Nexisense ZEH04 SF6 and Oxygen Dual Detection Module | Dual-Channel Simultaneous Monitoring, Strengthening Power and Industrial Gas Safety

High-voltage electrical equipment widely uses SF6 as insulation and arc-extinguishing gas. Its leakage not only affects equipment insulation performance but may also cause oxygen dilution in confined or semi-confined spaces leading to personnel asphyxiation risk. Traditional solutions require separate deployment of SF6 and oxygen sensors, resulting in complex layout, redundant interfaces, and high maintenance costs. The Nexisense ZEH04 module adopts NDIR infrared + electrochemical dual-sensor fusion architecture, achieving simultaneous, high-precision acquisition of SF6 concentration (ppm level) and oxygen volume fraction (%VOL) within a single module, providing efficient, integrated gas risk perception solutions for power systems, substations, and industrial process safety.

Dual Technology Fusion Principle and Environmental Adaptability Design

SF6 channel is based on non-dispersive infrared (NDIR) absorption spectroscopy: infrared light source emits broad-spectrum light, focused into the gas chamber after narrowband filter, SF6 molecules produce strong absorption in the 10.55–10.65μm band, causing transmitted light intensity attenuation. The detector collects the signal and converts concentration via Beer-Lambert law, achieving ppm-level resolution and long-term zero drift control.

Oxygen channel adopts limited diffusion electrochemical principle: oxygen molecules are reduced at the cathode to produce current, current proportional to oxygen partial pressure, output stable reading after temperature compensation and humidity correction. The module has built-in environmental sensors and algorithm compensation modules, maintaining SF6 channel zero drift <±3ppm/year and oxygen channel <±0.5%VOL/year within -20～+60℃, 0～95%RH (non-condensing), effectively suppressing water vapor, CO₂ background, and temperature cross-interference.

Core Performance Parameters and Engineering Reliability

• SF6 Measurement: Range 0～1000/1500/2000ppm optional, resolution 1ppm, accuracy ±3% reading or ±5ppm (whichever is greater), T90 response time<35s

• Oxygen Measurement: Range 0～25%VOL, resolution 0.1%VOL, accuracy ±1%FS, response time<20s

• Output Interface: UART (TTL 3.3V/5V, 9600/19200bps default), Modbus RTU protocol; optional 4–20mA current loop, relay contacts

• Power Supply: DC 5V±0.5V or 9～24V wide voltage, average power consumption<180mW

• Protection Rating: IP65 (diffusion type), optional higher protection or explosion-proof enclosure

• Expected Lifespan: NDIR channel >8 years, electrochemical oxygen channel >3 years (normal environment)

These indicators ensure the module meets relevant standards requirements such as DL/T 639-1997 and GB 12358 for power and industrial gas monitoring.

Typical Project Application Scenarios and Integration Value

High-Voltage Switchgear and Ring Main Unit Gas Monitoring

ZEH04 directly embedded in leakage-prone areas of the cabinet or installed at low position, SF6 concentration exceeding limit (typical 1000ppm level-1 alarm, 1500ppm level-2) triggers cabinet ventilation or trip interlock; oxygen below 19.5%VOL issues personnel entry prohibition warning, ensuring safety during live inspection and routine maintenance.

GIS Combined Apparatus Room and Substation Area Protection

Adopt multi-point distributed deployment (1–2 per bay or per room), access to station control layer SCADA system via RS485 bus or UART-to-Ethernet gateway, achieving real-time concentration map, historical trend curve, alarm event record, and remote push, compliant with smart substation gas online monitoring specifications.

Cable Tunnels, Underground Distribution Rooms, and Confined Space Operations

High-humidity, large temperature difference, weak airflow environments are typical advantageous scenarios for ZEH04: anti-water vapor algorithm + NDIR oxygen-independent characteristics ensure data stability, oxygen channel prioritizes hypoxia warning, SF6 channel captures early micro-leakage, supports linkage with ventilation control system for forced exhaust.

Chemical/Metallurgical/Semiconductor Process Gas Safety

When SF6 is used as tracer gas or process medium, ZEH04 provides dual-parameter redundant monitoring, integrated into PLC or safety instrumented system (SIS), realizing automatic valve shut-off, emergency ventilation start, and other safety interlock logic upon concentration exceeding limit.

