tlc2-manual-01
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Operating Principle
C(air)=
ε
(air) x P x (H-L)
C(material)=
ε
(material) x P x L
C(residual) is due to device itself.
Where
ε
(air) is the dielectric constant of air
≈
1.
ε
(material) is dielectric constant of material.
P is the constant of probe and installation, H is the active length of probe and L is the level of material.
Capacitance to level translation is performed with the aid of on-site calibration also called "wet-calibration".
The probe forms a capacitance with the metalic tank-wall.
The capacitance is sum of three capacitance:-
4
20
mili-Ampere
L(low)
Level
L(high)
The device stores a low level capacitance as level for 4mA and high level capacitance as level for 20mA
as defined by the user.
Using these values and following equation
C(high) C(low)
L(high) L(low) =
P x {
ε
(material)
ε
(air)}
device creates a chart of level to 4-20mA translation.
C(residual)
C(material)
CALIB
4 20
read C(low)
for 4mA
mA
CALIB
4 20
read C(high)
for 20mA
mA
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