To meet the requirements of a Zambian copper mine amid a plant expansion, integrated engineering solutions provider Iritron designed and manufactured fully mobile skid-based substations, serving as an immediate flexible power solution, says Iritron electrical, instrumentation and control department head Ian Nieuwoudt.

The mine was nearing completion in the second quarter of 2025, and an expansion project was subsequently commissioned in August. Iritron was awarded the early works for the project, which included the design and manufacture of seven skid-based substations.

The mine required a fully mobile substation – one that could be moved using bulldozers and would need no additional construction other than to disconnect supply and motor cables, he adds.

“These units would provide power and control to the distributed operations while allowing [for] the operations to be moved on a weekly basis.”

The project was successfully completed within 29 weeks, including seven weeks for the design phase. Upon the successful completion of the contract, and given the improvements offered by Iritron’s solution, it was awarded two additional skid-based substation contracts.

“Owing to the mine’s future expansion plans, the repeatability of the substations was emphasised, keeping additional requirements to a minimum,” explains Nieuwoudt.

The skid-based solution that the mine had on site prior to Iritron’s involvement necessitated that all the equipment be manufactured and partially assembled in South Africa. The equipment would then be trucked separately to site for full assembly and testing.

This method required a contingent of local labour, which was either not always available or did not have the required skills to complete the installation, he notes.

The process also required additional final site acceptance testing, resulting in additional on-site labour and costs for the mine.

In contrast, Iritron’s solution entailed a single 3 m X 9 m containerised substation package that could be manufactured, fully assembled and tested in South Africa. The unit could then be trucked to site in its entirety.

Upon delivery, the mine site team conducted only minimal work such as offloading the package, bolting on pushing blocks and then removing transport supports. Subsequently, the substation was ready for use, he explains.

Further, owing to the continual implementation of the skid-based substations, there was little physical integration with site activities, with the exception of the equipment that would be fed or controlled by the substation. This ensured that the mine’s expansion activities were not disrupted, adds Nieuwoudt.

Thoughtful Design
The substation is equipped with ring main unit (RMU) medium-voltage switchgears from electricity and automation company Schneider Electric, as well as a transformer and motor control center (MCC). It also includes variable-speed drives (VSDs) from engineering solutions provider Danfoss.

The skid-based substation is completely automated and controlled by the onboard programmable logic controller and architecture from technology conglomerate Siemens, which communicates to the central control room using radio links, further advancing the fully mobile design.

Nieuwoudt adds that the RMU includes surge protection from upstream voltage while the MCC includes power metering and additional surge protection.

The resulting accurate monitoring of incoming power allows for improved fault finding and accurate record keeping of the power used by every skid-based substation.

The substation is also protected by intelligent motor starters such as direct online and VSD starters.

Nieuwoudt notes that the fully mobile design placed the transformer near the containerised substation, posing a fire risk.

Consequently, Iritron ensured that the medium voltage protection relay on the RMU monitors the transformer continuously for any fault conditions, while the substation is manufactured to meet a one-hour fire safety rating.