LubCos H2O+ II

FAQ

• Can the sensor measure absolute humidity?

  Yes, with prior laboratory measurement of the measured oil and subsequent calibration it is possible. However, this will only apply to the previously measured oil.

• What is relative humidity?

  In contrast to the humidity analysis in the laboratory, in which the water content is absolutely shown in ppm (parts per million), the saturation of the oil can be measured by measurement of the relative humidity. The advantage of the relative humidity with respect to the absolute water content is, that is not necessary to know which oil has been used, in order to judge on the basis of the saturation limit whether free water is present or released.

• With what kind of oils are the sensors compatible?

  Mineral oils, synthetic esters and organic oils

• What are the ommunication options of the sensor?

  The sensor LubCos H2O has a serial interface via which it can be read out and configured. The H2O + II, the level sensors and Vis + are additionally able to communicate via CAN Open.

• Are there remote possibilities?

  There are two possibilities: 1. LubMonVisu with integrated Ethernet Module 2. LubMonConnect in conjunction with CAN / analog converter

• Measuring principle

  The sensor detects the following physical oil characteristics and their changes over time: temperature, relative oil humidity or water activity, relative dielectric constant (relative permittivity) and conductivity of the fluid. In particular, since the conductivity and relative permittivity are very dependent from the temperature, the sensor also defines the values at a reference temperature (40 °C) in addition to the characteristic values at the current temperature . The sensor automatically evaluates state changes. Alarm, warnings and errors are transfered coded via the CAN interface or output via RS232.

• Max. cable length when connecting to RS232 or analogously

  With RS232 not longer than 5 m; with analogous connection the total resistance incl. load resistance must not be more than 200 Ohm.

• Two measurements in the same oil show different rel. humidity

  The relative humidity depends on the temperature. Thus, the oil samples should have the same temperature so as to have the same relative humidity with the same absolute water content. Water in oil is volatile: depending on how the oil sample was sealed, the oil in an initially wet sample may be dry and with a very dry sample, additional humidity could be drawn from the air. "

• Which LubCos sensors are CANopen capable?

  H2O + II, Vis + and Level

• With which measurement principle are the dielectric constant / permittivity determined?

  The measuring principle is based on a combined real and partly imaginary measurement. From the measured capacity the dielectric constant of the fluid can be determined - taking into account the characteristics of the capacitive element.

• Is there a relationship between breakdown voltage and rel. humidity in the oil?

  This is most likely. A higher humidity will probably reduce the breakdown voltage, it will be particularly critical to reach the saturation limit.

• In which range are the values of the electrical conductivity in pS / m for hydraulic fluids?

  This greatly depends on the additives, from a few pS /m to a many thousands.

• Is it possible to make a statement about the breakdown voltage on the basis of the electrical conductivity?

  Yes, it is quite conceivable, if the boundary conditions are right (i.e., are always comparable: humidity, pollution, aging, etc.)

• With which measurement principle is the conductivity measured?

  The sensitive element is a metallic finger structure with two electrodes to which a DC voltage is applied. Depending on the conductivity of the fluid surrounding the sensor element, there flows a defined current. This current is measured by a controller and converted in the conductivity of the fluid.