Rubber sheathed cable vulcanized hot patch tape for coal mines Part 1: Rubber insulated vulcanized hot patch tape
1Key Takeaways
This standard specifies the code, model specifications, technical requirements, test methods, inspection rules, packaging, marking, transportation and storage of rubber-insulated vulcanized hot-patch tapes for rubber-sheathed cables used in coal mines (hereinafter referred to as hot-patch tapes). This standard applies …
2Expert Interpretation
An in-depth interpretation of the MT 848.1-2000 industry standard for rubber-insulated vulcanized hot-patch tapes for rubber-sheathed cables for use in coal mines, covering product classification, technical indicators, test methods and inspection rules, and analyzing the application specifications and safety requirements of vulcanized hot-patch tapes in 1140V and 6000V cable repairs.
Standard Background and Industry Demand
This standard unified the technical specifications of rubber-insulated vulcanized hot-patch tape for rubber-sheathed cables used in coal mines for the first time, solving the problem of hundreds of domestic enterprises without unified standards at that time. It was formulated in accordance with the requirements of Document No. 401 of the Ministry of Coal Industry in 1994, filling the gap in the industry.
Core Parameters Comparison
| Indicators | MXRJ type (1140V) | MXRJG type (6000V) |
|---|---|---|
| Tensile strength | ≥5.0MPa | ≥6.5MPa |
| Elongation at break | ≥250% | ≥200% |
| Volume resistivity | ≥2×10¹³Ω·cm | ≥6.5×10¹⁴Ω·cm |
| Hot extension deformation | ≤20% | ≤15% |
Key technical requirements
5.1 Appearance quality control
It is stipulated that a mesh pattern is allowed on the surface of the hot patch tape, but the number of rubber lumps with a diameter of >0.5mm shall not exceed 2 per 100cm² to ensure the tightness of the repair interface.
5.3.6 Key indicators of electrical performance
- Breakdown voltage strength: ≥20kV/mm
- Dielectric loss tangent (MXRJG): ≤0.035
- Dielectric constant (MXRJG): ≤4.5
Details of test method
6.4.2 Air box aging test
The MXRJ type needs to be at (80±2)℃ for 240 hours, while the high-voltage MXRJG type requires (135±2)℃ for 168 hours, simulating long-term high temperature conditions.
6.4.5 Thermal extension test
MXRJG type needs to withstand a high temperature test of 250±3℃, 50℃ higher than the conventional type, to verify the ability to resist deformation under high pressure environment.
Implementation suggestions
- Selection basis: MXRJG series must be selected for 6000V high voltage environment, and its volume resistivity is one order of magnitude higher
- Storage specification: Maintain an environment of 0-30℃, more than 1 meter away from heat sources, and avoid direct sunlight
- Quality traceability: The packaging must include the inspection certificate number and manufacturing batch number, and the validity period monitoring