815212302 datasheet(4/28 Pages) MAGNETROL

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50-605 Kotron RF Point Model 80/81 Level Switches

1.0

Introduction

1.1

Principle of Operation

The amount of capacitance developed in any vessel is

determined by the size (surface area) of the probe, the dis-

tance from the probe to its ground, and the dielectric of

the medium being measured. Considering that the probe’s

mounting position is fixed, and that the dielectric value of

the medium is constant, then the amount of capacitance

developed in any vessel becomes dependent upon the

probe’s total surface area.

A probe’s diameter, together with its length, determine its

surface area. Adjusting the combination of probe diameter,

length, and proximity to ground, the necessary capacitance

required by the electronic circuitry can generate.

As media rises and falls in the tank, the amount of capaci-

tance developed between the sensing probe and the ground

also rises and falls. This change in capacitance is sensed by

the electronics.

The capacitance-controlled oscillator circuit, mounted

on the probe, changes the capacitance signal to a variable

frequency. This stabilized signal can then be sent to the

main electronics located up to 5000 feet (1500 meters)

away via standard shielded, twisted pair cable. This

eliminates the 150 feet (45 meters) maximum distance

limitation, using costly coaxial or triaxial cable utilized

by other manufacturers.

1.2

Description

Kotron RF Point Level Switchescan be utilized in level

control applications with either liquid or dry bulk materials.

They can also be used to sense and control viscous, sticky,

highly conductive materials. The electronic amplifier may

be either mounted directly on the sensing probe or located

remote from the probe. In remote applications, the sensing

probe is furnished with a housing.

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