Motor Control Centres Archives - International Mining

WEG Automation Africa has come to the rescue of a tin mine in the Democratic Republic of Congo, providing a containerised substation and control room solution that circumvented the challenging logistics associated with accessing the operation.

The company, formerly Shaw Controls, put the contract win down to an innovative and fit-for-purpose design.

Tyrone Willemse, Business Development Consultant – Projects and Contracts at WEG Automation Africa, said the substations are each housed in a 6-m-high cube container, with a total of 14 units supplied, comprising MV rooms and LV rooms.

Willemse says: “The unit’s dimensions and robustness had to allow for a long journey, including along a very difficult 200 km road to reach the mine site.”

He added: “Every part of the process plant has its own designated MCC (motor control centre) that provides electrical power and control for areas including the primary crushing circuit, the plant feed, regrind mill, tailings thickener, and the product dewatering and handling circuits.”

In addition to meeting safety compliance regulations, the design includes three-way locking systems, LED lighting, fire detection systems and a safety interlock to the fire system for air conditioners. Backup power supply is provided to all the exit lighting, according to WEG. To ensure easy cable entry, meanwhile, glanding plates were carefully located not to overlap with the container’s support beams.

“Working in close collaboration with the engineering house, careful planning could be done upfront to ensure that nothing was overlooked,” Willemse said.

“In the design, full consideration was given to the placement of elements like platforms, walkways, doors, viewing windows and air conditioning units. We also took responsibility for the logistics of getting everything to site.”

Willemse highlighted that this turnkey solution demonstrated WEG Automation Africa’s containerised substation design and engineering capability, as well as its full local manufacturing capacity, which he said, lifted the company above other MCC manufacturers or assemblers.

The containerised solution comes with a full data pack, quality control documentation and an operation and maintenance manual in accordance with ISO9001.

“With our expertise, capacity and experience of working in Africa, we were able to reduce the risk and turnaround time by tackling the entire contract in-house,” Willemse said. “The extensive testing and cold commissioning enabled by our modus operandi and facilities also gave the mine peace of mind that the unit would function as required when it arrived on site.”

The replacement of steel by aluzinc in the manufacture of Shaw Controls motor control centres (MCCs) has brought with it a range of benefits, Shaw’s Senior Manager Operations, Anderson Kohler, says.

“Traditionally, we used only steel for our MCCs, which needs to be powder coated in order to protect it from corrosion,” Kohler said. “This made it necessary to follow quite a long process in completing our products – a process which aluzinc can now simplify and speed up.”

The usual process of preparing MCC panels includes welding, grinding and prewashing before the powder coating painting process can take place. These phases can now be bypassed by using aluzinc; a material that resists corrosion without a protective coating being applied.

Kohler highlighted the extended lifespan of aluzinc, which comprises 55% aluminium, 43.5% zinc and 1.5% silicon – manufacturers of the product guarantee it will last for about 35 years before any major maintenance is required.

He said the powder coating of steel panels complicates the earthing requirement on an MCC, as the paint layer insulates the panel and prevents conductivity. “This means that technicians and installers must take special care to ensure that proper contact is made between the unit and the earth connection,” he said.

For instance, the use of star washers must be strictly enforced among installation staff. Alternatively, certain areas of the MCCs are left unpainted to allow for earth connections. This does raise the concern that it only takes a small oversight and the earthing will not be fully effective, Kohler pointed out. The use of aluzinc eliminates this issue as there is no longer a paint layer between the earth connection and MCC panel, he said.

Shaw Controls said: “There is also the possibility of painted parts being scratched or damaged during transport and installation. When this occurs, it leads to the time consuming task of being returned to the factory for proper powder-coating, further delaying the installation and commissioning process. Indeed, if there is a need to weld again for any reason, then there is a repeat process of grinding and pre-washing before painting again.”

Kohler said the corrosion-resistant properties of aluzinc allowed parts to be kept in stock, ready for quick assembly; something not possible with mild steel due to corrosion.

“By introducing the use of aluzinc in the manufacture of our MCCs, we can reduce the lead time on components by as much as two to three weeks, and this is a time-saving that we can pass on to our customers by delivering more quickly,” he said.

There are also environmental benefits to using aluzinc as a replacement, said Kohler. No welding means a saving on gas and electricity, for instance, while no pre-washing obviates the need for harsh chemicals. In the painting process, there is invariably waste created through surplus paint that must be carefully disposed of in terms of environmental regulations.

Shaw Controls, a Zest WEG company, has over 30 years’ experience as a manufacturer of MCCs, distribution boards, medium voltage switchgear, control desks, PLC and instrumentation enclosures, portable and containerised substations, E-Houses and various other electrical enclosures.

WEG Automation Africa overcomes logistical challenges at DRC tin mine

aluzinc simplifies and speeds up Shaw Controls’ MCC manufacturing process