Sparks Electrical News March 2022

MCCs AND MOTOR PROTECTION

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Low-voltage switchgear and motor control centres

The difference between contactors and motor starters

tion of the electrical assembly using ABB Ability™ Condition Monitoring for electrical systems (CMES) – offering customers the possibility to detect abnormal situa- tions early. From installation and commissioning to life cycle maintenance and support, ABB distribution solution service is also avail- able to keep customers’ electrical system installations at the highest level of avail- ability and safety. With millions of vertical sections cur- rently installed globally and tens of mil- lions of functional units in service, the low-voltage switchgear portfolio is well positioned to meet your project require- ments.

switchgear. By the beginning of the nine- ties already the first digital solution Insum was added to the portfolio. At the turn of the new century, this evolved into the first fully self-supervising MNS iS with condi- tion monitoring. Nothing has changed in this regard, and ABB continues to pride itself with setting the standard in the low-voltage industry with the introduction again of a true in- novative switchgear solution. NeoGear of- fers an inherent safer, smarter and more sustainable low-voltage power distribution and motor control solution based on lami- nated bus plate technology. In the age of Industry 4.0 the NeoGear and MNS solution platforms have inte- grated capabilities to sense, collect and analyse the current and upcoming condi-

ABB NeoGear and MNS® low-voltage switchgear portfolios offer market lead- ing technology in power distribution and motor control centre applications, con- necting power and automation for pro- cess industry, power and infrastructure customers. As the world’s largest low- voltage switchgear OEM with unmatched domain expertise and local support in more than 40 countries, ABB is truly your local partner. For more than 45 years ABB’s low- voltage solutions business has been set- ting the industry standard for switchgear. Since its inception in the 1970s the MNS design has been based on the fundamen- tal principles of safety, reliability and scal- ability. In the early eighties MNS evolved into the first arc proof withdrawable

E lectric motors are absolutely es- sential to automating innumer- able applications around the world. In most cases, the driving of mo- tors – the supplying of electric power to them – requires some engineered system that must also be compatible with the motor’s winding arrangement. Because these motor-powering systems are often found employing or accom- panying the other electrical control and connectivity devices already covered in this article, we will now review their most common permutations. Only the simplest and smallest de- signs – usually with single-phase mo- tors 5 hp or smaller or three-phase motors 15 hp or smaller – accept direct-on-line (also called across-the- line) connection to the electrical power source without risk of a motor over- draw and a line undervoltage condi- tion. Three-phase motors driven this way can have windings connected in a simple wye (also called star) or delta configuration … and dual-voltage mo- tors (convenient for how they can ac- cept 230 V or 460 V input) have twin coil sets that can run in parallel or (for the higher voltage) in series. Everywhere else, across-the-line mo- tor starts present too many problems for the motor itself as well as systems attached to the motor – including det- rimental electrical effects as well as

excessive wear on mechanical power- transmission components. The design objectives of safety, productivity and precision usually necessitate the use of more advanced motor-driving ap- proaches. Terminology groundwork: The difference between contactors and motor starters In a previous section, we detailed how contactors and relays are distinct com- ponents – despite occasional industry usage of the terms that suggests oth- erwise. Contactors and motor starters are also distinct components. Here the terms are used interchangeably be- cause their core is the same exact tech- nology – a switch capable of handling high voltages. The difference is that motor start- ers have one extra system or systems not found in contactors – an overload relay of some type to cut voltage in- put should that relay sense a motor- overload or thermally compromising condition due to prolonged running overcurrent. Those designated as self- protecting motor starters also include short-circuit protection. Here again, precise use of terminology is key: rather than using short circuit to refer to any electrical malfunction, it’s only proper to use the term when discussing a sudden overcurrent arising from the

Enquiries: www.abb.com

BMG installs variable speed drives on farms for improved efficiencies and energy-savings

