MOP301 Insertion Moisture in Oil Probe with Modbus RTU
  The MOP301 insertion probe measures accurately water activity (aw) and temperature (T) in lubrication, hydraulic and insulation oil. In addition it calculates the absolute water content of the oil (x) in ppm. The slide fitting allows for easy installation and removal under pressure up to 20 bar.
Precise and reliable measurement of oil moisture The E+E humidity sensor elements used in the MOP301 are characterised by particularly good long-term stability and resistance to contamination. They are the basis for the high accuracy and reliability of the moisture and temperature measurement.
Versatile in Use

Mechanically, the MOP301 impresses with a robust stainless steel housing with protection class IP66, an oil-resistant cable and a moulded M12x1 plug connection. It can be used in a temperature range from -40 to 120 °C and up to 20 bar pressure.


Different probe and cable lengths as well as the slim design allow a particularly flexible installation of the MOP301. Thanks to the practical process connection with ISO or NPT thread, the immersion depth can be set precisely. With the aid of an optional ball valve, the sensor can be installed and removed without interrupting the process. 

Measured values and interfaces

The MOP301 provides the moisture content of the oil as an absolute or relative value. The water activity (aw) provides information about how close the oil is to the saturation point at a certain temperature. The water content (x) indicates in absolute terms the moisture level is expressed as water content (x) in ppm, representing mg water / kg oil. Based on the measured water activity (aw) and temperature, the MOP301 calculates the absolute water content (x) in ppm.

The oil-specific parameters required for the calculation can already be preconfigured when ordering or can be stored with the help of the PCS10 Product Configuration Software.

Typical applications  
Monitoring of transformer oil
  lubrication oil
  hydraulic oil
  diesel fuel
Key Features MOP301 High measurement accuracy and wide temperture range
  Suitable for transformer, lubrication and hydraulic oil
  Process connection with ISO or NPT slide fitting
  Pressure tight up to 20 bar with the optional ball walve
  Calculation of water content x [ppm]
  Stainless steel enclosure and filter cap with IP66 rating
  RS485 with Modbus RTU
  Editable Modbus-Map Area
  Moulded M12x1 connector
  Oil resistant cable
Technical data MOP301  
-40…120 °C (-40…248 °F)
ACCURACY ±0.02 aw
±0.15 °C