Capacitance Level Probe
Principal of Operation:
The level measurement of a medium in a tank, as shown to the right, is accomplished by taking advantage of the capacitance theory. The tank wall, the probe and the medium are all capacitors. A high fre- quency sine wave is then applied between the probe and the tank wall. The level change of the medium will consequently change the current of the applied sine wave.
From the formula Z=1/(2 fc), we know that if the capacitance increases, the impedance gets smaller and the current gets bigger. If the ca- pacitance decreases, the impedance gets bigger and the current gets smaller. When the small current change is amplified and sent to a PM-50, the output signal is 0/4-20mA or 0-10VDC.
APPLICATIONS AND FEATURES
1. The system works ideally in high temperatures, high pressure, acid and alkaline environments. It is also works well with
2. It will not be affected by steam, sound waves, tension and changes of temp. It is suitable for variety of industries and environments, including powder, granules, liquid applications in mines, food, chemical and petrochemical industries.
3. The signal input and output are optically isolated. The system is insulated from surge or lightning damage.
4. The MEC-10 Type is suitable for nonconductive materials which can not be exposed to moisture such devices used in powder silo.
5. The MEC-20 Type is suitable for nonconductive materials such as those used in edible oils.
6. The MEC-30 Type is suitable for nonconductive materials such as those used in oil-tank environments.
7. The MEC-40 Type is suitable for conductive materials such as those used in small-sized, corrosive liquid tank environments.
8. The MEC-53 is suitable for conductive materials such as those used in water-tank envi- ronments.