BMG’s Smart-Farming agricultural team works closely with farmers throughout southern Africa, assisting them with the selection, installation and operation of new electromechani- cal systems. These projects are designed to improve effi- ciencies, reduce energy consumption and minimise mainte- nance requirements. “Farming operations are not only facing the challenges of the COVID-19 pandemic – which has affected every indus- try globally – but farmers also need to cope with power sup- ply limitations and the rising costs of electricity and water, as well as crippling labour, capital equipment investment and maintenance expenses,” says Carlo Beukes, BMG’s agricul- tural manager. “BMG’s team of agricultural experts – through its ‘Boer Slim’/Smart Farming initiative – is working even harder during lockdown, to offer local farmers sustainability solutions that focus on effective food production. “With the Smart-Farming initiative, we are assisting farm- ers with cost-efficient solutions to improve crop production output, to enhance efficiencies of every operation by con- serving power consumption and to minimise downtime by implementing practical maintenance programmes. It is even more critical now to ensure there are adequate supplies of fresh foods for an anxious and vulnerable population. For this reason, we are also assisting farmers to expand produc- tion to include the supply of additional produce.” In a recent project, the BMG team assisted a local farmer who wanted to accelerate his tobacco drying process and expand crop production, but was restricted by power supply limitations. After the installation of BMG electronic variable speed drives (VSDs), the farmer is able to run 22 tobacco drying containers at once, where previously he could only run and alternate between nine drying containers at any one time. As a result, he has more than doubled his crop pro- duction output. Other positive feedback is that there are no more noticeable voltage dips when the process is started up and wear and tear on mechanical components is reduced. Production is also now less labour intensive, which reduces his shift costs. BMG has also assisted a farmer in the Barkly West area, who was limited by a power supply of only 200 KVA +/- 300 Amps, to significantly reduce the cost of irrigation per hectare. After the installation of VSDs on all pump sets, the power supply is used more efficiently, resulting in improved crop production and expansion of the farmer’s supply of maize, to now also include pecan nuts. Danfoss VLT AQUA Drive FC 202 VSDs – which offer ad- ditional energy savings compared with traditional VSD con- trols – have been designed for water and wastewater appli- cations, including irrigation. These VSDs have been fitted to all pumps in this installation and are controlled by pressure transducers that are set to match the varying demands of different irrigation requirements. The only peripheral com- ponent required was a pressure transducer. Pump control- lers and valves were not necessary for flow control in this system. A notable feature of Danfoss AQUA Drive FC 202 VSDs includes a soft start/stop facility, which prevents water ham- mer on starting and stopping the pumps, thus reducing the possibility of burst pipes. Wear and tear on couplings, pumps

flow of electrical power that has found some un- intended path of travel. Short-circuit protection acts instantaneously to cut off the system from the power source. Another difference between contactors and motor starters is related to how the two com- ponents are rated and specified. Contactors are generally classified by their voltage capacity. In contrast, motor starters are typically rated by their current capacity and the horsepower of the motors for which they’re compat- ible – even while accom- modating inrush current upon start up without nuisance tripping. That is usually done through a slight delay in relay trip- ping – as many motors (especially smaller mo- tors) can reach full oper- ating speed in just a few seconds. Motor starting at its most basic level is clas- sified as manual or au- tomatic. Manual start- ing includes hand-turned on-off switches that simply make or break the motor input circuit when activated by plant personnel. Some ver- sions that qualify as true motor starters (as desig- nated above) incorporate a thermal-overload relay to de-energise the motor if it becomes overheated. In contrast, auto-

and pipes is also reduced. These VSDs are available from BMG in IP55 enclosures, which do not require dedicated panels. This eliminates the need for additional cooling and ventilation, normally required to extract heat during operation. To ensure absolute dependability and the highest per- formance of these systems, BMG was responsible for the installation and commissioning of these projects. Added to this, farmers have the assurance of support from BMG, which is an authorised DrivePro® service partner of Danfoss. With a projected annual power saving of 155 491 kW/hr, BMG expects the farmer to benefit from cost savings of ap- proximately R108 444, with a payback time of less than 12 months. The BMG team is also committed to preventing unneces- sary breakdowns, which is why reliability is the main focus when designing the drive systems for new and upgraded facilities. All BMG components are precisely matched to each other and to application requirements, to ensure high productivity, smooth operation and long service-life. The company’s broad branch network offers original spares and advanced workshop resources that ensure all re- pairs to agricultural components meet pristine OEM stand- ards. BMG provides solutions to all key players in the agricul- tural sector – including local manufacturers of equipment and implements, as well as agricultural re-sellers and the farmer – to assist with the continued supply of fresh foods during the COVID-19 pandemic.

Enquiries: www.bmgworld.net

SPARKS ELECTRICAL NEWS

MARCH 2022