SANS Type 633 / 633-ECC 19/33 kV Mining Cables Mynkabel

Introduction

The backbone of any successful mining operation lies in its electrical infrastructure, and at the heart of this infrastructure are the cables that power the massive machinery that extracts South Africa's mineral wealth. The SANS Type 633 and 633-ECC 19/33 kV mining cables represent a pinnacle of engineering designed specifically to withstand the harsh, demanding conditions found in mining environments across the country.

These medium-voltage cables are not merely conductors of electricity; they are lifelines that ensure continuous operation of critical mining equipment whilst maintaining the highest safety standards for workers. In an industry where downtime translates directly to substantial financial losses and where worker safety is paramount, the reliability and durability of electrical cables cannot be overstated.

The SANS Type 633 series cables are engineered to meet the stringent requirements of South African National Standards (SANS), ensuring they can handle the unique challenges presented by the country's diverse mining landscape, from the deep gold mines of the Witwatersrand to the vast open-pit operations in the Northern Cape. Understanding these cables' capabilities, applications, and characteristics is essential for mining engineers, electrical contractors, and safety professionals working in the industry.

Application Scenarios: Where These Cables Prove Their Worth

Mining Operations: The Primary Domain

The SANS Type 633/633-ECC cables find their most demanding applications in South Africa's extensive mining operations, where they serve as the electrical arteries powering the industry's most critical equipment.

In open-cast mining operations, these cables excel in connecting draglines, electric rope shovels, and rotary drills to the electrical supply network. The cables' robust construction allows them to withstand the constant movement and mechanical stress associated with these mobile machines. When a dragline swings its massive bucket to extract overburden, or when an electric shovel repositions itself to load trucks with ore, the cable must flex and move without compromising electrical integrity or safety.

Underground mining presents even greater challenges, where the cables must navigate through confined spaces whilst maintaining their performance characteristics. Here, the SANS Type 633 cables power continuous miners, longwall shearers, and conveyor systems that transport ore from the working face to the surface. The cables' resistance to oil, chemicals, and abrasion becomes particularly crucial in these environments where hydraulic fluids and cutting oils are commonplace.

The flexibility characteristics of these cables make them particularly suitable for reeling drum applications. In many mining operations, equipment must be repositioned frequently to access different working areas. Cables stored on reeling drums can be extended and retracted as needed, providing power to mobile equipment whilst protecting the cable from damage during storage and deployment.

Portable and movable electric apparatus in hazardous zones represents another critical application area. In areas where explosive gases or dust may be present, the triple-screened design and robust construction of SANS Type 633 cables provide an additional layer of safety, ensuring that electrical faults do not become ignition sources.

Industrial Applications Beyond Mining

Whilst mining remains the primary application, SANS Type 633 cables also serve important roles in other industrial settings. They function effectively as section feeders in medium-voltage distribution networks, particularly in industrial facilities where reliability and durability are essential.

Manufacturing plants, particularly those involved in mineral processing, benefit from these cables' resistance to chemical exposure and mechanical stress. The cables can withstand the vibrations and environmental challenges present in crushing, grinding, and separation facilities that process mined materials.

In power generation facilities, particularly those serving mining operations, these cables provide reliable connections between generators, transformers, and distribution equipment. Their ability to handle fault currents safely makes them valuable in applications where electrical disturbances may occur.

Electrical Parameters and Mechanical Characteristics: The Technical Foundation

Voltage Rating and Electrical Design

The designation 19/33 kV refers to the cable's voltage rating system, where 19 kV represents the maximum voltage between any conductor and earth (Uo), whilst 33 kV represents the maximum voltage between conductors (U). This rating system follows international standards and ensures compatibility with South African electrical systems.

This voltage rating makes the cables suitable for medium-voltage distribution systems commonly found in mining operations. The voltage level provides an optimal balance between power transmission capability and safety considerations, allowing substantial power to be delivered to large mining equipment whilst maintaining manageable insulation requirements.

The cables are designed to operate continuously at these voltage levels whilst maintaining their insulation integrity and safety characteristics. The voltage rating includes appropriate safety margins to account for system overvoltages that may occur during switching operations or fault conditions.

Temperature Performance Characteristics

Operating temperature range represents a critical specification for mining cables, and the SANS Type 633 series performs reliably across a temperature span from -25°C to +90°C. This wide temperature range ensures functionality in diverse South African climates, from the cold winter conditions in high-altitude mining areas to the extreme heat encountered in deep underground workings.

