DGA-900 — Laser Photoacoustic Spectroscopy Multi-Gas DGA Monitor
Laboratory-grade dissolved gas analysis in real time. 9 fault gases + moisture via patented Laser Photoacoustic Spectroscopy (LPAS). Deployed in China’s largest 1000 kV UHV substations and ±800 kV HVDC converter stations. The definitive online DGA solution for the world’s most critical power transformers.
Laser Photoacoustic Spectroscopy (LPAS)
15 fm spectral line width · Zero cross-interference · IEC 61850
The DGA-900 is a cutting-edge online Dissolved Gas Analysis (DGA) monitoring system powered by Laser Photoacoustic Spectroscopy (LPAS) — a technology that delivers the multi-gas analytical depth of laboratory gas chromatography with the real-time continuous monitoring of an online system. It detects and quantifies 9 fault gases plus moisture in transformer oil, providing the most complete picture of transformer health available in a single online instrument.
At the heart of the DGA-900 is a semiconductor laser with a spectral line width of just 15 femtometers (0.000015 nm). This ultra-narrow line width can be precisely aligned with the characteristic absorption spectral line of each target gas, achieving virtually zero cross-interference — a fundamental advantage over conventional broadband IR photoacoustic spectroscopy where optical filters cannot fully separate overlapping absorption bands.
The system employs a patented vacuum-assisted membrane extraction technology that efficiently extracts dissolved gases from transformer oil without oil consumption. The extracted gases enter a miniature photoacoustic cell (1 mL volume, patented design) where the modulated laser beam excites each gas species at its specific absorption wavelength. The resulting acoustic pressure waves — proportional to gas concentration — are detected by a high-sensitivity microphone.
The DGA-900 complies with IEEE C57.104 and IEC 60599 standards. Its embedded diagnostic engine runs Duval Triangle, Rogers Ratio, and Doernenburg Method analyses onboard, providing 72-hour early warning for incipient faults — enabling planned maintenance interventions before failures occur.
Key Specifications at a Glance
| Technology | Laser Photoacoustic Spectroscopy (LPAS) |
| Gas Detection | 9 gases + moisture |
| H₂ Range | 2 – 5,000 ppm (custom) |
| C₂H₂ Detection Limit | 0.1 ppm |
| Communication | IEC 61850, MODBUS RTU/TCP, IEC 104, DNP3.0 |
| Diagnostics | Duval Triangle, Rogers Ratio, Doernenburg |
| Oil Consumption | Zero (patented vacuum extraction) |
| Enclosure | IP55, 630×660×870 mm |
| Weight | <150 kg |
| Warranty | 3 Years (or 2,000 cycles) |
The DGA-900’s laser photoacoustic spectroscopy represents a fundamental advance over conventional broadband IR-based PAS systems. The difference is in the light source.
L-PAS: 15 fm Line Width
The semiconductor laser source has a spectral line width of 15 femtometers (0.000015 nm) — narrower than the absorption spectral lines of individual gas molecules. This means the laser can be precisely tuned to the exact absorption wavelength of each target gas without exciting neighboring gas species. The result: virtually zero cross-interference between gases, even for closely spaced absorption bands like C₂H₄ and C₂H₆.
Classic-PAS: Broadband Limitation
Conventional broadband IR-PAS uses a wide-spectrum infrared source with optical filters to select wavelength bands. Even the best optical filters have bandwidths of tens of nanometers — thousands of times wider than gas absorption lines. This causes inherent cross-interference between gases with overlapping absorption spectra, reducing accuracy and requiring complex compensation algorithms that drift over time.
The LPAS Advantage: 5 Key Benefits
1. Zero Cross-Interference — Laser precisely matches single gas absorption lines. No optical filter drift. No compensation needed.
2. Higher Sensitivity — Concentrated light energy at the target wavelength → stronger photoacoustic signal → lower detection limits (0.1 ppm for C₂H₂).
3. Superior Long-Term Stability — No optical filter degradation. Laser wavelength is inherently stable. Factory calibration holds for years.
4. Wider Dynamic Range — From trace (0.1 ppm) to fault-level concentrations (up to 200,000 ppm for N₂). Single instrument covers all DGA scenarios.
5. No Consumables — No carrier gas, no columns, no flame ionization detector. The laser source has a rated lifetime exceeding 10 years of continuous operation.
