4 Product description
Messko GmbH 202016 BA4001150/10 ENMSENSE
®
DGA 2/3
4 Product description
The detection of dissolved gases in transformer oil is generally considered to
be the first indication of emerging faults in transformers. Several interna-
tional standards highlight the relevance of this examination method, includ-
ing the IEEE Std C57.104™-2008, IEC 60422, IEC 60567 and IEC 60599
standards.
The Dissolved Gas Analysis (DGA) method is fast, low-cost and possible
without disconnecting the transformer. The composition of the gases pro-
vides initial key information on fault events such as partial discharges, over-
heating, arcs and overload. This knowledge enables sound risk assessment
and the early initiation of measures for corrective action.
The standards listed above recommend that oil samples be taken at regular
intervals and that these be analyzed by a laboratory. In addition to a DGA,
further examinations are usually performed, such as the determination of the
moisture in oil, the dielectric strength and the turbidity.
Two gases in particular are to be considered during a DGA: hydrogen (H2)
and carbon monoxide (CO), since these are generated in virtually all occur-
ring faults. The occurrence of hydrogen is an indication of electrical faults in
the transformer, and carbon monoxide is generated during the decomposi-
tion of the paper insulation, which is caused by overheating.
Increased moisture in the oil significantly reduces the dielectric strength of
the insulating oil and also promotes paper decomposition; thus, monitoring
the water content (H2O) in the oil provides essential additional information
for the assessment of risks.
Continuous online monitoring of these two gases and the moisture enables
early detection of emerging, potentially harmful trends. As soon as defined
warning thresholds are exceeded, further analyses can be carried out and
countermeasures can be taken at an early stage. The costs for quickly im-
plemented measures are generally much lower than those implemented at a
later date, and especially after a failure of the transformer with the resulting
consequential costs.
Messko has developed the MSENSE® DGA 2/3 online DGA device for pre-
cisely this purpose. It continuously monitors the gas concentrations of hydro-
gen and carbon monoxide (MSENSE® DGA 3) as well as the moisture in oil,
and issues warning or alarm messages if defined gas or moisture concentra-
tions are exceeded or if the rates of increase are too high.
This chapter contains an overview of the design and function of the product.
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