Cls300 Electrode - Siemens Pointek CLS200 Operating Instructions Manual

A.6

CLS300 electrode

The Pointek CLS300 electrode is the primary sensor of the system. It supplies the electrical
capacitance value.
The Pointek CLS300 patented Active Shield Technology electrically isolates the measurement
section and reduces the effect of any non-measurement capacitance on the measurement
capacitance. (Capacitance changes could result from uncontrolled variations occurring in the
connection cable, process connection, and non-active parts of the probe.) This gives a better
ratio of initial capacitance to total capacitance, resulting in higher accuracy.
R = Ratio between initial capacitance and total capacitance
Ca = Initial capacitance (air)
Cm = Capacitance Increase (product)
C1 = Capacitance connection point
C2 = Capacitance connection cable
C3 = Capacitance Process connection (includes active part)
Pointek CLS300 with active shield
R = Ca/(Ca + Cm)
① Measuring circuit
The measurement is further protected from interference by a buffer, which applies the
frequency signal from the measurement section to the Active Shield section. This effectively
eliminates any electrical potential difference between the shield and the measurement
section and prevents additional changes in capacitance occurring, especially when material
builds up at the probe entrance to the tank.
Pointek CLS200/CLS300 digital
Operating Instructions, 05/2021, A5E47904060-AA
Conventional capacitance measurement
R = ((C1 + C2 + C3) + Ca) /((C1 + C2 + C3) +
Ca + Cm)
Technical reference
A.6 CLS300 electrode
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