Delta OHM HD2107.1, Operating Manual

Page: 14 / 38

HD2107
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V2.3
THE PROBES
The instrument works with temperature probes fitted with the SICRAM module (with a Platinum
Pt100 sensor with 100
Ω resistance) and with direct 4 wire Pt100, direct 3 wire Pt100, 2 wire Pt1000
and Ni1000 sensors. The excitation current was chosen in order to minimize the sensor self-heating
effects. The SICRAM module acts as an interface between the sensor on the probe and the instru-
ment: there is a microprocessor circuit with a permanent memory inside the module that enables the
instrument to recognize the type of probe connected and to read its functioning information.
The probes with SICRAM module are automatically detected by the instrument, while the direct
probes must be set up in the
Probe type menu item (please see the description of the menu on page
10).
The probe is detected during turn on, and this cannot be performed when the instrument is
already on, therefore if a probe is connected and the instrument is on, it is necessary to turn it
off and on
.
T
EMPERATURE MEASUREMENT
In all versions the temperature sensor is housed at the end of the probe.
The response time for the measurement of the temperature in
air is greatly reduced if the air is mov-
ing. If the air is still, stir the probe. The response times are longer than those for liquid measure-
ments.
The temperature measurement by
immersion is carried out by inserting the probe in the liquid for at
least 60mm; the sensor is housed in the end part of the probe.
In the temperature measurement by
penetration the probe tip must be inserted to a depth of at least
60mm, the sensor is housed in the end part of the probe. When measuring the temperature on frozen
blocks it is convenient to use a mechanical tool to bore a cavity in which to insert the tip probe.
In order to perform a correct
contact measurement, the measurement surface must be even and
smooth, and the probe must be perpendicular to the measurement plane. A contact measurement is
hard to perform due to various factors: the operator must be experienced in handling the probe and
consider all the factors influencing it.
So as to obtain the correct measurement, the insertion of a drop of oil or heat-conductive
paste is useful (do not use water or solvents). This method also improves the response time.
The °C, °F or °K unit of measurement can be chosen for display, printing, and logging using the
UNIT/UserCal key.
Calibration of the temperature probe on line with the instrument
To calibrate the probes correctly, a knowledge of and abiding by the physical phenomena on which
the measurement is based is fundamental: this is the reason why it is recommended to abide by what
is reported below carefully, and only to perform new calibrations if technically proficient and using
the suitable equipment.
The probes fitted with SICRAM module are calibrated in the factory and the calibration pa-
rameters are recorded in the module.
All probes with direct input are checked for conformity
with class A tolerance according to norm IEC751 - BS1904 - DIN43760.