Frequently Asked: Difference between revisions
| Line 2: | Line 2: | ||
==Why is the CT not showing zero's when the CT is not connected== | ==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. | Reading values with the CT unconnected will output a small value. This is normal. | ||
The CT sensor is an analog sensor and | 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. | 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 noise value | 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== | ==I can not read anything once the CT is clamped== | ||
Revision as of 07:35, 12 October 2017
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.