The lower temperature limit of -25°C ensures that cables remain flexible and maintain their mechanical properties even during cold Highveld winters. The insulation materials retain their dielectric properties, preventing cracking or brittleness that could lead to electrical failures.

At the upper limit of +90°C, the cable materials maintain their integrity without degradation. This temperature capability is particularly important in underground mining where geothermal heating can create elevated ambient temperatures, or when cables are subjected to high electrical loads that generate internal heating.

Construction Details: Engineering for Durability

The conductor design utilises Class 5 flexible stranded tinned annealed copper, representing the optimal balance between conductivity, flexibility, and corrosion resistance. The tinning process provides protection against oxidation whilst maintaining the copper's excellent electrical conductivity. The Class 5 flexibility rating ensures the conductor can withstand repeated bending cycles without fatigue failure.

Conductor sizes range from 25mm² to 120mm², providing options to match various power requirements. The current-carrying capacity ranges from 105 amperes for the smallest conductor to 260 amperes for the largest, accommodating equipment from smaller auxiliary systems to main drive motors for large mining machinery.

The insulation system employs EPR (Ethylene Propylene Rubber) with a semi-conducting screen in a triple-extruded construction. This thermosetting compound provides excellent dielectric properties whilst maintaining flexibility across the operating temperature range. The semi-conducting screen ensures uniform electric field distribution around the conductor, preventing corona discharge and extending cable life.

Each power core receives individual screening using tinned copper and textile braid. This screening system provides protection against electromagnetic interference whilst offering a path for fault currents. The screening resistance values range from 0.23 to 1.6 ohms per kilometre, depending on conductor size, ensuring effective fault current handling.

Pilot cores insulated with EPM (Ethylene Propylene Monomer) provide monitoring capabilities, allowing continuous assessment of cable condition and early detection of potential problems. These cores typically carry monitoring signals or earth fault detection systems that enhance operational safety.

The ECC (Earth Continuity Conductor) variant replaces one pilot core with a dedicated earth conductor, providing enhanced fault current return path capabilities. This design is particularly valuable in applications where earth fault currents may be substantial or where additional safety margins are required.

Inner and outer sheaths constructed from CR (Polychloroprene Rubber) provide exceptional resistance to oils, chemicals, ultraviolet radiation, and weathering. This dual-sheath construction creates multiple barriers against environmental hazards whilst maintaining flexibility.

The reinforcement system utilises open nylon braiding with a minimum of 16 strings, providing mechanical protection against crushing, impact, and abrasion. This reinforcement allows the cable to withstand the mechanical stresses associated with dragging, reeling, and installation in harsh environments.

Mechanical Properties and Installation Considerations

The minimum bending radius specification of nine times the overall cable diameter ensures that installation and operation do not compromise the cable's integrity. For the largest cables with diameters approaching 90mm, this translates to bending radii of approximately 810mm, which must be considered during installation planning and reel design.

The cables demonstrate exceptional resistance to abrasion, a critical characteristic in mining applications where cables may contact rough surfaces or be subjected to particulate matter. The combination of tough outer sheathing and mechanical reinforcement provides protection against the abrasive conditions commonly encountered in mining environments.

Oil resistance becomes particularly important in mining applications where hydraulic equipment operates in close proximity to electrical cables. The CR sheathing materials resist swelling, hardening, or other degradation when exposed to hydraulic fluids, lubricating oils, or fuel products.

Ultraviolet and sunlight resistance ensure that cables can withstand prolonged exposure to outdoor conditions without degradation. This characteristic is essential for open-pit mining operations where cables may be exposed to intense South African sunlight for extended periods.

Potential Issues in Mining Applications: Frequently Asked Questions

Understanding the challenges that mining cables face in real-world applications helps engineers and technicians make informed decisions about cable selection, installation, and maintenance. The following questions address the most common concerns encountered in South African mining operations.

Question 1: Can this cable withstand the mechanical stress during dragging and reeling operations?

The mechanical design of SANS Type 633 cables specifically addresses the demanding requirements of dragging and reeling applications. The Class 5 flexible copper conductors provide the necessary flexibility to withstand repeated bending cycles without conductor fatigue. The individual strands in these conductors are fine enough to flex easily whilst maintaining electrical continuity even under mechanical stress.

