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Online DGA

Next generation On-Line Multi-Gas DGA

Dissolved Gas Analysis (DGA) and moisture measurement of insulating fluids are recognized as the most important tests for condition assessment of transformers. In previous years, multi-gas DGA was traditionally confined to a laboratory environment, with infrequent off-line manual sampling forming part of time-based maintenance strategies. However, as the global average age of transformers continued to rise, the possibility of rapid ageing, unplanned outages and even catastrophic failure between off-line tests also increased, leading many asset owners to adopt on-line DGA monitoring strategies to increase network reliability.

In the early 2000’s, GE’s Kelman™ range of analysers brought consumable-free on-line multi-gas DGA to the market and GE is now proud to introduce the Kelman DGA 900, our next generation multi-gas on-line DGA and moisture analyser. At its heart lies an evolved implementation of GE’s proven Photo- Acoustic Spectroscopy (PAS) measurement technology, providing laboratory challenging levels of precision and repeatability with no consumables and no need for frequent re-calibration. Benefiting from over 40 years of global DGA vendor experience, the Kelman DGA 900 encapsulates learnings and improvements derived from its predecessors to bring improved performance, innovative new features, enhanced user experience and increased robustness

Key Benefits

• Provides remote alert and multi-gas diagnostic of deteriorating transformer condition
• Expedites operational decisions without needing to go to site for manual oil sampling
• Issues can be detected in their infancy, avoiding unexpected failures and facilitating planned outages
• Anchors condition based maintenance and asset replacement strategies on hard data
• No need for consumables or frequent recalibration to operate at optimum performance
• New “Rapid Mode” provides near real time insight on fast developing faults
• Enhanced computing power, highly scalable I/Os and integrated HMI combine to provide a powerful highly flexible transformer monitoring solution
• Compatible with mineral insulating oils and newer ester based fluids (natural and synthetic)


The Kelman DGA 900 is an invaluable foundational tool for implementing Asset Performance Management (APM) across electrical generation, transmission and industry, enabling a condition based asset replacement strategy and delivering improvements in system reliability and availability. A DS-Agile™ and PREDIX™ Grid APM ready device, the DGA 900’s wide range of communication methods and protocols enables connection to those platforms and integration with GE’s Perception™ transformer fleet management software as well as other software, historian and SCADA systems.


 LDLUDLAccuracy*RepeatabilityAvailable in Rapid Mode
Hydrogen (H₂)5 –5,000 ppm± LDL or ±5%< 3%
Carb. Monox. (CO)1 –50,000 ppm± LDL or ±3%< 2%
Methane (CH₄)2 –50,000 ppm± LDL or ±3%< 2% 
Acetylene (C₂H₂)0.5 –50,000 ppm± LDL or ±3%< 2%
Ethylene (C₂H₄)1 –50,000 ppm± LDL or ±3%< 2% 
Carb. Diox. (CO₂)20 –50,000 ppm± LDL or ±3%< 3%
Ethane (C₂H₆)1 –50,000 ppm± LDL or ±3%< 2% 
Oxygen (O₂)100 –50,000 ppm± LDL or ±5%< 2%
Nitrogen (N₂) **10,000 –100,000 ppm± LDL or ±15%  
Moisture (H₂O)0 –100% RS (in ppm)± 3% RH< 3%

*whichever is greater. Accuracy quoted is the accuracy of the detectors during calibration. Gas-in-oil measurement may be affected by oil type and condition. Repeatability as measured from final production test data.
** N₂ value is calculated and available on free-breathing transformers only.


4x sunlight visible LED arrays
Backlit 7” inch color resistive touch LCD screen (800 x 480)
Integrated embedded secure webserver (https)

Analogue Inputs

Up to 15x optional analogue inputs for load CTs, PT100 inputs or 4–20mA sensors

Digital Output

USB port (type B connector) for local connection to laptop computer for configuring the system
Wi-Fi (802.11b/g/n)
Serial output (RS-485)
1Gb Ethernet (RJ45) standard with fiber-optic options
GSM/GPRS or CDMA/LTE modem options

Digital Protocols

Modbus® as standard
DNP3 or IEC 61850 (Ed 1 or 2) options


Alarm setting screens/scenarios, based on gas level, gas rate of change and moisture level, assignable to relays
6x standard and up to 18x dry contact relays (type C, SPDT), NO/NC, 10A at 250Vac resistive load, 10A at 30Vdc resistive
load Separate Service Alarm with own relay



Operating ambient temperature :- -40°C to +55°C (-40°F to +131°F)

Operating ambient humidity :- 0-95% RH, non-condensing

Oil temperature at valve*** :- -20°C to +120°C (-4°F to +248°F)

Oil pressure at valve :- 0-700KPa (0-100psi)


***Based on testing carried out using VOLTESSO™ 35 mineral oil, over a ¼” pipe run of 10 metres or less from oil supply or
return valve to monitor connection point and on transformer oil supply valve volumes of 200ml or less. For oil temperatures
colder than -20ºC, GE recommends the use of heat trace cabling on piping.


IP56 certified
Powder coated aluminium (RAL9002)
Unpainted 316 Stainless Steel option

Power Requirements

AC :-Nominal 100-240 Vac, Range 85-264 Vac, 4A

DC :- Nominal 100-250 Vdc, Range 90-300 Vdc



 Analysis UnitHub Unit
Dimensions600 x 484 x 330 mm600 x 380 x 330 mm
 23.6 x 19.1 x 13.0 in23.6 x 15.0 x 13.0 in
 73.6 lb40.8 lb



Mounting stand
Sun canopy
Umbilical cable between units
Analogue output of gas values

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