Explosion-proof dual power switch for local ventilation fans in coal mines
1Key Takeaways
This standard specifies the requirements for explosion-proof dual power transfer switches used in local ventilation fans within coal mines. It ensures safe operation and reliability by detailing technical specifications, testing methods, and performance criteria for these switches. The standard is designed to address …
2Expert Interpretation
In-depth analysis of the NB/T 11631-2024 explosion-proof dual power transfer switch standard for local ventilation fans in coal mines, covering technical parameters, explosion-proof requirements, test methods and inspection rules, and providing selection and installation guidance for mining electrical appliances with rated voltage below 1140V.
Interpretation of the core content of the standard
The NB/T 11631-2024 standard specifies the technical requirements and safety specifications for explosion-proof dual power transfer switches for the special environment of underground coal mines. It is applicable to local fan control systems with AC 50Hz and voltage 1140V and below.
Key Technical Parameters
| Parameter Category | Technical Requirements | Typical Value |
|---|---|---|
| Rated Voltage | Main Circuit Operating Voltage | 380V/660V/1140V |
| Rated Current | Grading Standard | 80A-630A, 9 Levels |
| Protection Grade | Shell Protection | ≥IP54 |
| Surface Temperature | Explosion-proof Requirements | ≤150℃ |
Explosion-proof structure requirements
The standard strictly stipulates that the flameproof enclosure must comply with the requirements of the GB/T 3836 series:
- Material requirements: Steel or cast steel enclosure, the flameproof surface parameters must meet GB/T 3836.2-2021
- Structural verification: Pass static pressure test (≥1.5 times reference pressure), pressure test (1.5 times explosion pressure)
- Special treatment: The flameproof surface is coated with anti-rust oil, and non-metallic materials must pass the chemical reagent resistance test
Protection function comparison
| Protection type | Communication switch | Communication control switch |
|---|---|---|
| Basic protection | Overvoltage/undervoltage/leakage lockout | Add overload/phase loss/short circuit protection |
| Locking function | Wind power methane electric lockout | Mechanical and electrical double interlock |
| Response time | Short circuit protection 200-400ms | Including the disconnection time of the upper switch |
Implementation suggestions
Selection precautions
- Select the corresponding current level according to the fan power (it is recommended to leave a 20% margin)
- High-gas mines give priority to flameproof and intrinsically safe products
- Confirm the integrity of the warning label on the protective cover
Installation and maintenance points
- The installation inclination should be ≤15°, and avoid severe vibration
- Regularly check the anti-rust condition of the flameproof surface (cycle ≤3 months)
- The functional test must include a simulated power switching test