50-660 Kotron
®
Model 805 Smart RF Level Transmitter
19
3.0
Reference Information
This section presents an overview of the operation of the
KOTRON Model 805 transmitter, information on trou-
bleshooting common problems, listings of agency
approvals, lists of replacement and recommended spare
parts, and detailed physical, functional, and performance
specifications.
3.1
Description
Model 805 is a two wire, 24 VDC, level transmitter based
on the concept of RF Capacitance.
The Model 805 electronics are housed in an ergonomic
housing comprised of two tandem compartments angled at
45 degrees for ease of wiring and calibration. These two
compartments connect via an explosion-proof and water-
tight feed-through.
3.2
Theory of Operation
RF capacitance electronic level measurement utilizes the
same fundamentals as any electronic capacitor (Figure A).
A capacitor is formed when an AC signal is applied across
two conductive plates separated by an insulating medium,
or dielectric. The value of a capacitor is determined by the:
1. Area of the conductive plates (A);
2. Distance between the plates (D), and;
3. Dielectric of the insulating medium between the
plates (E). Refer to Figure A.
Capacitance = EA/D
(The AC frequency is fixed as part of the design.)
Current Meter
+
–
Test
Current Meter
Power Supply
24 Vdc
+
–
Conductive
Plate
Conductive
Plate
Insulating
Medium
AC
Figure A
