Mechanical Technology April 2015

⎪ Special report ⎪

Shaw Controls showcases local

At a Shaw Controls media breakfast function on March 10, 2015 Valter Luiz Knihs (left), Zest WEG Group automation and systems director, along with the Shaw Controls team, showcased the company’s local design and manufacturing capability at its Robertsham premises in Johannesburg. MechTech reports

C ontextualising the Zest WEG and Shaw Controls’ offerings, Knihs says that we are living in an electrical world. Since Thomas Edison developed the first viable incandescent lamp, electricity use has spiralled, first due to the increased use of lighting and electrical machines, then through the electronic revolution and today due to the ever-increasing use of digital devices. In consequence, many ways of gen- erating, distributing and using electric- ity have emerged with the Zest WEG Group offering solutions at every level: WEG electric motors, components and VSDs from Zest WEG; plant installation services from EnI, transformers from WEG Transformers Africa; cogeneration and renewable energy solutions from Zest Energy; backup generators from Generator Set Division; and the electri- cal panels, switch gear and sub-station solutions from Shaw Controls. “We even offer complete industrial automation solutions,” adds Knihs. Shaw Controls manufactures switch- board panels and control systems from 24 V up to 36 000 V (36 kV) for the industrial, mining and infrastructure sec- tors, having recently extended its product offering to encompass low voltage (LV) and medium voltage (MV) applications. Introducing the importance of thor- ough design and quality manufacturing to achieve the safety requirements for elec- trical panels, Knihs shows a few videos highlighting the potential consequences of arc-flash faults. “Electricity is invisible, but when something goes wrong it can cause seri- ous problems, injuries and fatalities,” he says, before showing a video of a substation experiencing arc flash. We see the bright light associated with arc- ing for a few moments before the whole substation explodes into a ball of flame.

Arc flash occurs when the air be- tween electrical conductors changes from being an insulator into a conduc- tor, providing a short-circuit path for current between electrical connections. Once initiated, the severity of an arc flash increases because the electrical resistance of the air decrease as the arc temperature rises. The arc, therefore, draws more and more current causing the conducting path to get hotter and hotter, until something melts or explodes to break the circuit. “An arc flash releases an enormous amount of energy,” says Knihs, before showing another video of a pair of techni- cians opening a panel to do maintenance. Just as the one walks away and while the other is disconnecting a breaker, an arc flash occurs that engulfs the technician in flames. Knihs follows this with a video showing an arc flash underway behind an enclosed panel. After a few moments, an explosion occurs blasting the door off the front of the panel. “Here we see that the arc flash blew out against everyone around them.” As a result of real events such as those shown, Knihs reveals that, two year ago, legislation was passed forbidding any electrical work to be done with the door of an energised electrical panel open. The door must be kept closed to shield people in front of the equipment from the effects of an arc flash. In addition, manufacturers must prove that electrical panels can resist a gas explosion without allowing anything to be projected into the space in front of and around the panel. All explosive pressure must be channelled upwards and out through the top of the panel. “Shaw Controls’ products conform to these standards and are tested to prove that they do,” Knihs adds, showing one last video of a panel under test. Once the arc flash is initiated, we see a burst

of flame projected safely out of the roof of the panel. Moving on to Shaw Controls’ efforts to prevent arc flash and cope with its ef- fects, Knihs says: “Shaw Controls offers a complete product line from MV switch- gear to LV withdrawable motor control centres (MCCs), which are all locally manufactured and independently certified in accordance with IEC 62271‑200 and IEC 61439-1/2 standards.” According to IEC specifications, LV covers applications of up to 690 V, while the MV range is from 1.0 kV up to 52 kV. In addition, Shaw Controls has recently received ISO 9001 accreditation from Bureau Veritas. LV switchboard panels include SC 100, SC 200 to SC 300 models, which can be configured for various applications at different fault levels and current ratings. This gives Shaw Controls the flexibility to be able to offer fit-for- purpose solutions. A recent addition to the Shaw Controls product range is the CCM 03 ZA withdrawable MCC, which is an already well-established product of WEG Brazil. This highly successful MCC solution will now be manufactured in South Africa. All electrical panels include both a mechanical and electrical interlock sys- tem to ensure maximum safety, while the construction itself is robust. Switchgear panels are manufactured using bent steel profiles and enclosed on all sides by steel plating. Over-pressure relief devices in the top provide for pressure relief in the event of internal arcing. Shield-type MV

8

Mechanical Technology — April 2015