Frequently Asked

Why is the CT not showing zero's when the CT is not connected

Reading values with the CT unconnected will output a small value. This is normal.

The CT sensor is an analog sensor and has noise. i.e. It will always measure an approximate value. Hence zero + noise when not connected.

Even if nothing is connected there will be always a tiny current running in the burden resistor inducing a small voltage. In turn this will convert into a small power. For a board setup for the SCT-013-000 with 100A fitted burden resistor one might find a background noise under 100W.

If the admitted noise value appears too high then one might have to opt for lower range burden resistor.

I can not read anything once the CT is clamped

Make sure the SCT is clamped around A SINGLE PHASE.

Clamping the SCT on the whole cable will never read anything as it measures two currents. One positive minus plus one negative which sums to 0 (or 0 + noise).

The easiest for a quick test is to connect the SCT at the meter level on a single phase. Otherwise if you wish to measure the power used by a single application then one should make a special cable that split phases.