Industry: Power industry

Online monitoring solution for SF6 gas leakage in power substations

Infrared SF6 online monitoring, coupled with oxygen content monitoring, facilitates a two-tiered alert system - early warning and emergency response

Industry Pain Points

SF6 is the core insulating medium for GIS equipment (circuit breakers/transformers/busbars) in substations of 110kV and above. However, as a potent greenhouse gas (GWP 23900), its leakage can trigger several consequences simultaneously: ① equipment insulation failure leading to tripping and widespread power outages; ② oxygen deficiency risks (SF6 is five times heavier than air, accumulating in low-lying areas and causing asphyxiation of maintenance personnel); ③ highly toxic arc decomposition products such as SO2/HF/SOF2 (PC-STEL limit is only 5 ppm). Traditional manual inspections conducted once a month are insufficient to detect leaks, and leakage rates exceeding 1% per year (the national standard limit) can result in equipment overhaul, regulatory penalties, and carbon emission disclosure issues. Unmanned substations, newly built UHV stations, and smart substations have a strong demand for online monitoring

Solution Overview

Yourui'an provides a full lifecycle monitoring solution for substation SF6: ① Fixed SF6 infrared/laser online monitors (accuracy < 0.1 ppm, response < 5 seconds), with 2-4 points per GIS bay; ② Multi-gas combined monitoring of SF6 decomposition products (SO2/HF), for early warning of internal arc faults; ③ Oxygen deficiency alarms (O2 1% linked to power outage for maintenance). The equipment complies with GB/T 8905-2012 + DL/T 596-2021 + Q/CSG 1204001-2014. Optional IoT wireless sensors (without damaging the GIS tank), video linkage (leak point location), and mobile inspection PDA + infrared thermal imaging are available.

## Recommended Locations

– **GIS room**: 1 point each at the top and bottom of each compartment, covering the SF6 deposition area that is heavier than air
– **SF6 gas cylinder storage room**: 6m² with at least one point equipped with O2 monitoring
– **GIS Maintenance Channel**: Portable 4-in-1 Inspection Instrument for SF6, O2, and Decomposition Products
– **SF6 recovery device**: real-time monitoring of flow rate + purity (including micro-water content + oxygen content)

## Key Technical Parameters

– Range: SF6 0-1000 ppm (ambient) / 0-100% Vol (high concentration)
– Accuracy: ≤ ±5% F.S
– Response time: T90 < 30 seconds
– Operating temperature: -25℃ ~ +55℃ (required for outdoor stations)
– Protection level: IP65 (indoor) / IP66 (outdoor)

## Implementation Essentials

1. **Automatic Leak Rate Calculation**: The monitoring platform calculates ppmv/year based on the tank volume and concentration changes, and provides early warning according to the IEC 60376 threshold
2. **Oxygen Deficiency Risk Interlock**: O2 < 19.5% → Emergency Ventilation + Access Control Lockout + SMS Notification to Duty Personnel
3. **Decomposition Product Warning**: Simultaneous increase in SO2 + HF → Early signal of internal arc fault → Immediately check the internal status of GIS
4. **Carbon Emission Disclosure**: Annual data can be directly integrated with GHG Protocol reports, meeting ESG disclosure requirements

## Regulatory Basis

– GB/T 8905-2012 "Guidelines for Management and Detection of Gases in SF6 Electrical Equipment"
– DL/T 596-2021 "Preventive Testing Procedures for Power Equipment"
– Q/CSG 1204001-2014 China Southern Power Grid Enterprise Standard
– GB/T 11023-2018 High-Voltage Switchgear – SF6 Gas Sealing Test
– GB 50016-2014 Code for Fire Protection Design of Buildings (Ventilation Requirements for GIS Rooms)

## Applicable Customers

State Grid / China Southern Power Grid 220kV / 500kV / 1000kV substations, wind power / photovoltaic booster stations, new energy aggregation stations, urban distribution stations, rail transit main transformers, and enterprise-owned substations.

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