LumaSense SmartDGA, Hardware Manual

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SmartDGA Hardware Manual System Overview
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10. Once the gas has equilibrated, its absorption levels are collected for about 10 minutes for
data processing.
11. Ambient air is passed across the Hydrogen and Oxygen sensors, conditioning them for
reading gas levels.
12. The Zero level for the Hydrogen and Oxygen is read for about 1 minute.
13. Ambient air is used to push the gas collection volume past the Hydrogen and Oxygen
sensors. The sensors read their gases for 1 minute.
14. As ambient air continues to be pushed through the instrument, the NDIR absorption levels
for ambient air is collected for about 10 minutes.
15. The data is processed.
16. The cycle is completed and the oil valves are closed.
17. The EZHub unit reads the results from the SmartDGA instrument.
18. The pressure equalization routine starts.
2.2.4 Oil-Gas Separating Membrane
Gases dissolved in the Transformer/LTC insulating oil are
sampled by the SmartDGA instrument via an amorphous
polymer membrane. The non-porous membrane absorbs
gases dissolved in the oil and transfers them to a closed gas
sample space while preventing large oil molecules from
passing. A porous metal frit support prevents distortion of
the membrane into the gas sample space allowing it to
withstand high oil pressures.
To protect the membrane against the application of
negative pressure, the oil pressure is continuously monitored and the oil valves can isolate the
membrane from the oil tank. There is a metal plate with a grid of holes on the side of the
membrane to add further support.
At the beginning of each SmartDGA measurement cycle, a flow-controlled pump refreshes an
internal reservoir with oil from the transformer/LTC system. During gas collection, the same pump is
used to continuously replenish oil at the surface of the oil-gas separation membrane to expedite gas
transfer. Measurements of gas in the sample space as well as oil temperatures and pressures are
used to conduct the dissolved gas analysis of the oil.