The Industrial Thermometer of the Future...
Tel-Tru’s
DIGI-TEL Thermometers combine the easy, quick visual
reference feature of a local indicator and the precision
readout of a digital thermometer with a unique interchangeable
probe concept.
DIGI-TEL
battery powered models combine the easy, quick visual
reference feature of a local indicator and the precision
readout capability of a digital thermometer with a unique
interchangeable probe concept...
SELECT,
CONNECT, and INSTALL! DIGI-TEL
solar powered models are available with an integrated
cable and/or probe. All
DIGI-TEL models
have a one year warranty.
Local temperature indicators available without external power,
until now, have all been analog dial types, either filled
with mercury or gas, or of bimetal design. The new
DIGI-TEL
thermometer has been designed utilizing state-of-the-art
microprocessor technology, resulting in a more reliable,
flexible, and accurate alternative in temperature measurement.
The Tel-Tru solar powered
DIGI-TEL has
as its energy source a solar cell as an integral part
of the display module. The instrument functions reliably
in artificial light at levels above 50 lux. The 100-lux
minimum for many industrial plants means the installation
of the Tel-Tru solar powered
DIGI-TEL
can be used practically anywhere. The Tel-Tru battery
powered
DIGI-TEL uses a lithium battery,
which has a working life of five years.
Interchangeable
probe assemblies offer maximum flexibility for use in
industrial, test, and OEM applications. Direct and Remote
thermometers styles are available.
DIGI-TEL
thermometers are easy to install because sensor assembly
and display indicator can be selected according to the
application and easily connected on-site for installation
into standard thermowells.
The
Display Module
Dual Analog and Digital Display
The circular arrangement of LCD “graduations”
are designed to give the appearance of a traditional
dial instrument, while the exact temperature can be
read from a 4 digit display.
DIGI-TEL
models with a digital only display and with large high-resolution
digits are also available. Modules are all stainless
steel. The heavy-duty industrial assemblies are available
as back, bottom, adjustable angle, or remote configurations.
The unit complies with the vibration requirements of
German Lloyd for marine applications (modules D1A and
D5A excluded). Dust and moisture protection level is
to IP 65 and electromagnetic interference complies with
the requirements of the EC standards.
New Concept, Traditional Design!
The Probe Assembly--Sensor
The temperature sensor is a thin film Platinum RTD,
Pt 1000 2-wire type. Grounding is not necessary due
to minimal resistance change over length. Maximum length
recommended is 163 feet/50 meters. Very low power consumption
of the sensor allows use of solar powered modules, or
up to a 5 year life on battery powered units. Signal
conditioning is performed by the microprocessor. The
small size of the sensor chip allows pinpoint positioning
in the medium for faster response characteristics
Interchangeable
Probe Construction
Probe assemblies for the battery powered models are
interchangeable with all display modules through the
use of a standard watertight connector assembly. Cable
assemblies for Remote Mounted thermometers use the same
interchangeable connectors. The threaded union connection
is a standard 1/2" NPT and 6mm diameter stems fit
into standard bimetal thermowells.
The
Measuring Process
The Tel-Tru solar and battery powered
DIGI-TEL
thermometers rely on a periodic measurement process
with a 3 second cycle time allowing the viewer, even
in passing, to take a real-time reading. An activity
display (a sun symbol at the start of display) indicates
the measurement cycle.
Performance
The microprocessor conditions the signal resistance
of Pt 1000 with a resolution of 12 bits. The numerical
error of measurement is less than 1 Kelvin. This meets
the accuracy requirements for measuring equipment to
EN 13190 class 1, which is within ±1% of the
reading plus 1 degree.
Sensor
Monitoring
The microprocessor continually checks the integrity
of the sensor signal.
Service
Considerations
A significant advantage of the Tel-Tru
DIGI-TEL
thermometers lies in the long-term stability of the electronics
to provide the measurement. Integrated diagnostic routines
continually check the validity of the sensor output. An
error message will occur when there is a short circuit
of the sensor connection, the measured value is out of
range, and when the probe is not connected to the module
or in the event of a sensor failure.