromagnetic field generated current flow through a conductor placed within that magnetic field. The CTs are simply coils which generate ac voltage and current at their leads when ac current flows through the conductor run through the current transformer. The CTs are calibrated (the are manufactured to create a given current and voltage based on the magnetic field, which is directly related to the current in the conductor.

Thus, for a given current through the conductor, a known current and voltage will be generated by the CT, and that known current and voltage can be used for metering, for monitoring the current flow and overcurrent devices, and for other things.