The SLA series of admittance based level
switches are designed to offer interference free
signal transmission from the electronic insert
to the evaluation unit. This level control has no
moving parts, no mechanical wear and tear and
offers added reliability in form of system fault
detection. One can , calibrate the system from a
remote location and the evaluation unit can be
installed away from the the probe. The
calibration controls are available in the
evaluation unit.
The SLA admittance level sensor has a fail-safe
high/low Selection feature available as a
standard. This helps in reducing inventory since
the same evaluation unit can be field-configured
either for high or low level fail-safe
detection. The system ignores the built-up of
sticky and conductive material between the probe
and the vessel walls. The system is based on a
3-electrode technique with coat-immunizing
circuitry to create inactive region. The system
is economic to install and uses ordinary 3-Core
cable for interconnecting the electronic insert
with the evaluation unit.
Applications
The SLA series of level
instruments works well with a
range of serive materials such
as fine, coarse, solids, liquids
and slurries, conductive or
non-conductive, corrosive or
non-corrosive that have a tendency to stick and coat. The
system can be used to switch off
conveyors when the
vessel is full to avoid
overflow. A major application is
for indicating an empty tank
well in time to avoid production
stoppage and for pump control.
Our customers have successfully
used the SLA series of level
indicators and controls in the
Cement, Food, Chemicals,
Fertilizer, Sugar, Cosmetics,
Detergent and many other
industries.
Measuring System
The SLA series consists of an
evaluation unit, an electronic
insert and a probe. The probe is
mounted either from top or side
of the vessel. The probe
comprises sense and shield
electrodes electrically isolated
from the metallic tank by means
of insulators. The sense
electrode and the vessel wall
serve as the two electrodes of
an imperfect capacitor with the
service material as the
dielectric. A change in material
level causes a change in
admittance of this tank
capacitor. An accurate
measurement of this change
affords an indirect measure of
the level of material in the
tank. The electronic insert
measures the change of
admittance accurately by using
Radio Frequency (R.F.) technique
coupled to a DC voltage
variation, which is transmitted
to the evaluation unit via
3-core unscreened cable for
further processing. The
processed signal is used to
energize or
de-energize a relay whose output
contacts are available for
annunciation or control.
Technical
Data
Electronic
Insert - ICA
3000
Housing
:
Plastic
, potted
in epoxy
resin.
Measuring
Frequency
~ 500
KHz.
Ambient
Temp.
: -20º C
to + 80º
C.
Supply
Voltage
: 15 V
derived
from
evaluation
unit.
Output
Signal
: 3 to
12 V DC.
Evaluation
Unit
Housing
: Cast
Aluminum,
Weather
proof,
back
panel/wall
mounting
Cable
Entry
: 3 Nos.
Max.
Amb.
Temp.
: - 20º
C to +
60º C.
Power
Consumption
: 5 VA
approx.
Mains
Voltage
: 230 V
or 110 V
AC (-15%
to
+10%),
50 Hz;
24V
AC/DC on
request
(to be
specified
while
ordering).
Relay
Output
:
One/two
sets of
potential
free
change
over
contacts
rated at
230V AC
6A, 50
Hz for
non-inductive
loads
per
set
point.
Fail
Safe
Mode
: Max.
or Min.
Field
selectable.
Indication
Red LED
for
alarm,
Green
LED for
normal,
Yellow
LED for
system
fault.
Indication
: Red
LED for
alarm,
Green
LED for
normal.
Response
Time
: 0.2
Second
Switching
Delay
for SLA
322/622/
822/922
:
Adjustable
from 0.5
to 20
Second.
for
probe
covered
or
uncovered.
Admittance
Level Limit Switch (SLA Series)
