Switzer Instrument Ltd, Chennai,
has introduced the most
advanced electronic digital
pressure switch for the Indian market.
SWITZER Model 711 electronic
pressure switch is a versatile
electronic instrument matching with
contemporary designs with all the
fundamentally required features for
basic control functions.
The instrument is provided with LCD
indication, two independent set point
On-Off control relay outputs and
analog output of 4 to 20mA.
Operational settings are done through
three keys on the front keypad.
The stainless steel pressure sensor and
wetted parts are compatible for both
liquids and gases. Two relay switching
outputs, with independent time delay
settings, have status indication LEDs on
front of the instrument. Both set-point
and dead-band can be set throughout
the calibrated range.
The instrument is weatherproof to
IP65 and operates with DC power
supply. The external electrical
connections are through two polarized
and lockable plug-in connectors.
The primary pressure sensing element
for the detection is a stainless steel
diaphragm on which piezo-resistive
elements are configured in a bridge form.
When the diaphragm is subjected to a
pressure, the stress produces a
strain on the deposited bridge to give an
electrical output when excited. The
sensor is temperature compensated to
ensure minimal drift with ambient and
process temperature changes.
The sensor output signal is suitably
conditioned to generate the
necessary signal and is fed to a
A-to-D convertor to convert it
to digital signal compatible to a
micro-controller.
This digital signal is processed to
provide output for process pressure
display on LCD, output to relay for onoff
control and output as 4-20mA
analog current.
The key features of the product are:
- Pressure range from 0 to 1 bar to
350 bar
- Piezo-resistive stainless steel pressure
sensor
- Accuracy of +/-0.3% of full scale
- Operating power of 20 to 30VDC
- Display of 1x8 dot matrix LCD with
yellow green backlight
- Choice of 5 units - bar, psi, Kg/sq.cm,
KPa, MPa
- Analog transmitter output of 4 to
20mA
- 2 set-points are provided with
independent on-off relay contacts
- Time delay option up to 250 secs