Transformer Oil Gas Analysis with the Bruker TOGA Analyzer equipped with the Bruker Headspace Sampler

Insulating fluids, generally mineral oils, are used in 
transformers. Under normal, mild conditions there is  
very little decomposition.

Occasionally however (localized or general) overheating  
of the oil occurs and decomposition products are formed.  
If the concentration of these gases reaches a critical point,  
the chances of catastrophic transformer failure are high.

The ASTM D 3612 method1 describes in detail three 
different routes.

A. Vacuum Extraction. 
The gases are extracted from the oil via a vacuum  
extraction device and analyzed via gas chromatography.

B. Stripper Column Extraction. 
Dissolved gases are extracted from a sample of oil by 
sparging the oil with the carrier gas on a stripper column 
containing a high surface area bead. The gases are then 
flushed from the stripper column into a gas chromatograph 
for analysis.

C. Headspace Sampling. 
An oil sample is brought into contact with a gas phase 
(headspace) in a closed vessel purged with Argon.  

Application Notes #283028

Transformer Oil Gas Analysis with the Bruker TOGA 

Analyzer equipped with the Bruker Headspace Sampler.

Gases in Transformer 

Oil Analysis

As a result, a portion of a gas dissolved in the oil is  
transferred to the Headspace. 

This application note describes Method C.

Instrumentation 

Gas Chromatograph  
• Bruker TOGA Analyzer based on 450-GC

Headspace Sampler 
• SHS-40 Headspace Analyzer

GC control and data handling 
• Compass CDS software

Figure 1. TOGA analysis, TCD channel.

Materials and Reagents

“True North” DGA Oil Standard by Morgan Schaffer: 
Hydrogen 

88 ppm 

Oxygen  

11163 ppm 

Nitrogen 

40368 ppm 

Methane 

96 ppm 

Carbon monoxide 

89 ppm 

Carbon dioxide   

123 ppm 

Ethylene 

90 ppm 

Ethane   

92 ppm 

Acetylene 

84 ppm

Table 2. TCD, FID, Methanizer settings.

Table 1. Column oven settings.

Safety Class 1
Rate (°C/min)

Step (°C)

Time (min.)

Initial

50

5.0

10.0

75

0.0

20.0

220

10.25

Total Time

25.0

Table 3. Valves.

Time 

(min)

(1) Gas 

Sampling  

Valve

(2) Series 

bypass

Sample

Event  

A

Initial

Fill

Series

OFF

OFF

3.0

Fill

Series

OFF

ON

4.2

Fill

Bypass

OFF

ON

TCD

Ar reference flow

10 mL/min

Temperature

200°C

Filament temperature

254°C

Carrier gas

N

2 /Ar

Total Time

25.0

FID

Temperature

300°C

Ar makeup flow

20mL/min

H

2 flow

10mL/min

Air flow

300mL/min

Methanizer

Temperature

400°C

Figure 3. Schematic overview hardware.

Figure 2. TOGA analysis FID channel.

Sample Preparation

The Morgan Schaffer Calibration Standard is carefully 
transferred into the headspace vial.

The gases are extracted from the oil by means of a 
headspace sampler and injected onto a short Hayesep 
P precolumn and then to a micro packed Carboxen-1000 
column. The fraction containing Hydrogen, Oxygen, 
Nitrogen, Carbon Monoxide, and Methane will elute direct 
from the Carboxen-1000 column to the micro packed 
Molsieve column. Hydrogen, Oxygen and Nitrogen are 
detected by the TCD. Carbon Monoxide, and Methane are 
detected by the FID, after passing the Methanizer. When 
the Molsieve column is bypassed, Carbon Dioxide and the 
C

2 -C3 isomers are eluting from the Carboxen-1000 column 

and detected by the FID after passing the Methanizer.  
The back flush time is set to completely elute the C

3 

isomers. C

4 and higher are back flushed.

Extraction, Method Parameters:

Conditions

www.bruker.com

Bruker Daltonik GmbH

Bremen · Germany
Phone +49 (0)421-2205-0 
Fax +49 (0)421-2205-103 
[email protected]

Bruker Daltonics Inc.

Billerica, MA · USA 

Fremont, CA · USA

Phone +1 (978) 663-3660  Phone +1 (510) 683-4300 
Fax +1 (978) 667-5993 

Fax +1 (510) 490-6586 

[email protected] 

[email protected]

Results and Discussion

Chromatograms of both TCD and FID channels are shown  
in Figure 1 and Figure 2. The complete hardware 
configuration (SHS-40/TOGA) is shown schematically in 
Figure 3.

Repeatability is tested by analyzing multiple samples from 
the same source. Data can be found in Table 4.

Table 4. Repeatability data.

Run

N

2 

Peak Area

CH

4 

Peak Area

CO

2 

Peak Area

1

692201

609

369764

2

696712

606

365757

3

669175

584

361535

4

678626

592

361783

5

709715

577

364403

6

702775

576

376105

7

724545

607

393602

n

7

7

7

Average

696249.9

593.0

370421.3

St.Dev.

18640

14.4

11414

RSD (%)

2.68

2.43

3.08

A graphic representation of the data is shown in Figure 4 
and Figure 5.

Figure 4. Repeatability results of a Transformer Oil.

Figure 5. Repeatability results of a Transformer oil.

Besides the analytical result also the window specified in 
the ASTM D 3612 method is presented.

From the data presented in Table 4, Figure 4 and Figure 5 it 
is clear that the repeatability of the system is well within the 
window specified by the ASTM D 3612.

Conclusion

Full separation of all components of interest, easy and 
reliable quantification results with very good repeatability 
was achieved. 

The analysis of dissolved gases in transformer oil according 
to ASTM D 3612, Method C, can be performed perfectly 
with the Bruker Transformer Oil Gas Analyzer (TOGA 
Analyzer) in conjunction with the Bruker SHS-40  
Automated Headspace Sampler.

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References

1. ASTM Standard D 3612 - 02, “Analysis of Gases Dissolved in  
Electrical Insulation Oil by Gas Chromatography. Method C”,  
ASTM International, West Conshohocken, PA, www.astm.org