The nylon braiding reinforcement system distributes mechanical loads across the cable structure, preventing localised stress concentrations that could lead to failure. This reinforcement system works in conjunction with the dual CR sheathing to create a cable structure that can withstand both tensile loads during dragging and compressive forces when wound on reeling drums.

Maximum tension ratings range from 1.1 kN for the smallest cables to 5.4 kN for the largest, providing substantial mechanical strength for handling operations. These ratings ensure that normal installation and operational stresses do not exceed the cable's design limits, maintaining both electrical and mechanical integrity throughout the cable's service life.

Question 2: How does the cable perform in chemically aggressive or oily environments?

Mining environments frequently expose cables to various chemicals, oils, and corrosive substances. The SANS Type 633 cable's construction specifically addresses these challenges through careful material selection and design.

The CR (Polychloroprene Rubber) sheathing material provides excellent resistance to a wide range of chemicals commonly encountered in mining operations. This includes hydraulic fluids, cutting oils, diesel fuel, and various process chemicals used in mineral extraction and processing. The material resists swelling, cracking, and degradation when exposed to these substances, maintaining the cable's protective integrity.

Testing has demonstrated that the cable maintains its electrical and mechanical properties even after prolonged exposure to mineral oils and synthetic hydraulic fluids at elevated temperatures. This performance characteristic is particularly important in applications where cables may be submerged in or regularly exposed to these fluids.

The tinned copper conductors and screens provide additional protection against corrosion in aggressive environments. The tinning process creates a barrier that prevents the underlying copper from oxidising, even when exposed to moisture and chemical contaminants that may penetrate the outer sheathing over time.

Question 3: Is ultraviolet degradation a concern in open-pit mining operations?

Open-pit mining operations subject cables to intense ultraviolet radiation from prolonged sun exposure, particularly in South Africa's high-altitude mining regions where solar radiation intensity is elevated. The SANS Type 633 cable design specifically addresses this challenge through UV-resistant material formulations.

The CR outer sheathing incorporates UV stabilisers that prevent polymer chain breakdown when exposed to ultraviolet radiation. These stabilisers work by absorbing UV energy and dissipating it as heat, preventing the formation of free radicals that would otherwise degrade the polymer structure.

Accelerated aging tests simulate years of UV exposure in controlled laboratory conditions, demonstrating that the cable maintains its mechanical properties and electrical integrity even after prolonged exposure equivalent to many years of outdoor service. The sheathing retains its flexibility and does not become brittle or develop surface cracking that could allow moisture ingress.

Field experience in South African mining operations confirms this laboratory performance, with cables maintaining their appearance and functionality after years of exposure to the country's intense sunlight and varying weather conditions.

Question 4: What about temperature extremes—will the cable crack in cold climates or degrade in heat?

Temperature extremes present significant challenges for cable materials, particularly in South African mining operations that may experience sub-zero temperatures in winter and elevated temperatures in underground workings or equipment compartments.

At the low-temperature extreme of -25°C, the cable materials maintain their flexibility and mechanical properties. The EPR insulation and CR sheathing materials are formulated to remain flexible even at these low temperatures, preventing the brittleness that could lead to cracking during handling or operation. Impact resistance testing at low temperatures confirms that the cable can withstand mechanical abuse without developing cracks or other damage that could compromise its electrical integrity.

At elevated temperatures up to +90°C, the thermosetting nature of the EPR insulation ensures dimensional stability and maintained dielectric properties. Unlike thermoplastic materials that might soften or flow at elevated temperatures, the cross-linked structure of EPR maintains its shape and electrical characteristics throughout the operating temperature range.

The temperature rating includes consideration of both ambient temperature and the additional heating caused by electrical current flow. Under full load conditions, the conductor temperature may approach the upper limit whilst the cable maintains safe operation without insulation degradation or reduced service life.

Question 5: Can the cable handle unexpected electrical faults like short circuits?

Electrical fault conditions represent some of the most severe stresses that cables encounter during their service life. Short circuit currents can be many times larger than normal operating currents, generating substantial heat and magnetic forces within the cable structure.

The SANS Type 633 cables are designed with short circuit ratings ranging from 3.1 kA to 14.6 kA for one-second duration, depending on conductor size. These ratings ensure that the cable can safely carry fault currents without damage to the conductor or insulation system. The ratings are based on the cable's ability to withstand the thermal stress generated by fault currents without exceeding temperatures that would damage the insulation.

