Mining cables must comply with the earthing requirements, which stipulate that the earthing conductor's conductance must be at least 50 percent that of one of the power conductors.
FREMONT, CA: Electricity is used for a variety of functions throughout any mine, both below and above ground. The required electrical power is obtained from the colliery's generating station or, more commonly, from the local electricity supply via a substation.
It is common knowledge that underground cables in collieries must survive adverse conditions such as roof falls, moisture, and other possible sources of damage. As a result, mining cables must be built to endure the rigors of the job. Furthermore, they must be maintained regularly to ensure their safety and dependability. In fact, for efficient coal production, reliable and durable cables are critical.
Furthermore, these mining cables must comply with the earthing requirements, which stipulate that the earthing conductor's conductance must be at least 50 percent that of one of the power conductors. PVC/XLP insulated cables with metric dimensions are now utilized in mines for the major high and medium voltage distribution lines. Before the introduction of metric cable sizes, the same cables were used in inch sizes. The inch or imperial size wires are still in use today. Before introducing PVC insulated cables, the most popular form of cable was the paper-insulated lead sheathed type.
This type of cable is still in use in large quantities. There are cables with two to four cores or conductors available. Three core cables are typically used for three-phase A.C. distribution, one core for each phase of the supply system.
The cores are made up of the following components:
Plain Copper Wires: stranded conductor.
Pre-Formed Solid Aluminum Rod: Solid conductor.
Plain Aluminum Wires: Stranded conductor.
A conductor's cross-section is made up of a circle's sector. Individual cores are isolated by a colored PVC insulating material, with red, yellow, and blue being the colors of the three power cores. When using four core cables, the fourth core is neutral and colored with black insulating material.
The cable's conductors are twisted together in a spiral. Worming can be used to fill in any gaps between them, resulting in a uniform circular portion. A layer of tape is frequently used to join the assembled conductors. The laid-up cable is coated with bedding, which is an extruded PVC sheath to keep moisture out. Single-armored and double-armored cables are both available. Each armor layer is made up of galvanized steel wires spiraled along the cable.
A separator of compounded fibrous tape separates the two layers of armor in double armored cable, and the galvanized wires are spiraled in opposite directions. The armoring serves as the cable's earth conductor, making it crucial in terms of earthing.