The DGA-900 detects and quantifies all key fault gases identified in IEC 60599 and IEEE C57.104, plus oxygen and nitrogen for complete oil condition assessment. Custom ranges available per customer requirements.
| Gas | Minimum Detection | Maximum Range | Accuracy | Repeatability | Fault Indication |
|---|---|---|---|---|---|
| H₂ — Hydrogen | 2 ppm | 5,000 ppm (custom) | ±8% | <3% | Partial discharge, arcing, thermal faults |
| O₂ — Oxygen | 200 ppm | 100,000 ppm (custom) | ±3% | <3% | Seal integrity, oil oxidation |
| CO — Carbon Monoxide | 20 ppm | 10,000 ppm | ±5% | <3% | Paper/cellulose thermal degradation |
| CO₂ — Carbon Dioxide | 20 ppm | 10,000 ppm | ±5% | <3% | Paper/cellulose thermal degradation |
| CH₄ — Methane | 0.5 ppm | 10,000 ppm | ±8% | <3% | Oil thermal fault (low-temp hot spot) |
| C₂H₂ — Acetylene | 0.1 ppm | 10,000 ppm | ±5% | <3% | Arcing (key gas — most critical indicator) |
| C₂H₄ — Ethylene | 0.5 ppm | 10,000 ppm | ±8% | <3% | Oil thermal fault (high-temp hot spot) |
| C₂H₆ — Ethane | 0.5 ppm | 10,000 ppm | ±8% | <3% | Oil thermal fault (medium-temp) |
| N₂ — Nitrogen | 1,000 ppm | 200,000 ppm | ±3% | <3% | Inert gas blanket integrity |
| H₂O — Moisture | 0–100% AW / 0–100 ppm | — | ±3% | <3% | Seal integrity, oil quality |
The DGA-900 is available in three configurations tailored to different deployment scenarios and integration requirements. From OEM module supply to fully integrated turnkey systems.
Module Only
For system integrators and monitoring platform manufacturers. You provide the enclosure and assembly — we provide the LPAS core.
- LPAS degassing module (patented vacuum-assisted)
- Full 9-gas + moisture detection module
- Photoacoustic cell (1 mL, patented)
- Semiconductor laser source (patented)
- Communication module (IEC 61850 / MODBUS / IEC 104 / DNP3.0)
- PC debugging software + control room client software
- Enclosure drawings + assembly guidelines (free)
- Factory test report for each module
- OEM/ODM branding — no Haomai logo
Standard System
Turnkey solution for substation deployment. Fully assembled, factory-tested, and calibrated. Ready to connect to transformer oil valve and power.
- Everything in Module Only, plus:
- IP55 weatherproof enclosure (630×660×870 mm)
- Integrated air conditioning for enclosure
- Full installation and commissioning support
- 4-tier hierarchical alarm system
- Advanced data management software suite
- Multi-format data export (Excel, CSV, PDF)
- Automatic scheduled data logging
- Bidirectional remote communication
- On-site service available
Premium System
For the most critical assets — UHV substations, nuclear power plants, and HVDC converter stations — with extended warranty and premium support.
- Everything in Standard System, plus:
- Automatic cloud synchronization option
- Extended warranty (3+ years, up to 2,000 cycles)
- Priority on-site service (USD 80/person/day)
- Custom gas range calibration
- Dual redundant communication paths
- Enhanced cybersecurity package
- Dedicated technical account manager
- Quarterly health check reports
- Free software updates for life
The DGA-900 includes a comprehensive PC software package for configuration, monitoring, and diagnostic analysis — all running on standard Windows workstations in the control room.
Individual Gas Parameterization
Custom alarm thresholds, measurement ranges, and sampling intervals for each gas species. Configure H₂, CH₄, C₂H₄, C₂H₂, C₂H₆, CO, CO₂, O₂, N₂, and H₂O independently.
Embedded Fault Analysis Engines
Duval Triangle 1 (IEC 60599), Rogers Ratio 3D visualization, and Doernenburg Method — all running onboard. Dynamic gas ratio trend plotting with configurable time windows.
Enterprise Data Management
Unlimited historical data storage with automatic cloud sync option. Export to Microsoft Excel (formatted templates), CSV for SCADA, clipboard copy/paste, and printer-ready PDF reports.
