8.2.Measuring principle
The conductivity in electrolytes is obtained via an electro-chemical resistance measure-
ment using a 4-electrode measuring cell. An AC voltage with a frequency of approx. 1
kHz is applied to the electrodes. The current flowing through the test object is conver-
ted into a voltage. This voltage is rectified via a true RMS (TRMS) converter, smoo-
thed, and then fed to an 18-bit A/D converter. The temperature is measured by means
of an NTC sensor.
Measuring quantities and ranges
Two measuring channels (depending on type) are available (factory default settings).
Designation
Quantity
Measuring range
Units Resolution
1. Temperature
D t
See technical data for probe
°C
0.01 K
2. Conductivity 50 mS
DLF2
See technical data for probe
mS
0.001 mS
The sensor is already adjusted on delivery and ready for use. Temperature compensati-
on is preset to a linear characteristic with a temperature coefficient of 1.90 %/K. In
the measuring operation the sensor must be lowered at least 30 mm into the liquid so
that the electrodes are completely immersed.
8.3.Configuration via the sensor menu
The sensor parameters (measuring quantity and range, temperature compensation, probe
adjustment) can be configured in the sensor menu either on a V7 measuring instrument
or on the PC using the ALMEMO
®
Control software (V. 5.14.0.330 and above).
Note: The ´ZERO´ and ´ADJ´ keys are only enabled if the
locking of the sensor (locking level 0) has been disabled.
8.3.1.Configurable measuring quantities and ranges
In the D7 sensor it is possible to configure not only the temperature range on the first
measuring channel but also any one of three conductivity ranges from the following list
on the second measuring channel. (* factory default settings)
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