VEGA VEGASWING 83 fail safe and signal conditioning instrument VEGATOR 526 Ex - Manual (Page 3)

VEGASWING 81 W5 Ex.C, 83 W5 Ex.C fail safe 3
Product description
1 Product description
1.1 Function and configuration
VEGASWING 81␣ W5␣ Ex.C and 83␣ W5␣ Ex.C fail
safe vibrating level switches detect levels of
liquids with a viscosity of 0,2 mPa␣ s to
10.000␣ mPa␣ s and a density
≥
␣ 0,5␣ g/cm 3 . The
modular construction enables the use in
vessels, tanks and pipelines. Typical
applications are overfill protections according
to AK5.
Due to the simple and rugged measuring
system, VEGASWING can be used virtually
unaffected by the chemical and physical
features of the liquid. It operates also under
arduous conditions such as turbulences, air
bubbles, foam generation, build-up and
changing medium.
With the mechanical connections thread and
flange, VEGASWING 81␣ W5␣ Ex.C or
83␣ W5␣ Ex.C can be used in manifold
applications.
For the use in very aggressive products,
Hastelloy C4 and ECTFE (halar), Säkaphen
and enamel-coatings are used for
VEGASWING 81 and 83.
VEGASWING 83 F… can be coated with
enamel or up to 1200 mm and Säkaphen up to
4␣ m tube length.
For medium temperatures of more than 100
°
C
to 130
°
C VEGASWING 81␣ W5␣ Ex.C and
83␣ W5␣ Ex.C must be equipped with a
temperature adapter.
Function
The tuning fork is piezoelectrically energized
and vibrates at a resonance frequency of
approx. 400␣ Hz. A second piezoelectrical
element measures the resonance frequency of
the tuning fork. When the tuning fork is
covered with the medium, the resonance
frequency changes. This frequency change is
continuously detected by the integral oscillator
and converted into a switching command by
the connected signal conditioning instrument.
With a mode switch you can determine the
switching mode (overfill protection or
protection against dry running of pumps).
Note that VEGASWING 8…␣ W␣ Ex.C only meets
the fail safe requirements in mode A (overfill
protection).
Fail safe / Self-monitoring
A special feature of this instrument
configuration VEGATOR 526␣ Ex with
VEGASWING 81␣ W5␣ Ex.C or 83␣ W5␣ Ex.C is the
integral self-monitoring. It is based on a red-
undant microcomputer system in the signal
conditioning instrument and includes the
complete measuring chain from the tuning fork
via the oscillator, the two-wire line as well as
the signal conditioning instrument (see also
“1.3 Recurring test acc. to WHG“).
The self-monitoring includes two routines:
- the permanent monitoring
- the cyclical self-test.
During the permanent monitoring the signal
conditioning instrument induces the oscillator
of the sensor to carry out a test cycle in
960␣ msec-cycle. Hence defined test signals
are transmitted via the two-wire line to the
signal conditioning instrument. Probable errors
in the sensor electronics as well as line break,
shortcircuit and mechanical damages on the
fork are signalled via these test signals.