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.