Selection Guide: Core Parameters for Matching Project Requirements

• Range Selection: SF6 0～1000ppm (conventional leakage monitoring)/0～2000ppm (high-concentration warning); oxygen 0～25%VOL (hypoxia focus)

• Output Type: UART+Modbus (digital integration preferred), 4–20mA (traditional analog compatible), relay (independent alarm)

• Power Supply and Protection: 5V embedded / 24V industrial field; IP65 standard / Ex d IIC T6 Gb explosion-proof (when necessary)

• Installation Form: Diffusion type built-in / add sampling pump to improve response speed

• Alarm Strategy: Supports two-level thresholds (SF6 1000/1500ppm, O₂ 19.5%/18%), configurable remotely via Modbus

System Integration Notes and Engineering Practices

• Installation Position: SF6 probe preferably placed at low position below leakage point (density higher than air); oxygen monitoring combined with personnel frequent area height

• Gas Chamber Maintenance: Avoid condensate accumulation, recommend regular inspection of optical window cleanliness; high-humidity environment optional heating module

• Communication Configuration: Modbus address default 1, batch setting supported; polling cycle recommended 5～15s to avoid bus congestion

• Interlock Design: Alarm signal access to PLC high-speed input or safety relay, ensuring<1s response

• Calibration Cycle: Recommend annual zero point (clean air/nitrogen) + span (standard mixed gas), record drift trend

  
  

OEM Customization and Bulk Supply Capabilities

Nexisense provides customization support for system integrators and engineering projects:

• Range, accuracy grading, threshold preset adjustment

• Communication protocol extension (BACnet, Profibus, custom frame)

• Enclosure form (wall-mounted/embedded/pipeline type), explosion-proof rating upgrade, brand labeling

• Factory multi-point calibration report, batch consistency test, traceability management

• Long-term supply agreement, buffer inventory, emergency sample delivery

These services help customers shorten project verification cycles, unify supply chain standards, and meet different specification requirements.

Frequently Asked Questions

1. How does ZEH04's NDIR channel achieve high selectivity for SF6? Uses narrowband filter (CWL≈10.6μm, HBW<200nm) to precisely match SF6 strong absorption peak, effectively suppressing common interfering gases such as CO₂, H₂O, CH₄.

2. How is reading stability of oxygen channel ensured in high-humidity environments? Built-in humidity compensation algorithm + optimized electrolyte formula, oxygen zero drift <±0.3%VOL/year within 0～95%RH, meeting harsh scenarios such as underground tunnels.

3. What Modbus function codes and key registers does the module support? Supports 03 (read holding registers), 06 (write single register), 16 (write multiple registers); includes registers for real-time concentration, status, temperature, humidity, fault codes, etc.

4. How does SF6 detection T90 response time perform in actual leakage scenarios? Diffusion type<35s, adding micro-pump sampling can shorten to <15s, meeting DL/T 639 early warning time requirements.

5. What factors most affect electrochemical oxygen sensor lifespan? Mainly cumulative oxygen exposure and extreme temperature/humidity; normal air environment design life >3 years, module provides lifespan prediction register to assist maintenance planning.

6. How to avoid address conflicts and communication congestion when networking multiple modules? Supports address modification in 0～247 range, recommend master-slave polling mode, stable communication when single bus nodes<64 with="" interval="">5s.

7. What explosion-proof and protection rating customizations are supported? Standard IP65, customizable Ex d IIC T6 Gb flameproof or higher protection enclosure, suitable for Zone 1/Zone 2 hazardous areas.

8. How to determine if sensor needs replacement or calibration after long-term operation? Module has built-in self-diagnostic function, reports optical window contamination, signal intensity attenuation, or electrochemical current anomaly; recommend annual calibration, trigger maintenance reminder when drift exceeds ±5%.

Conclusion: Partner with Nexisense ZEH04 to Build a More Reliable Industrial Gas Safety System

Nexisense ZEH04 SF6 and oxygen dual detection module, with dual-channel fusion technology, strong environmental adaptability, and simple integration features, provides efficient gas risk closed-loop management for high-voltage electrical, substations, and industrial processes. It helps system integrators reduce total ownership costs, simplify deployment and maintenance, and improve project safety compliance levels.

Welcome power engineering companies, substation general contractors, industrial safety solution integrators to contact the Nexisense team for complete technical materials, prototype testing support, or project customization schemes. We look forward to cooperating with you to jointly safeguard every gas safety point in industrial sites.