Brochure · EN — Siemens Energy Grid Technologies Service brochure (2023) for the SITRAM H2Guard Lite, an online single-gas DGA (dissolved gas analysis) system that continuously measures hydrogen — the key gas indicator of any abnormal condition in a transformer — in the insulating liquid of liquid-filled transformers. Covers the fleet-wide monitoring rationale versus offline laboratory DGA, the solid-state thin-film alloy sensing principle (no reference gases, no sensor-element replacement), benefits, scope of work / deliverables, and the full measuring-demands and general-data tables (25–5000 ppm range, 12-48 VDC 10 W, IP68, RS-485 Modbus RTU, 1 year data storage).
Fleet wide transformer monitoring has just become available. Among the reasons for transformer outages, failures related to the winding have the highest ranking. In case of present partial discharge phenomena, which are also referred to as "sparking", the transformer liquid produces internal gases. The key gas indicator of any abnormal condition in a transformer is hydrogen.
One reason for the statistical outcomes in researched failure rates could be that the transformer liquid is usually tested offline by classical DGA analysis in laboratories. This manual procedure is not always trivial and only offers a snapshot-in-time analysis due to the non-continuous test approach.
With the SITRAM H2Guard Lite, the new online DGA system (DGA: dissolved gas analysis), Siemens Energy offers a versatile single gas monitoring system for hydrogen measuring.
SITRAM H2Guard Lite enables asset managers to check the hydrogen health condition of the transformer's insulating liquid continuously. This provides the advantage of trending hydrogen creation / evolution based on historical and present operating conditions.
The actual miniature sensing element is located in the sensor tube, which is installed on any suitable valve in either the liquid phase or gas phase (headspace) of a liquid-filled transformer tank or the pipe system.
SITRAM H2Guard Lite can be easily integrated into superior monitoring platforms using a standard protocol communication interface.
Fleet wide hydrogen gas monitoring; fast detection and reliable data output; easy to install and remove; improved scheduling of maintenance work and downtimes, repairs, adequate personnel support.
Very durable and minimum maintenance in comparison with other products; interoperability and simple operation; price attractive ownership with quick amortization considering classical assessment approaches.
Standard electrical and mechanical connection kit, or individual mechanical connection kit on request; turnkey installation and communications services; expert analysis of monitoring data and customer support; on-site training courses for operation and maintenance of the systems; design, installation, and commissioning of all necessary equipment.
The SITRAM H2Guard Lite has an advantageous compact solid-state thin film alloy design which catalyzes the molecular hydrogen into atoms. They are picked up by the alloy mix and bound into the metallic lattice inside the film. During this process of binding the hydrogen, the bulk electrical properties of the alloy change and are used as measurement basis.
The alloy design does not degrade over time and maintains its accuracy over its life expectancy. Therefore, based on this measurement principle, there is no need for consumables like reference gases which are used in gas chromatography.
There is no need for sensor element replacement, unlike in a classical membrane which is normally used (e.g. fuel cell sensor approaches based on the electrochemical principle or the thermal conductivity detection). In case support is needed, the Siemens Energy global service network is always happy to help.
Measurement performance as printed. The brochure's footnote to this table states: for better understanding please refer to the details in the system manual.
| Parameter | Value |
|---|---|
| Range | 25 – 5000 ppm |
| Accuracy | 20 % of reading or 25 ppm, whichever is greater |
| Repeatability | 10 % of reading or 15 ppm, whichever is greater |
| Response time | < 60 min (90 % of step change) |
| Cross-sensitivity | < 2 % to other gases CO, CO2, CH4, C2H2, C2H4, C2H6, C3H8, etc. |
Electrical, environmental, mechanical and communication data as printed in the brochure. Fidelity note: the physical-dimensions row is transcribed as printed, including the source's compact notation (e.g. 'H39.6 mm', 'W1.6 H1.6 inch'). Unlike the companion SITRAM H2Guard Lite fact sheet, this brochure lists no analogue I/O row and gives the communication protocol as Modbus RTU only.
| Characteristic | Specification |
|---|---|
| Supply voltage / Power consumption | 12-48 VDC 10 W |
| Ambient operating conditions | -40°C…+70°C, indoor/outdoor also in harsh EMC areas, 5 % ... 95 % RH (non-condensing) for complete operating temperature |
| Operating conditions | Pressure and vacuum withstanding; oil temperature, pressure: ≤ 105°C / ≤ 10 bar |
| Physical dimensions and weight | Tube > ¾" NPT / 3.5"; System > L:151 W:39.6 H39.6 mm (L:5.9 W1.6 H1.6 inch), 387 grams |
| Ingress and corrosion protection | IP68 (IEC 60529); C5M (a.o. ISO 12944); weather and UV resistant powder coat (AAMA 2604); cast aluminum enclosure (UNS A03280) with a stainless-steel probe tube (316 type) |
| Resistance to shock and vibration | Among others tested on basis of: DIN EN 60068-2-6 – shock and vibration; DIN EN 60068-2-64 – vibration environmental test; DIN EN 60068-2-27 – shock test for transformer environment. Additional performed tests such as extended, aggressive vibration dwell at 50 and 60 Hz. |
| Data rate | Maximum 1 measurement value per second; self-calibration: 2 h every 12 h |
| Communication | Serial RS-485 – Modbus RTU |
| Memory | 1 year data storage capability |
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