Dissolved Gas in Oil Measurement and Analysis

DGA Monitoring for Power Transformers

Dissolved Gas Analysis - DGA

Dissolved Gas Analysis (DGA) in power transformers is a critical component in condition-based maintenance (CBM) and in identifying faults and preventing unplanned transformer outages. The gas levels in transformer oil can indicate the existence of a fault, and the rate of change in these levels can be used to determine its severity. 

The key fault gases in DGA are hydrogen , methane, ethane, ethylene, acetylene, carbon monoxide and carbon dioxide.

Extraction Levels - Optimus

What Makes Vaisala’s DGA Monitor Unique?

The Vaisala Optimus uses a patented Vacuum Gas Extraction technology, which results in a much more complete extraction of the dissolved gasses as compared to traditional Head Space and other separation methods.  This leads to more accurate and reliable results, independent of the oil type, age or the Total Dissolved Gases.


For actual gas measurement, the monitor uses infrared (IR) gas sensing technology, where Vaisala’s own tunable IR filters allow a wider range of IR scanning offering better gas selectivity. The measurement has integrated vacuum IR reference, which is used continuously to eliminate any drift mechanisms like decrease in light source intensity. With all this we are able to achieve the best long term stability and measurement performance with nothing to service or maintain.

Benefits of Vaisala’s DGA Monitoring Technology


High gas extraction rate, novel vacuum IR reference method and patented autocalibration leads to more reliable results and excellent long-term stability.

Long Lifetime

Maintenance free operation through robust design and hermetic metal structure of the oil and gas handling system. 

No moving parts in the optical IR measurement module.

No consumables and no gas cylinders.

Out of the Box Performance

Online DGA monitoring provides real time view of the transformers condition.

Enabling corrective actions taken on time.