The screening system plays a crucial role during fault conditions, providing a return path for earth fault currents and helping to clear faults quickly. The combined screen resistance values ensure that sufficient fault current can flow to operate protective devices promptly, minimising the duration and severity of fault conditions.

Magnetic forces generated during short circuit conditions can be substantial, potentially causing conductors to move within the cable structure. The cable's construction, including the lay of the conductors and the mechanical reinforcement, is designed to withstand these forces without compromising the cable's integrity.

Question 6: What measures ensure worker safety in case of earth faults?

Worker safety represents the paramount concern in mining operations, and earth fault protection is a critical aspect of electrical safety systems. The SANS Type 633 cable design incorporates several features that enhance safety during earth fault conditions.

The triple-screened design provides multiple paths for fault currents, reducing the likelihood of dangerous voltages appearing on exposed metalwork. Each power core has its individual screen, and these screens are connected to create a comprehensive earthing system that helps maintain safe conditions during fault situations.

The ECC (Earth Continuity Conductor) variant provides an additional earth conductor that enhances the fault current return path. This additional conductor reduces the resistance of the earth return circuit, ensuring that earth fault currents are sufficient to operate protective devices quickly and reliably.

Pilot cores can be utilised for earth fault monitoring systems that continuously check the insulation condition of the cable and connected equipment. These systems can detect developing earth faults before they become dangerous, allowing maintenance to be scheduled before failures occur.

The cable's construction minimises the risk of earth potential rise (EPR) during fault conditions. EPR occurs when fault currents flow through earth paths with significant resistance, creating dangerous voltages between different earthed points. The low-resistance screening system helps minimise this risk by providing effective fault current paths.

Question 7: Is this cable compliant with environmental and safety regulations?

Modern mining operations must comply with increasingly stringent environmental and safety regulations, both locally and internationally. The SANS Type 633 cables are designed to meet these requirements whilst providing the performance characteristics needed for demanding mining applications.

RoHS Directive 2015/65/EU compliance ensures that the cable materials do not contain hazardous substances above specified thresholds. This compliance is particularly important for mining companies with international operations or those supplying to international markets where RoHS compliance is mandatory.

REACH Directive EC 1907/2006 compliance addresses the registration, evaluation, authorisation, and restriction of chemicals used in cable manufacturing. This compliance provides assurance that the cable materials have been assessed for environmental and health impacts and that appropriate risk management measures are in place.

SANS compliance ensures that the cables meet South African national standards for construction, testing, and performance. These standards are developed specifically for South African conditions and applications, providing confidence that the cables are suitable for local mining operations.

The manufacturer's ISO/IEC 17025 and IECEE CBTL accredited testing facility ensures that all compliance testing is conducted to international standards with full traceability and documentation. This accreditation provides confidence in the test results and supports the compliance claims made for the cable products.

Sustainability and Environmental Responsibility

Modern mining operations increasingly focus on environmental responsibility and sustainability, recognising that long-term success depends on minimising environmental impact whilst maintaining operational efficiency. The SANS Type 633 cable design and manufacturing processes reflect this commitment to sustainability.

The manufacturer's commitment to net-zero emissions targets demonstrates recognition of the climate change challenges facing the mining industry. This commitment extends beyond the manufacturing process to include the entire lifecycle of the cable products, from raw material sourcing through to end-of-life recycling.

Alignment with United Nations Sustainable Development Goals provides a framework for evaluating the environmental and social impact of cable products. This alignment ensures that the cables contribute to broader sustainability objectives whilst meeting the technical requirements of mining operations.

The cables' extended service life reduces the frequency of replacement, minimising the environmental impact associated with manufacturing, transportation, and installation of new cables. The robust construction and high-quality materials ensure that the cables provide reliable service for many years, reducing the total environmental footprint per unit of service provided.

Recycling services for end-of-life cables help to recover valuable materials and prevent them from entering waste streams. Copper, in particular, has significant recycling value and can be processed into new products with minimal environmental impact compared to primary copper production.

The use of materials that comply with environmental regulations ensures that the cables do not contribute to environmental contamination during their service life or after disposal. This compliance is increasingly important as environmental regulations become more stringent and enforcement becomes more rigorous.

