Mining cables represent coal mine cables. Mining cables are flame-retardant cables, and all must obtain a mining product safety certificate from the National Center for Standardization and Safety.
As we mentioned, mining cables are flame-retardant cables, and we've discussed their flame-retardant mechanism. Flame retardants are added to the insulation and sheathing materials of mining cables. The heat of the combustion reaction is in the condensation phase. The flame retardants decompose and absorb heat, slowing the temperature rise of the condensation phase and the rate of pyrolysis.
What types of mining cables are there?
According to the industry standard "Flame-Retardant Cables for Coal Mines" issued by the State Administration of Coal Industry, the designations of mining cables, or mining cable models, are as follows:
The cable name consists of eight parts.
The first part is the series code, M, which is the pinyin initials of the Chinese character for "coal."
The second part is the usage characteristic code, which reflects the application in which the cable is used. The letters represent the following: C, for coal mining machines; D, for low-temperature environments; M, for cap lamps; Y, for mobile coal mining equipment; and Z, for electric drills.
The third part is the structural characteristic code, which indicates the cable's structural characteristics. The letters mean as follows: B, braided reinforcement; J, with monitoring core; P, non-metallic shield; PT, metallic shield; Q, lightweight; R, wrap reinforcement.
The fourth section is the material characteristic code, with E indicating that the insulation or sheath is made of an elastomeric material. This section is omitted if both the insulation and sheath are made of rubber. E, elastomeric material.
The fifth section is the rated voltage U0/U (KV).
The sixth section represents the number of power conductor cores * nominal cross-sectional area. The two are connected by a multiplication sign, and the unit is square millimeters.
The seventh section represents the number of ground conductor cores * nominal cross-sectional area. The two are connected by a multiplication sign, and the unit is square millimeters.
The eighth section represents the number of auxiliary conductor cores * nominal cross-sectional area. The two are connected by a multiplication sign, and the unit is square millimeters.
The fourth and fifth sections are connected by a "-"; the sixth, seventh, and eighth sections are connected by a "+".
What are the designations for mining cables?
Products are identified by model, specification, and standard number.
1) Coal mining machine shielded rubber-sheathed flexible cable, rated voltage 0.66/1.14 kV, power conductor core 3*50, ground conductor core 1*10, control conductor core 4*4, with semi-conductive shield layer. Specified as: MCP-0.66/1.14 3*50+1*10+4*4 MT818.2-1999
2) Coal mining machine shielded monitoring braided reinforced rubber-sheathed flexible cable, rated voltage 0.66/1.14 kV, power conductor core 3*50, ground conductor core 1*25, control conductor core 2*2.5, with semi-conductive shield layer, monitoring conductor core, and braided reinforcement layer. Specified as: MCPJB-0.66/1.14 3*50+1*25+2*2.5 MT818.3-1999
3) Coal mining machine metal shielded monitoring rubber-sheathed flexible cable, rated voltage 0.66/1.14 kV, power conductor 3*70, ground conductor 1*25, monitoring conductor 1*35, with metal shield, designated as MCPTJ-0.66/1.14 (3*70+1*35+1*35), MT 818.4-1999
4) Mobile elastomeric flexible cable for coal mines, rated voltage 0.38/0.66 kV, power conductor 3*25, ground conductor 1*16, unshielded, designated as MYE-0.38/0.66 (3*25+1*16), MT818.5-1999
5) Mobile metal shielded monitoring rubber-sheathed flexible cable for coal mines, rated voltage 3.6/6 kV, power conductor 3*35, ground conductor 3*16/3, monitoring conductor 3*2.5, with semi-conductive shield, designated as MYPTJ-3.6/6 3*35+3*16/3+3*2.5 MT818.6-1999
6) Mobile shielded rubber-sheathed flexible cable for coal mines, rated voltage 3.6/6 kV, power conductor 3*25, ground conductor 1*16, for low-temperature environments, with semi-conductive shield, designated: MYDP-3.6/6 3*25+1*16 MT818.7-1999
7) Shielded elastomer cable for electric drills in coal mines, rated voltage 0.3/0.5 kV, power conductor 3*4, ground conductor 1*4, designated: MZPE-0.3/0.5 3*4+1*4 MT818.8-1999
8) Mobile lightweight rubber-sheathed flexible cable for coal mines, rated voltage 0.3/0.5 kV, insulated conductor 3*2.5, unshielded, designated: MYQ-0.3/0.5 3*2.5 MT818.9-1999
9) Coal Mine Miner's Cap Lamp Cable, Insulated Core 2*0.75, Expressed as: MM 2*0.75 MT818.10-1999
The above mining cable model numbers refer to those specified in MT818. According to the national standard GB12972, the series code is U, which is the second letter of the pinyin for "mining," as the first letter "K" is already occupied by control cables. The remaining codes are essentially the same.
When flame retardants decompose under heat, chain reaction free radicals are released, interrupting and slowing flame branching and chain reactions. This reduces the gas phase reaction rate; the catalytic condensation and thermal decomposition of solid phase products, leading to the formation of a caulking or foam layer, enhances the effect of these layered crusts on heat transfer. Grounding prevents temperature increases during the condensation step.