4-Tier Alarm System
Attention (50% threshold) → Warning (80%) → Critical (100%) → Emergency (120%). Each tier configurable per gas with independent notification actions — email, SMS, relay, SCADA alarm.
Bidirectional Communication
Local and remote operation via IEC 61850 MMS/GOOSE, MODBUS RTU/TCP, IEC 60870-5-104 (IEC104), DNP3.0, and RS-485 (up to 1 Mbps, 32-node daisy chain).
Automated Scheduled Logging
Configure automated measurement schedules — from continuous sub-minute sampling during fault conditions to hourly logging during steady-state operation. All data timestamped and stored.
Measurement System
| Technology | Laser Photoacoustic Spectroscopy (LPAS) |
| Laser Line Width | 15 fm (0.000015 nm) |
| Degassing | Patented vacuum-assisted membrane (zero oil consumption) |
| Photoacoustic Cell | 1 mL volume (patented) |
| Gases Detected | H₂, O₂, CO, CO₂, CH₄, C₂H₂, C₂H₄, C₂H₆, N₂, H₂O |
| Measurement Accuracy | Min detection limit or ±20% (whichever is greater) |
| Sampling Interval | Configurable, 1 min minimum |
| Oil Temperature Range | 10 to 100°C |
System & Environmental
| Power Supply | AC 210–240V, 50/60 Hz, 2 kW |
| Ambient Temperature | -40 to 55°C (-10 to 55°C when starting) |
| Humidity | 10–95% RH, non-condensing |
| Enclosure Rating | IP55 |
| Dimensions | 630 (W) × 660 (D) × 870 (H) mm |
| Weight | <150 kg |
| Communication | IEC 61850, MODBUS RTU/TCP, IEC 104, DNP3.0, RS-485/232 |
| Warranty | 3 years or 2,000 cycles (whichever first) |
The DGA-900 (PASL-3000) is deployed across China’s most critical power infrastructure — from 1000 kV UHV AC substations to ±800 kV HVDC converter stations, nuclear power plants, and major hydropower facilities.
Nuclear Power
Dalian Hongyanhe Nuclear Power Plant — continuous DGA for critical GSU and station service transformers.
1000 kV UHV AC
Jiangxi Ganjiang, Shanxi Beiyue, Shandong Gaoxiang, Shanxi Changzhi, Jingmen — China’s UHV backbone.
±800 kV HVDC
Wuhan Converter Station, Ningxia Lingzhou, Gansu Qilian, Gusu, Hubei Daye — converter transformer monitoring.
Hydropower Plants
Jiangxi Wan’an, Hunan Dongjiang — GSU transformer monitoring at major hydroelectric stations.
750 kV Substations
Gansu Jiuquan Shazhou, Gansu Dingxi Lanlin, Gansu Hexi — Northwest China grid backbone.
500 kV Regional Grid
Huizhou Goose City, Hubei Mulan, Liaoning Dandong — regional transmission hub substations.
When to Choose Hydrogen Sensors
The PAS DGA hydrogen sensor series (DGA-200/300/500) is ideal for fleet-wide deployment — distribution transformers, industrial plants, and any application where hydrogen trending alone provides sufficient early warning. Lower acquisition cost, zero maintenance, valve-mount installation in under an hour. Hydrogen is the universal fault indicator — it’s generated in every transformer fault type. For the majority of transformers, hydrogen monitoring provides the highest diagnostic value per dollar.
When to Choose DGA-900
The DGA-900 is the choice for critical assets where comprehensive diagnostics are mandatory — transmission-class transformers (≥220 kV), GSU transformers at power plants, HVDC converter transformers, and nuclear facility transformers. When you need full gas speciation for precise fault type identification (thermal vs. electrical, oil vs. paper involvement), or when regulatory/compliance requirements mandate multi-gas DGA, the DGA-900 delivers laboratory-grade analysis in real time.
How PAS Works
Pd Thin-Film Sensor Technology
DGA Technology Comparison
DGA Fundamentals
DGA Diagnostic Methods
Fault Types & Gas Signatures
Hydrogen vs Multi-Gas DGA
Online vs Offline DGA
Duval Triangle Method
DGA Standards & Certifications
Power Utility Applications
HVDC & UHV Applications
Industrial Applications
Technical Datasheets
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