Spot and stop water contamination

Spot and stop water contamination
Senja Paasimaa
Application Manager
Helsinki, Finland
Spot and stop water
New intelligence for continuous on-line
measurement of moisture in oil
Several power generation and transmission networks have various oil filled
systems, for example, transformers
and turbines, where oil acts as an insulating material, lubricant and/or cooling
agent. As water contamination reduces
the performance of oil, moisture is an
important factor determining the condition of different types of oils. With online information on the quality of the oil,
preventive actions can be taken and the
maintenance costs cut substantially.
Lubrication systems
Water contamination reduces the performance of lubrication oil. Excess moisture, particularly free water, increases the
risk of corrosion, overheating, machine
malfunction and other problems. Therefore measuring and controlling the moisture in lubrication systems is essential
to avoid costly failures and to ensure
reliable performance of the equipment
at all times. Monitoring the moisture in
oil within lubrication systems helps to
plan servicing and prevent unscheduled
The detection of moisture in oil is also
an essential part of a comprehensive
transformer maintenance program. Oil
immersed transformers rely on oil for
cooling, protection from corrosion and
as an important component of their insulation. Excessive moisture in oil causes
accelerated ageing of the insulation materials and reduces their dielectric strength.
In extreme cases this can result in arcing
and short circuits within the windings.
If accurate moisture measurements are
available, leaks in the oil system can be
detected in time as water is absorbed
from the surrounding air.
New Vaisala solutions
The new Vaisala HUMICAP Moisture
and Temperature Transmitter Series for
Oil MMT330 enables fast and reliable
28 | Vaisala News 172 / 2006
The new Vaisala HUMICAP Moisture
and Temperature Transmitter Series
for Oil MMT330 enables fast and reliable detection of moisture in oil.
detection of moisture in oil. The MMT330
can be used in on-line moisture monitoring and as a control device, allowing
separators and oil driers to be started
only when needed. Proper monitoring
saves both oil and the environment. With
the MMT330, it is easy and economical
to monitor moisture in oil.
Reliable Vaisala
HUMICAP® technology
The MMT330 incorporates the latest
generation of the Vaisala HUMICAP
sensor, resulting from ten years of field
experience. The sensor was developed
for demanding moisture measurement
in liquid hydrocarbons. Its excellent
chemical tolerance provides accurate
and reliable measurement over a wide
measurement range. The operation is
based on the measurement of changes
in capacitance as the film absorbs water
molecules from oil.
Indicates the margin
to water saturation
The MMT330 measures moisture in oil in
terms of water activity (aw) and temperature (T). The measurement indicates the
margin to water saturation in oil and is
therefore independent of oil type, age and
Water content as
ppm conversion
In addition to water activity, the MMT330
can output ppm, the average mass
concentration of water in oil. Vaisala
has this conversion readily available for
mineral transformer oil. For other oils,
the oil specific conversion coefficients
can be programmed to the transmitter
by the user, if the water solubility of the
oil is known.
Graphical measurement
trend and historical display
The MMT330 can be ordered with a large
numerical and graphical display with a
multilingual menu. It allows the user to
monitor measurement trends over a oneyear period.
Versatile outputs
The MMT330 provides up to three analog
outputs. Galvanic isolation of supply
power and analog outputs are also available. The RS232 and RS485 can be used
for serial interface. In addition, an alarm
relay option is available.
Easy installation
The Vaisala HUMICAP Moisture and
Temperature Transmitter Series for
Oil MMT330 has three different probe
options available, enabling various application installations with wide pressure
and temperature ranges of up to 250 bar
and 180 °C. In addition, the MMT330 has
several options for transmitter mounting.
Transmitters are delivered pre-configured
with all settings installation ready.
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