CMC OilQSens OQ 3000, Руководство пользователя

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cmc Instruments GmbH 11
version 3.6-05/18
4. DESCRIPTION
OilQSens

is an instrument for measuring conductivity, relative permittivity and
temperature of oils and other fluids.
The OilQSens

consists out of two basic modules, sensor and communication unit with
communication module.
PLEASE READ THE ENTIRE MANUAL BEFORE OPERATING THE ANALYZER!
OilQSens

is fully microprocessor controlled and is designed to operate in rough field
service. The amplifier is a high technology, solid state unit.
The measuring signals of the sensor are transferred via special high quality water proof
connectors (IP68) to the communication unit.
4.1 PRINCIPLE OF OPERATION
The OilQSens

sensor measures the electrical conductivity, relative permittivity and
the temperature of the fluid.
The sensor consists of three plates which are arranged parallel to each other. These
form a capacitor. The fluid flows between the capacitor plates and forms the dielectric
between the plates.
Thus, it is possible that the capacity of this capacitor can be measured. On the basis
of capacity, the relative permittivity is defined. The dielectric properties of the oils are
especially determined by the water content, which, in the case of products that are not
enriched with additives, becomes accessible via the accurate measurement of the
relative permittivity. Pure water has a relative permittivity of 80, oil has a relative
permittivity of 2 to 5. In the case of oils enriched with additives, statements on the
degradation of additives can also be derived from changes in the relative permittivity.
Furthermore, the resistance between the plates can be measured. For instance, metal
abrasion, broken oil molecules, acids or oil soap all bring about an increase in electric
conductivity, which, on account of the low conductivity value of oil as compared to all
these contamination products, directly correlates to the degree of pollution. Since oil is
an excellent insulator, it has conductivities between 1.0 to 90000pS/m. Opposite is the
conductivity of pure water which is
a few μS/m and metals which are some MS/m. This
means with water is more conductive than oil by a factor of 300 to 10
5
or metals than
oil by a factor of 10
16
.
The temperature is measured to allow comparison of permittivity and conductivity
values at different temperatures. The electrical parameters of relative permittivity and
conductivity are temperature dependent. A self-learning, adaptive temperature
compensation algorithm allows accurate comparison of data taken at different
temperature.