MMT143 moisture and temperature transmitter for oil

Compact. Rugged. Intelligent.
Ideal for OEM applications.

MMT143 moisture and temperature transmitter for oil

Reliable, durable, compact.

  • Continuous measurement of oil moisture

  • For transformer, lubrication and hydraulic oils

  • Excellent pressure and temperature tolerance 

  • Powered by proven Vaisala HUMICAP® technology

  • Traceable calibration (certificate included)

  • Compatible with Vaisala Indigo80 handheld indicator and Insight PC software
     

Compact and intelligent

Compact form-factor  installs quickly and easily in tight spaces. 

Delivered fully assembled and reconfigurable to suit your needs with Vaisala Insight PC software and the Indigo80 handheld.

Water activity

MMT143 measures moisture in oil in terms of the water activity (aw), relative saturation (%RS), and temperature (T). 

Water activity indicates directly whether there is a risk of free water formation. 

The measurement is independent of oil type, age, and temperature.

Water content as ppm

Output in ppm conversion is readily available out-of-the-box, for most common transformer oils, including mineral. 

For other transformer oils, the oil-specific conversion coefficients can be programmed into the transmitter if water solubility is known.

MMT143 moisture and temperature transmitter for oil

Key specifications

  • No consumables
  • Only minimal maintenance needed
  • Calculates moisture content in ppm for transformer oils
     
  • IP66-rated stainless steel construction
  • RS-485 digital output with Modbus support
  • 5–28V (digital) and 18–28V (analog) DC power

    Deliveries to begin Q3/2026.

 

Performance
Water activityTemperature

Range*

  • 0–100 %RS 
    (0–1 aw)

Range:

  • -40 … +80 °C 
    (-40 … +176 °F)

Accuracy:

  • 0–90 %RS (0–0.9 aw) 
    at ±2 %RS (-±0.02 aw)
  • 90–100 %RS (0.9–1 aw) 
    at ±3 %RS (±0.03 aw)

Accuracy:

  • ±0.2 °C (±0.36 °F) 
    at +20 °C (+68 °F)
* Calculates moisture content in ppm for transformer oils 

Resources

Want to know more? Interested in purchasing? 
Ready to evaluate the MMT143? 
Talk to us, Vaisala's specialists are always ready to help your current, 
or next, project achieve operational status and deliver reliable 
measurement data for decision making. 

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