Hydrogen Sensors — Pd Alloy Thin-Film DGA Monitors & OEM Probes
Proprietary palladium (Pd) alloy thin-film hydrogen sensing in a solid-state element immersed directly in the transformer oil. Unlike electrochemical sensors that degrade over time or gas chromatography that requires consumables, these sensors provide maintenance-free operation for 10 years with no routine calibration required.
Technology That Eliminates Maintenance
Pd Alloy Thin-Film
A palladium alloy thin film sits directly in the transformer oil — no membrane and no oil-gas separation. Measurement is unaffected by vacuum or positive pressure.
Zero Consumables
No carrier gas, no oil-gas separation membrane and no sensor replacement — nothing to change out on a maintenance cycle.
2 ppm Detection
The DGA-300 palladium alloy MOSFET chip resolves dissolved hydrogen down to 2 ppm, measured in the oil itself with no oil-gas separation.
Rugged & Rated
The DGA-200 is a wall-mount unit with a rain cover, rated IP66; the DGA-300 and DGA-500 mount directly on the transformer, rated IP67.
Flexible Comms
All three models use RS-485 / MODBUS RTU. The DGA-200 monitoring unit adds three 4–20 mA analog outputs and three relay outputs.
10-Year Life
Expected sensor life is 10 years with no periodic maintenance — no separation membrane, no carrier gas, no sensor replacement. Readings are field-verifiable against ASTM D3612 offline DGA, with recalibration only if the deviation exceeds 15%.
Model Comparison
| Specification | DGA-300 | DGA-500 | DGA-200 |
|---|---|---|---|
| Role | Embedded sensor for multi-gas DGA systems | Standalone sensor on the transformer | Integrated monitoring unit |
| H₂ Range | 2 ~ 2000 ppm | 5 ~ 5000 ppm | 5 ~ 5000 ppm |
| Detection Limit | 2 ppm | 5 ppm | Not specified |
| Accuracy | ±20% or ±2 ppm | ±15% or ±5 ppm | ±15% or ±5 ppm |
| Applicable Oil Temp. | 0 ~ 60 ℃ | −40 ~ 105 ℃ | −40 ~ 105 ℃ |
| Communication | RS-485 / MODBUS RTU | RS-485 / MODBUS RTU | RS-485 / MODBUS RTU + 3 × 4–20 mA + 3 relays |
| Power | 24 V DC, 0.3 A (max) | 24 V DC, 0.3 A (max) | 24 V DC, 0.5 A (max) |
| Rating | IP67 | IP67 | IP66 |
| Weight | ≤ 350 g | ≤ 500 g | approx. 1.75 kg |
| Best For | OEM integration | Standalone transformer mounting | Distribution transformer fleets |
Model Deep-Dive
OEM Sensor for Multi-Gas DGA Systems
DGA-300
The DGA-300 is designed to be embedded in a multi-gas DGA on-line monitoring system as its hydrogen measurement element. Its palladium alloy MOSFET chip sits directly in the transformer oil — no oil-gas separation — and resolves hydrogen down to 2 ppm across a 2 ~ 2000 ppm range. RS-485 / MODBUS RTU output, 0 ~ 60 ℃ applicable oil temperature, IP67.
Standalone Transformer Sensor
DGA-500
The DGA-500 mounts independently on the transformer body and installs directly at the transformer ball valve, with IP67 protection and a −40 ~ 105 ℃ applicable oil temperature for long-term outdoor service. It measures dissolved hydrogen from 5 to 5,000 ppm and can be supplied with an optional moisture sensor and an optional oil pressure sensor (0 ~ 1 MPa).
Integrated Monitoring Unit
DGA-200
The DGA-200 is a wall-mounted unit with a rain cover that monitors dissolved hydrogen, moisture and oil temperature at the sampling valve of oil-filled equipment. It carries its own RS-485 / MODBUS RTU output, three 4–20 mA channels, three relay outputs and three status LEDs, with an optional LED panel — no separate transmitter is needed.
Applications
Distribution Networks
Fleet-wide hydrogen monitoring on distribution transformers. Valve-mount, zero maintenance, budget-friendly coverage of every unit.
Transmission & Substations
Early warning on critical feeders and substation transformers, with MODBUS RTU (RS-485) output into station SCADA.
Industrial & Mining
Arc furnace, rectifier, and process transformers. IP66 rugged design withstands vibration, dust, and harsh environments.
Renewable Energy
Wind, solar, and BESS step-up transformers at remote, unmanned sites.
Interested in the Hydrogen Sensor Family?
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Explore DGA Technology & Applications
Pd Thin-Film Sensor Deep-Dive
In-Situ Hydrogen Sensing Deep-Dive
Hydrogen vs Multi-Gas DGA
Online vs Offline DGA
DGA Fundamentals
DGA Diagnostic Methods
Fault Types & Gas Signatures
DGA Technology Comparison
Power Utility Applications
Renewable Energy Applications
Image credits: Wikimedia Commons (CC BY-SA) — placeholder photography. Product photographs and detailed specifications available on request.