Electrical equipment supplier Zest WEG Group has extended its market reach into mobile distribution switching, with the successful handover of four 22/11 kV mobile distribution switching stations to State-owned power utility Eskom’s Central Region in February and has received an order for a further two units.
“These four fully integrated units were manufactured by Zest Energy, the subsidiary of Zest WEG Group, and were engineered to suit specific Eskom requirements, including use in different configurations,” Zest WEG sales and marketing director Gary Daines tells Engineering News.
He highlights that the mobile distribution switching stations can be rapidly deployed to a site and can be quickly connected to existing equipment to support substation maintenance or emergency circumstances, thereby improving the availability of Eskom’s electrical network.
“These units were also manufactured in accordance with South African road ordinance requirements to eliminate the need for special transportation permits.”
Further, Daines notes that Zest Energy is involved in different types of substation and reticulation project work, including fixed-type conventional outdoor substations, up to 275 kV, as well as mobile substation solutions, with a variety of configurations and voltages to meet different customer needs.
Meanwhile, Zest Energy projects manager Alastair Gerrard says although Zest WEG has been supplying transformers to Eskom on contract for several years, this is the first time that the group, through Zest Energy, has been tasked with innovating and developing an engineered solution of this kind.
“Working closely with the Eskom project team, we developed this design from scratch to ensure that it meets Eskom’s standards and specifications. The only off-the-shelf component in the entire mobile switching station is the medium voltage (MV) equipment,” he points out.
Gerrard says part of these units’ integrated solution is that all protection systems and supporting systems are on board, enabling switchgear operation to take place in a safe and controlled environment.
Further, Gerrard enthuses that Zest Energy has proved its in-house capability to develop mobile solutions from the various forms designed to meet customer specifications. Subsequently, Zest Energy continues to notice emerging market opportunities that enables it to provide other industrial sectors with custom-engineered mobile solutions.
“Each mobile distribution switching station comprises of an MV switchgear compartment and a switching control compartment, separated by an internal wall. Both compartments can be accessed directly from the outside of the trailer through fold-down single-lever operated doors, with fully incorporated handrails and steps.”
Gerrard adds that there are also sliding doors behind each main door to facilitate the safe use of the switching station during extreme weather conditions.
Zest Energy electrical design engineer Sollie Herbst adds that safety was a major factor during the design phase of the mobile distribution switching stations.
“Despite the space constraints associated with such a solution, all safety aspects were taken into account and catered for to the highest standards,” he says.
“For instance, the unit is fully controllable from a mimic panel in the switching control compartment of the trailer, effectively removing the operator from the vicinity of the breakers in the MV compartment during switching.”
Herbst notes that each mobile distribution switching station’s enclosure is custom built and integrated with a bi-axle, step-deck trailer, which, in turn, is equipped with air suspension and an antilock braking system.
“Each switching station incorporates an 11-panel, fixed-pattern-type MV switchboard, which has been modified to accommodate standard Eskom protection schemes on board,” he says.
The system is also integrated into other standard Eskom auxiliary systems, including metering, alternative current and direct current power supply, as well as the British Thermal Unit energy system that is equipped with batteries and communication.
“Cable entry is designed as a bottom entry through special access doors in the floor of each trailer and each cable can easily be terminated to the MV breaker terminals,” Herbst explains.
The switching stations can also be used in coastal or polluted regions, owing to its double-insulated enclosure walls and roof, as well as in (the) noncorrosive materials of construction.
“The Zest Energy team offers extensive expertise in the power generation and energy industry. Whether a single solution or a combination of power generation solutions is required, Zest Energy’s services include the supply, manufacture, erection and maintenance of power generation equipment, ranging from complete power plants and cogeneration systems to custom engineered power generation and integrated energy solutions for new or existing mining and industrial companies,” Herbst concludes.
