Technical

AC current sensor explanation3(Frequency characteristic and Ratio error and phase shift)

Frequency characteristic

The data written in the catalogue is expressed as the premise of use with commercial frequency (50/60Hz) basically.
Theoretically, the flux density of the core is inverse proportion, the characteristic as CT has the direction to be worth with below 50Hz and better with high frequency.
However, there is the limitation of the other parameters, because higher frequency makes more loss of the core, and resonance phenomena of coil.
Thus, the specification should be decided with enough check of the using condition.
[Figure.9] is the frequency characteristics of CTL-6-P-H as the pilot product.

Ratio error and phase shift

·Ratio error……(Accuracy of current)
It is the ratio of the error between the ideal value and actual value in each measuring point.
Although the expressing method is different, the coupling efficiency (K) characteristics can be defined as the expression of this ratio error characteristic in a sense. The calibration of ratio error can be done with optimizing the load resistor.

·Phase angle……(Accuracy of waveform)
It is the phase shift of output waveform toward original measured waveform.
Output of CT becomes usually leading phase.

These two characteristics are the important factor for the CT of power measurement, especially. There is JIS standard for the CT of meter application as 1A-5A output which is used usually. However, the current sensor of URD can't be applied to the JIS standard, because the other parameters such as load resistor need to be thought with the cause of the high current ratio, although the principle is same.

The better ratio error and phase angle can be gotten with more turns and bigger cross section of the core, or CTL-Z series rather than CTL series for general purpose, as the trend.
[Table.2] , [Figure.10] , and [Figure.11] are the characteristic of the pilot products.

Ratio error and phase angle of pilot current sensor
(f=50Hz,RL=100Ω) measured by JEMIC