I. Prevention during the selection and procurement stage
Select high-reliability products: Prioritize intrinsically safe sensors with Ex ib 1 Mb or equivalent explosion-proof certification, ensuring they pass rigorous aging tests and sealing inspections before leaving the factory.
Request factory test reports: Obtain calibration data and durability test records for each batch from the manufacturer to avoid using unverified "problematic components."
Match operating parameters: Select appropriate materials (e.g., 316L stainless steel protective tubes) and temperature measurement methods (PT100 is superior to thermocouples for stability) based on the on-site temperature range, vibration intensity, and type of corrosive gases.
II. Risk control during installation
Avoid live work: Never connect or disassemble wires while the power is on to prevent electrical sparks from igniting ambient gases and to avoid reverse connection damage to internal circuitry.
Use Intrinsically Safe Cables: Utilize intrinsically safe shielded cables such as MHYVP for mining, with a cross-sectional area ≥1.5mm², ensuring transmission parameters meet safety limits of U₂≤18V and I₂≤80mA.
Standardized Grounding and Shielding: The shielding layer is grounded only at one end on the control room side to avoid ground loops and interference, improving electromagnetic interference immunity.
Tight Sealing and Intrusion Prevention: Use explosion-proof glands to tighten the cable inlet; seal any excess connections with plugs to prevent gas and moisture from entering the wiring cavity.
III. Maintenance and Prevention During Operation:
Regular Cleaning and Maintenance: Clean the probe and protective tube surface monthly to remove coal dust and oil stains, preventing increased thermal resistance and lower temperature readings. In humid environments, check junction boxes for condensation.
Periodic Calibration:
It is recommended to calibrate quarterly in underground coal mines using a standard Pt100 or infrared meter. Adjustments or replacements are required if the deviation exceeds ±0.5℃. Intelligent sensors supporting in-situ self-calibration (such as the TrustSens series) can be used to automatically complete calibration during high-temperature cycling, reducing the risk of disassembly.
Connection Status Inspection: Check for loose or oxidized terminals, and for worn or compressed cables. Tighten or replace any abnormalities promptly to prevent signal interruption due to poor contact.
Environmental Adaptability Protection:
Install protective covers to prevent water damage and mechanical impact; use thermal insulation sleeves in high-temperature areas to prevent thermal grease from drying out and affecting response speed; use armored sensors for vibration equipment to improve fatigue resistance.
IV. System-Level Safety Assurance:
Safety Barrier Status Monitoring: Regularly check the grounding resistance and voltage limiting function of Zener or isolation safety barriers to ensure they are always in an effective protective state.
Cable Laying Isolation: Intrinsically safe lines should be run in separate conduits from power cables, with a distance of ≥30cm, to prevent induced voltage from exceeding the safe energy threshold.
Maintenance Record Establishment: Record the time and results of each cleaning, calibration, and replacement to achieve full lifecycle traceability management.