Technical Specifications and Performance Data

Understanding the detailed technical specifications enables engineers to properly specify, install, and operate SANS Type 633 cables in mining applications. The comprehensive specification data provides the information needed for electrical calculations, mechanical design, and safety assessments.

Current ratings ranging from 105 to 260 amperes for different conductor sizes provide flexibility in matching cable capacity to load requirements. These ratings are based on standard installation conditions and may need adjustment for specific environmental conditions or installation methods.

DC resistance values at both 20°C and 90°C enable accurate calculation of voltage drops and power losses under various operating conditions. The resistance increases with temperature, and calculations must account for both ambient temperature variations and heating due to current flow.

Reactance values enable calculation of impedance for AC applications, which is essential for protection system coordination and fault current calculations. The relatively low reactance values reflect the cable's construction with close conductor spacing and effective screening.

Screen resistance values determine the cable's ability to carry earth fault currents and influence the performance of earth fault protection systems. Lower resistance values provide better fault current capability but may require larger screen conductors.

Short circuit ratings provide the maximum fault current that the cable can safely carry for specified durations without damage. These ratings are essential for coordination with protective devices and ensuring that the cable can withstand system fault conditions.

Weight specifications are important for mechanical design of cable support systems, reeling drums, and installation equipment. The cables range from 720 kg/km for the smallest size to over 1300 kg/km for the largest ECC variants, requiring substantial support structures and handling equipment.

Overall diameter specifications influence the design of cable routes, trenches, and protective systems. The diameters range from approximately 71mm to 90mm, requiring consideration in the design of cable management systems.

Installation and Maintenance Considerations

Proper installation and maintenance are essential for achieving the full service life and performance potential of SANS Type 633 cables. Understanding the installation requirements and maintenance practices helps ensure reliable operation throughout the cable's service life.

The minimum bending radius requirement of nine times the overall diameter must be observed during installation and operation. Violating this requirement can cause internal damage to conductors or insulation that may not be immediately apparent but can lead to premature failure.

Cable pulling tensions must remain within the specified limits to avoid damage to the cable structure. The maximum tension ratings provide guidance for installation planning, but actual pulling tensions should be monitored during installation to ensure compliance.

Proper termination techniques are essential for maintaining the cable's electrical and mechanical integrity. Terminations must provide environmental sealing, stress relief, and proper electrical connections to ensure reliable long-term performance.

Regular inspection and testing can identify developing problems before they result in failures. Visual inspection of the cable sheathing, mechanical connections, and support systems should be conducted regularly, with any damage or deterioration addressed promptly.

Electrical testing, including insulation resistance and partial discharge measurements, can detect deterioration of the cable's electrical properties. These tests should be conducted according to established schedules and whenever problems are suspected.

Environmental monitoring of cable installations can help identify conditions that might accelerate cable deterioration. Temperature, moisture, chemical exposure, and mechanical stress should be monitored and controlled where possible.

Conclusion

The SANS Type 633 and 633-ECC 19/33 kV mining cables represent a comprehensive solution to the demanding electrical infrastructure requirements of South African mining operations. Their design reflects decades of experience in understanding the unique challenges presented by mining environments and the critical importance of reliable electrical power in these applications.

The cables' combination of electrical performance, mechanical durability, and environmental resistance makes them particularly well-suited to the harsh conditions encountered in South African mining operations. From the deep gold mines of the Witwatersrand to the vast iron ore operations of the Northern Cape, these cables provide the reliable power distribution that keeps the mining industry operational.

The comprehensive range of conductor sizes, the availability of both standard and ECC variants, and the extensive testing and certification ensure that these cables can meet the diverse requirements of modern mining operations whilst maintaining the highest standards of safety and environmental responsibility.

For mining engineers, electrical contractors, and safety professionals working in South Africa's mining industry, understanding the capabilities and characteristics of SANS Type 633/633-ECC cables is essential for making informed decisions about electrical infrastructure. These cables represent not just a product, but a critical component in the safe and efficient extraction of the mineral resources that drive South Africa's economy.

The ongoing commitment to sustainability and environmental responsibility ensures that these cables will continue to evolve to meet the changing requirements of the mining industry whilst contributing to broader environmental and social objectives. In an industry where reliability, safety, and environmental responsibility are increasingly important, the SANS Type 633/633-ECC cables provide a foundation for successful mining operations well into the future.