Sparks Electrical News April 2022

CABLES AND CABLE ACCESSORIES

6

Aluminium does this quicker than copper so extra vigilance is re- quired. All joints should be regularly inspected by torque and visually. The main failure mode would be the slow degradation of the joint with the result of a loose connection and product damage. 3) Correct connectors Use the correct connectors when doing terminations. That means fol- lowing all instruction on the use of the connector as well as the crimper to be used. Avoid direct clamping of aluminium especially stranded cable, rather use lug conversion. Lug manufacturers can offer advice in this regard. 4) Clamp connectors Ensure that the circuit breaker manufacturer sanctions Aluminium con- ductors. Remember the Aluminium conductor is going to be bigger for a current rating. Powermite’s range of robust cable extension reels is packed with features to provide customers with reliable, robust and safe performance. The Gen 2 plastic XREEL series is manufactured from Polyamide 6 and PC/ABS. It delivers enhanced ben- efits such as impact resistance combined with high robustness; high thermal stabil- ity; great insulating qualities; high impact strength; UV resistance according to ISO 4892-2; and high abrasion and weather resistance. The unit is offered in two sizes, 250 mm and 310 mm, with cable lengths of up to 33 and 50 m respectively. With safety and convenience central to its design, the XREEL features a patented brake system which is centrally placed within the axle, a sturdy stand with wide supporting points and openings in the drum for water drain- age. The central panel is available in different versions and can accommodate up to four plug points ensuring optimum versatility for end-users in the industrial sectors. Robust ergonomic cable extension reels Enquiries: www.powermite.co.za P articularly aware of the contamination risks of a nosocomial infection, Axon Cable has incorporated the technology of silver ion micro-flux into intercon- nect solutions to develop Nosofree, an innovative range of antimicrobial medi- cal assemblies. Designed with dedicated jacketing, moulding and overmoulding ma- terials with anti-microbial and anti-fungal properties, they inhibit the growth of viruses and microbes, including bacteria which resist antibiotics. Any plastic insulation including PVC, TPE and PE can be modified with anti- bacterial agents. Material properties such as colour and biocompatibility are not affected by the Nosofree manufacturing process. The antibacterial activity is ef- ficient throughout the whole lifetime of the cable assembly. Antimicrobial medical cable assemblies Enquiries: sales@hiconnex.co.za

Cable carrier systems for extreme applications

plastic materials, to suit exact requirements. BMG’s Kabelschlepp range of cable carrier systems and safe- ty cables − known for high productivity, minimal maintenance re- quirements and reduced downtime − extends from standard in- dividual components to complete system solutions. Applications for Kabelschlepp cable carriers extend from computer plotters and micro-sensitive test and measurement equipment, to rotat- ing reclaimers, offshore drilling rigs and high-speed automated machining centres.

BMG’s extensive portfolio of Tsubaki Kabelschlepp cable carrier systems and safety cables includes S/SX steel cable carriers for heavy mechanical loads in harsh environments, including corrosive conditions. “The S/SX series comprises robust steel cable carriers, with a chain-link sandwich de- sign consisting of two plates welded together for high stabil- ity,” says business unit manager, Carlo Beukes.“ This allows contaminants found in harsh environments to fall through the system when the cable carrier is in motion. Dirt build-up, which normally causes blockages of the stroke system, is prevented.”

Enquiries: www.bmgworld.net

With conventional ca- ble carrier systems, large amounts of foundry sand, corundum or scale can block the stroke system, resulting in failure and sub- sequent downtime. The S/ SX series allows increased unsupported lengths and large additional loads with- out sagging. The stroke system is designed for ex- tended service life. Dividers maintain neat cable sepa- ration and a cover system enhances cable protection. The series is available with a galvanised finish or stain- less steel construction in different dimensions, as well as in durable, lightweight

C opper conductors are by a huge margin the conductors of choice in the LV side of electrical distribution. These can be fixed shape solid busbar types and range of PVC covered cables. Low rating cables have virtually all switched over to a single solid copper conductor away from multiple copper strands from many years back. Indeed, this has had a benefit and speeded up these smaller connections and made them far more unlikely to be a poor connection. Still the most effective way is to double back these small connec- tions giving a larger connection and filling the connectors with more than the minimum copper required. One can never have too much contact in the electrical game. Of course, copper is not the only conductor material around, but it surely is the most widely used in the electrical industry. However, it is also the most likely candidate for theft given the unsatiable desire for scrap and the high copper scrap prices given. This theft has reached alarming proportions in RSA as well as elsewhere and damage to the Discussing your conductor choices

electrical grid borders on industrial/economic sabotage levels! Aluminium has long been proposed as an alternative conductor material and has in the electrical tower distribution network been ex- tremely successful. So why has the same not been in the electrical environment not been similarly successful? All the fittings are unique to the Aluminium lines been fitted they are not compatible/universal to copper overhead lines. The main draw- back on the overhead line is the tensile requirements due to the pull on the conductors and this is easily fixed by having a steel trace within the aluminium cable itself solving the tensile issue and re-enforcing the risk to movement hardening and fracture common to Aluminium and copper alike. Also, great success has been at the munic levels where larger circuit breakers can be connected via bolted lugs. Of course, these lugs are special for the task and still not widely known outside of this industry sector. Aluminium is seen in sectored shape as well as multistranded, with the most successful being the sectored shape, eg like a pie sec- tored solid shape. Besides the correct lug type the crimping style and anti-corrosion grease are absolute musts especially near or at the coast. Covering all open metal is also required as far as is practical. The standard aluminium cables have never performed very well in the writers’ experiences and certainly have been the return and hot connections on many circuit breakers. They require an inordinate amount of precision and observed maintenance all of which negates any cost saving. The risk of any hot connection with the circuit breaker using clamping connects is such that the joint and circuit breaker re- placement costs will far outweigh the savings in material at time of failure! 1) Galvanic corrosion When two metals are in contact with one another, and an electrolyte is present one metal acts as a cathode and the other as an anode in which the anode is slowly dissolved. Never have copper and aluminium in direct contact, it would be better to have a copper connections plated and not bare in any event. Where absolutely necessary use special connectors designed for trouble free connection. Use special anti-oxidation paste in the joint. Cover the area fully with tape/wrap. 2) Plastisizing Over time any clamp type connection (circuit breakers use this in great numbers especially the smaller versions) will reduce the forc- es on the conductors as the hot/cold joint cycles over time. Risks What are the risk areas where we need to take care?

So, one has to ask, is there really a solution to replacing copper conduc- tors? I suspect not totally at this time.

By Kevin Flack

Flack has recently retired from industry and believes he still has valu- able in-depth knowledge of the South African electrical landscape due to wide experiences gained in his 45+ years working career. In these trying COVID-19 times, Flack can provide online training to keep your staff up to date on all aspects of circuit breaker deploy- ment. Email kevin.flack@outlook.com

Example of a poor standard of connection. Aluminium copper in direct contact, small bolts not able to soundly connect, and incorrect crimping method.

SPARKS ELECTRICAL NEWS

APRIL 2022