Total Dissolved Gas Content ( TDGC ) for Insulation Liquids accord. To IEC 567 and IEEE C57.104-1991

Automatic analysis of the dissolved gases in oil-filled transformers
The analysis is done in 2 steps which guarantee a very high selectivity and sensitivity
in the determination of dissolved gases:
1. Gas separation by means of fully vacuum degassing ( accord. to DIN EN 60567,
DIN IEC 599 and IEEE C57.104-1991) and display of results
2. Option: Following the determination of the total gas content a gas
chromatographic analysis can be made.

Both steps are synchronized via a micro-processor control thus a fast and reliable
measurement procedure is guaranteed.

Vacuum Degassing
A newly invented vacuum degassing method (Patent pend. DE 102 52 652 4)
de-gasses the oil sample periodically. After extraction through a 4 step vacuum
pump the gases are dosed into vacuum chamber and separated. The gases are
evacuated from the vacuum chamber with a vacuum pump; therefore a very high
accuracy can be achieved.

In and outlet of the oil sample as well as the switching valve are micro-processor
controlled, a feedback of the oil into the transformer is possible. A linear pressure
sensor measures the total gas content online which is a very important quality
parameter for the characterization of the transformer load.

The injection of the gas sample into the gas chromatograph is via a fixed mount
and heated transfer pipe. An additional port for withdrawal of gas samples is
installed.

Control and Evaluation
The system is controlled by a micro-processor; a serial interface (RS 232) allows
for transferring the data to a remote computer.
The intervals of the analysis cycle can be freely defined by the operator (number of
analysis/day or hour).
The system has 8 additional analog inputs (0 -1 V) for the measurement of other
transformer parameters (Oil temperature, winding temperature, ambient conditions
etc.) The connection of these external sensors is through relay contacts (N/C or N/O,
to be specified by the customer).

Display of results
All results of the total gas content are displayed in Vol% and are stored in a
databank.
The results are displayed on the monitor, in a spreadsheet and in a printed report. All
these data can also be transferred and displayed on a remote computer. All data
is continuously stored in a measurement file.
The results are stored together with all measurement parameters in a log.file. The
history of the stored data starts with the day of commissioning and covers several
years.