Principle Of Operation; Operation - Siemens SITRANS LVL200E Instruction Manual

3 Product description
Application area
Functional principle
Voltage supply
8

3.2 Principle of operation

SITRANS LVL200E is a point level sensor with tuning fork for level
detection.
It is designed for industrial use in all areas of process technology and
can be used in liquids.
Typical applications are overfill and dry run protection. The small
tuning fork allows use in all kinds of tanks and vessels. Thanks to its
simple and rugged measuring system, SITRANS LVL200E is virtually
unaffected by the chemical and physical properties of the liquid.
It functions even under difficult conditions such as turbulence, air
bubbles, foam generation, buildup, strong external vibration or
changing products.
Fault monitoring
The electronics module of SITRANS LVL200E continuously monitors
via frequency evaluation the following criteria:
Strong corrosion or damage on the tuning fork
l
Loss of vibration
l
Line break to the piezo drive
l
If a malfunction is detected or in case of power failure, the electronics
takes on a defined switching condition, i.e. the contactless electronic
switch opens (safe condition).
The tuning fork is piezoelectrically energised and vibrates at its
mechanical resonance frequency of approx. 1200 Hz. The piezos are
fixed mechanically and are hence not subject to temperature shock
limitations. The frequency changes when the tuning fork is covered by
the medium. This change is detected by the integrated electronics
module and converted into a switching command.
SITRANS LVL200E is a compact instrument, i.e. it can be operated
without external evaluation system. The integrated electronics
evaluates the level signal and outputs a switching signal. With this
switching signal, a connected device can be operated directly (e.g. a
warning system, a PLC, a pump etc.).
The data for power supply are specified in chapter "Technical data".

3.3 Operation

With the factory setting, products with a density > 0.07 g/cm³
(0.025 lbs/in³) can be measured. The instrument can be adapted if
products with lower density should be measured.
On the electronics module you will find the following indicating and
adjustment elements:
Signal lamp for indication of the switching condition (green/red)
l
DIL switch for sensitivity adjustment
l
Mode adjustment for selection of the switching condition (A/B)
l
SITRANS LVL200E - CONTACTLESS ELECTRONIC SWITCH