Presentation · EN — Seventeen-slide Siemens Energy Grid Technologies Service sales presentation (2023, classified Unrestricted) for the SITRAM H2Guard Lite online hydrogen sensor for liquid-filled transformers. Part 1 makes the transformer-monitoring case: windings dominate the failure distribution (40 %), dissolved gas analysis is the first monitoring priority, and hydrogen is the key gas generated in most failure modes — so fleet-wide hydrogen monitoring plus multi-gas DGA on critical units is presented as a valid condition-based-maintenance strategy. Part 2 details the product: a maintenance-free solid-state palladium-alloy sensor that measures hydrogen directly in the insulating liquid or the headspace (no membrane, no gas extraction, no manual calibration), installable on any oil-filled or nitrogen-blanketed transformer, with a rugged ¾"-14 NPT / 4-pin M12 package (12-48 VDC, 10 W; RS485 Modbus RTU) measuring 25–5000 ppm hydrogen at -20° to 105° operating temperature. The deck positions it as the early-warning entry point of the SITRAM/Sensformer monitoring portfolio, below the multi-gas SITRAM Multisense 5 and 9 DGA sensors.
All components of a transformer may cause failures and outages. The distribution of transformer failures shown in the deck: windings 40 %, tap changer 27 %, bushing 17 %, lead exit 7 %, others 6 %, core 3 % (source cited on the slide: S. Tenbohlen, "Diagnostik elektrischer Betriebsmittel 2014", 6. ETG-Fachtagung, Berlin, Germany).
Consequences of transformer failures listed: injury to personnel; production loss; supply bottlenecks; impairment of results and of reputation; regulations and/or contractual penalties due to interruption of energy supply; environmental risks (emissions etc.). As an illustrative financial impact, the deck quotes € 330,000 daily forgone profit following the outage of a 760 MVA GSU transformer (same published source).
With monitoring, the condition of many components can be assessed and operational risks minimized. The deck's prioritization of monitoring efforts, mapped against the failure distribution: (1) dissolved gas analysis (DGA), (2) tap changer monitoring, (3) bushing monitoring.
The deck positions the SITRAM H2Guard Lite within a monitoring portfolio ordered by diagnostic level: SITRAM H2Guard Lite (hydrogen sensor) delivers early warning; SITRAM Multisense 5 & 9 (DGA sensors) deliver early failure detection and DGA trending; Bushing Monitoring (bushing monitoring sensor) delivers early fault detection in the bushing; and Sensformer (online monitoring) delivers comprehensive diagnosis — 'a comprehensive monitoring portfolio for any customer requirements: from simple early warning to fleet analytics'.
The deck's gas-generation matrix maps transformer failure modes to the key gases they produce, and brackets the coverage of each sensor: SITRAM H2Guard Lite measures H2 only; SITRAM Multisense 5 covers H2, CO, C2H2, C2H4 and CH4; SITRAM Multisense 9 covers all eight listed gases. The takeaway arrows read: 'Sense hydrogen to get aware of a failure' and 'Sense multiple key gases to distinguish between failure scenarios'.
Gas generation by failure mode as printed (footnote: * indirectly as side effect):
| Transformer failure | Key gases generated |
|---|---|
| Decomposition of cellulose | H2*, CO, CO2 |
| Decomposition of oil | H2, C2H2, C2H4, CH4, C2H6 |
| Leaks in oil (i.e. expansion vessels) | CO, O2, CO2 |
| Thermal faults (cellulose) | H2, CO, CH4, O2, CO2 |
| Thermal faults in the oil @150°C - 300°C (T1) | H2, C2H4 (trace), CH4, C2H6 |
| Thermal faults in oil @300°C - 700°C (T2) | H2, C2H2 (trace), C2H4, CH4, C2H6 |
| Thermal faults in oil @over 700°C (T3) / Arcing | H2, C2H2, C2H4, CH4 |
| Partial Discharge (PD) | H2, C2H2 (trace), CH4 |
A valid strategy for condition-based maintenance is to apply fleet wide monitoring of hydrogen and apply monitoring of further key gases to critical transformers and conspicuous ones.
Optional Sensproduct integration provides easy accessibility of fleet data — the deck illustrates a fleet of transformers of different sizes each fitted with a SITRAM H2Guard Lite, with larger critical units additionally carrying a multi-gas DGA monitor, all reporting into the Sensproducts platform.
Benefits: reasonable for a wide range of transformers; enables fleetwide condition monitoring; long lifetime and maintenance free (thanks to the solid-state palladium alloy sensor), easy to install and remove.
Features: real-time hydrogen measurement in the transformer's liquid and headspace (head mounting for gas); historical evolution of hydrogen measurements; straightforward integration in monitoring systems.
Solid state measurement technology: the sensor measures directly in the insulation fluid or headspace. Palladium catalyzes H2 (molecule) to H (atoms); the absorbed hydrogen changes the alloy's ohmic resistance, which is the measurement basis. No membrane or other gas extraction method is needed, and the sensor requires no maintenance.
Robust design against shock, vibration, and water and dust ingress.
Accurate measurements over years of service: periodic reference cycles are automatically performed to guarantee long-term accuracy; the sensor is calibrated to measure hydrogen dissolved in insulation fluid or in headspace; no periodic manual calibration is needed.
Oil installation — use case: any transformer entirely filled by oil. Hydrogen is reported as ppm H2 dissolved in oil; the H2 sensor is able to monitor gas in oil and does not need to extract gas. The deck marks several suitable oil-mounting positions on a large power transformer.
Gas installation — use case: nitrogen blanketed transformers. Hydrogen is reported as in-oil-equivalent ppm H2; vertical or horizontal mounting is possible, with head mounting for gas shown on a distribution transformer. The H2 sensor is able to monitor gas in the headspace.
Mechanical details: rugged waterproof mechanical assembly design for various transformer applications; ¾"-14 NPT fitting for attaching the sensor to a transformer. The outline drawing dimensions the sensor at a 40 mm (1.56 in) square body cross-section and 151 mm (5.94 in) overall length, with the M12 4-wire connector at one end and the ¾-14 NPT process thread at the other.
Electrical connection: a 4-pin M12 connector carries both power and communications — DC power input (12 to 48 volts) at 10 watts, and 2-wire RS485 for Modbus RTU communications.
Measurement performance as printed on the slide. Fidelity note: the deck prints the operating temperature as '-20° to 105°' (no unit symbol printed); the companion SITRAM H2Guard Lite brochure frames temperature differently (ambient -40 °C…+70 °C, oil ≤ 105 °C) — both are transcribed as printed in their respective documents.
| Parameter | Value |
|---|---|
| Range | 25 – 5000 ppm |
| Accuracy | 20 % of reading or +/-25 ppm |
| Repeatability | 10 % of reading or +/-15 ppm |
| Cross-sensitivity | < 2 % to other gases CO, CO2, CH4, C2H2, C2H4, C2H6, C3H8, etc. |
| Operating temperature | -20° to 105° (no need for fin adaptor or other cooling methods) |
The deck's resources slide points to the Grid Technologies Service web page (siemens-energy.com/gt-service), the SITRAM Online Monitoring Devices download area on siemens-energy.com for documents, and customer technical support at support@siemens-energy.com.
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