Ahlborn ALMEMO 2690-8A, Руководство по эксплуатации

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10. Measuring using Measuring-Menus
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10.2.5
Temperature Compensation
Sensors with measured values that are strongly depending on the temperature
of the measuring medium are, in most cases, equipped with a specific temper-
ature sensor and the instrument will automatically perform a temperature com-
pensation (s. 11.3.9 measuring range list ´w. PC´). However, dynamic pressure
probes and pH probes are also available without a temperature sensor. If the
temperature of the medium deviates from 25°C the following measuring errors
must be considered:
e.g. error per 10 °C: Compensation range: Sensor:
Dyn.press: approx. 1.6% -50 to 700 °C NiCr-Ni
pH probe: approx. 3.3% 0 to 100 °C Ntc or Pt100
Compensation at constant temperature can be activated via the Temp Comp
(Temperature compensation) function e.g. in the
Meas.Correction
(Measured
value correction) menu.
Entering the compensation temperature in the function
:
Temp Comp: 31.2°C
Continuous temperature compensation with external temperature sensors can
be activated either via the reference channel of the sensor to be compensated
or by configuring any one temperature sensor as reference sensor with “*T” in
its designation; (see 11.3.2).
10.2.6
Atmospheric Pressure Compensation
Some measuring variables depend on the environmental atmospheric pressure
(s. 11.3.9 measuring range list ´w. PC´). As a result, higher deviations from the
normal pressure of 1013mbar can cause corresponding measuring errors:
e.g. error per 100 mbar: Compensation range:
Rel. humidity psychrometer approx. 2% 500 to 1500 mbar
Mixture ratio, cap. approx. 10% vapour pressure VP to 8 bar
Dynamic pressure approx. 5% 800 to 1250 mbar (error < 2%)
O
2
saturation approx. 10% 500 to 1500 mbar
Therefore, the atmospheric pressure should be considered (approx. -
11mb/100m over mean sea level, MSL) especially during use in a corresponding
height above sea level.
This device now incorporates - for the first time - a dedicated atmospheric pres-
sure sensor, which is used automatically in all possible compensation functions.
This atmospheric pressure value is also made available in a function channel.
(see 11.3.10) Alternatively, atmospheric pressure can be measured using an
external sensor. If the designation is programmed to ´
*P
´, the measured value
concerned will be used for atmospheric pressure compensation for the following
channels. (see 11.3.2, Manual 6.7.2) However, the
atm. pressure
can still be
programmed in the
device configuration
or in a user-defined measuring menu
as well. (see 11.5.6)
To resume internal measuring operations this value must be deleted.