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Power Transformers

​​​​​​Online Monitoring of Hydrogen and Moisture in ​Oil of Power Transformers

Power transformers are critical components in any electricity grid. Age, increased load levels, and network failures all take their toll on transformers, leading to an increased risk of unpredictable faults and outages.

Online and real-time condition monitoring of power transformers can keep them operating safely and with maximum efficiency, while supporting the planning of timely maintenance actions that can extend operational lifetime and prevent unexpected and costly outages.

Moisture reduces the insulating properties of transformer oil, resulting in more rapid aging of the transformer. Traditionally, oil moisture readings have been taken at periodic intervals. However, because moisture levels can change rapidly, periodic sampling is not sufficient.

Dissolved gas levels in transformer oil indicate the existence of a fault and the rate of change in these levels is used to determine its severity.

Power Transformer Monitoring From Vaisala

The Vaisala Optimus™ OPT100 DGA Monitor for Transformers is a comprehensive multi-gas DGA for your critical power transformers. The monitor delivers out-of-the-box performance, completely eliminates false alarms, and gives you the best long-term stable measurements of any device on the market – with no need for maintenance. 

The Vaisala Moisture, Hydrogen, and Temperature Transmitter MHT410 provides reliable monitoring of insulating oil in power transformers. Unlike conventional solutions, the MHT410 sensors take measurements directly from representative oil in order to provide reliable trend data. Using non-membrane hydrogen technology, the MHT410 can handle under pressure and overpressure conditions, and never depletes. The transmitter can be installed in minutes by  one person, and its robust design – with no pumps, hoses, or valves – ensures long-term stability.    

The Vaisala HUMICAP® Moisture and Temperature Transmitter Series for Oil MMT330 accurately measures the moisture in transformer oil, giving an online, real-time assessment of the oil's condition, an indicator of how well the transformer is operating. The transmitter monitors moisture levels at all ambient and operating conditions and is compatible with any insulating oil. The measurement can be connected to the substation data-collection system directly. 

The Vaisala HUMICAP® Hand-held Moisture Meter for Oil MM70 is a lightweight portable unit recommended for occasional spot-checks. 

The Vaisala DRYCAP® Dewpoint and Temperature Transmitter Series DMT340 is used for measuring dew point during insulation drying. When building a new transformer or overhauling an existing unit, the cellulose insulation is dried by applying heat and a vacuum. After drying, the tank is purged with dry nitrogen. Measuring the dew point is a widely used method for monitoring the drying process and confirming the final dryness after the nitrogen purge.

The Vaisala DRYCAP ®Hand-Held Dewpoint Meter DM70 is a lightweight handheld device that enables quick and reliable verification that acceptable moisture levels have been achieved.​

Transformer oil testing: online monitoring of transformer oil with moisture and temperature transmitters from Vaisala

Transformer Oil Moisture Monitoring 


New product: MHT410 Moisture, Hydrogen, and Temperature Transmitter for Online Transformer Condition Monitoring 

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