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Section 1: Introduction
1.1
System Description
d
d
A
A
k
C
C
air
k
media
k A
k A
C =
C =
d
Figure 1-1
Simple Capacitance Probe
(Insulating Media Shown)
1.2
Technology
Figure 1-2
RF Admittance Probe
with Cote-Shield
Installation of the AMETEK Drexelbrook IntelliPoint
Series Products is simple and easy. Simply apply power and
IntelliPoint system is ready to detect the presence or absence
of material. Since IntelliPoint instrument does not require
calibration or setpoint adjustments, it is capable of operating in
k
non-dedicated tanks regardless of the material being measured.
air
Notice: Material to be Measured Must Be Below
Sensor when Power is Applied.
k
media
The AutoVerify™ self-testing function continuously monitors
the entire system to ensure proper operation. Manual
Certify™ changes the outputs in order to test the loop current
and ensure proper operation of the control systems.
d
In a simple capacitance probe-type sensing element, when
the level rises and material covers the probe, the capacitance
within the circuit between the probe and the media (conductive
applications) or the probe and the vessel wall (insulating
applications) increases. This is due to the dielectric constant
(k) of the material, which causes a bridge mis-balance. The
signal is demodulated (rectified), amplified, and the output is
increased. There are drawbacks, however, especially when
there is coating of the probe.
An RF Admittance level transmitter is the next generation.
Although similar to the capacitance concept, IntelliPoint
employs a radio frequency signal and adds the Cote-Shield™
circuitry within the Electronics Unit.
This patented Cote-Shield™ circuitry is designed into the
IntelliPoint series and enables the instrument to ignore the
effect of buildup or material coating on the sensing element. The
sensing element is mounted in the vessel and provides a change
in RF admittance indicating presence or absence of material.
The Cote-Shield element of the sensor prevents the
transmission of RF current through the coating on the sensing
element. The only path to ground available for the RF current
is through the material being measured.
The result is an accurate measurement regardless of the amount
of coating on the probe, making it by far the most versatile
technology. It is suitable for very wide range conditions and
materials from cryogenics to high temperature, from vacuum
to 10,000psi pressure.
1
Introduction
™
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