Dissolved Gas Analysis (DGA) for Power Transformers

Vaisala's real-time online DGA monitors help mitigate the risks and safeguard the power industry's critical assets.


DGA - Dissolved Gas Analysis explained

Dissolved Gas Analysis (DGA) of power transformers is critical to condition-based maintenance (CBM), identifying faults and preventing unplanned transformer outages. The gas levels in transformer insulation liquids can indicate the existence of a fault, and the gassing trends, ie. the rate of change in gas 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.

Intelligent monitors for DGA

Utilities and industrial clients can now safely increase equipment performance, prolong lifespans, plan for timely maintenance, and prevent unexpected outages. 

Dissolved gases appearing in transformer oil indicate a fault, while the rate of change in gas concentrations is used to determine the severity of the fault.

A multi-gas DGA monitor, like the Optimus DGA monitor, is your best choice for critical transformers, as it provides a comprehensive understanding of the transformer's condition. On the other hand, a single-gas monitor, such as the MHT410, can be used as a simple early warning indicator.

Total gas pressure

Maximize your power transformer's operational life

Total gas pressure is a groundbreaking method for detecting air leaks into your transformer. It's a robust, reliable, and intuitive method to ensure your transformer is still sealed against ambient air and its oxygen.

Oxygen will prematurely age and weaken the paper in your transformer's windings, potentially shortening your transformer's operational life by years. Total gas pressure is the answer. And comes as standard in the Vaisala Optimus™️ OPT100 online DGA monitor.


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.

Maintenance-Free Total Cost Savings with the Optimus™️ DGA Online Monitor

You get maintenance-free monitoring with the Vaisala Optimus™ DGA – no consumables, mechanicals or need for calibration. Compared to traditional DGA monitors, the Optimus offers real-time monitoring with no false alarms, no maintenance – and no extra lifetime costs.

By providing reliable trend data in real time and without false alarms, Vaisala DGA Monitors help you detect upstream problems.

Dissolved Gas Analysis (DGA) product highlights

Vaisala’s Optimus™ DGA Monitor OPT100 for advanced dissolved gas analysis with total gas pressure method, detecting air leaks in transformers.

Optimus™ DGA Monitor OPT100

Ensure your power transformer stays operational longer. OPT100 brings unmatched long-term stability, reliability and measurement performance for detecting the formation of fault gases.
DPT145 Multiparameter Transmitter for SF6 Gas

Multiparameter Transmitter DPT145

Our uniquely capable Multiparameter Transmitter for SF6 gas opens for you the world of online measurement of dew point, pressure, and temperature. It also calculates four other values, including SF6 density.

Turn your DGA data into Duval Triangles and Pentagon

Visualize the state of your power transformer, with Duval Triangles, Pentagon, and gassing trend graphs. Supports IEC & IEEE standards, as well as data import & export.

Try the DGA Calculator

Insights, webinars and more


New DGA Calculator visualizes the state of your transformer

Turn your DGA data into Duval Triangles, Pentagon, and gassing trend graphs. Supports IEC & IEEE standards, data import & export and more.

Try the calculator


Practicalities of measuring moisture in transformers online

Vaisala's Senja Leivo and Riku Rantala go head to head to discuss practicalities and real-life lessons learned, tackle audience questions and offer highly valuable, directly applicable insights into measuring moisture in transformers.

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Moisture in Transformers Q&A eBook

Filled with your actual questions answered by Vaisala's experts, this nearly 40-page eBook is a versatile manual for anyone whose business it is to maintain guard against and understand the effects of moisture in power transformers.

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Online DGA Monitoring of Power Transformers

Find the fundamentals of dissolved gas analysis for power transformers and get to know the data from field tests of Vaisala online monitors.
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Discover four core strategies to improve your power transformers' lifespan

Download this eBook and arm yourself with practical and scientific knowledge. Learn how you can protect your high-voltage assets and improve your operations through online DGA monitoring, and take better-informed decisions, on-time and on budget.

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The science of moisture in transformers

In four episodes, you'll get a deep dive into both the science and practice of moisture in oil and measuring it, culminating in a two Expert Q&A sessions with your insights & questions answered by the experts.

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Video blog

Infrared DGA and aging oils – possible without recalibration?

Infrared technologies, whether PAS or NDIR, are a great option for DGA monitoring. Infrared also makes it possible to create a maintenance-free DGA monitor that does not need any recalibration — if you can solve the challenge of oil aging.

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Customer case

Using online DGA to safeguard a transformer's end-of-life operation

The following case study explores the detection of severe faults and the overall monitoring process and procedure during an old transformer's final months in service - it's end-of-life (EOL). 

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More robust air leak monitoring for power transformers – Total Gas Pressure

Ever-increasing efficiency targets concern all industries and their assets. Power transformers are no different. Maximizing and extending their lifetime is all about meeting this challenge.

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