The 33kV mobile switching station supplied by Zest WEG
Custom-engineered mobile power solutions company Zest WEG recently supplied a mobile switching station to Mozambique’s national power utility Electricidade de Moçambique (EDM). The specifications and end-user requirements were provided by Mozambican engineering company MESAT, on behalf of EDM.
The 33 kV switching station, complete with 36 kV rated switchgear, is housed within a purpose-built enclosure installed on a double-axle trailer and is said to include all protection requirements to allow for quick connection and safe operation at all times.
Zest WEG Energy Systems senior manager Sollie Herbst says that the company does not have a branch in Mozambique but has an established value-added reseller that provides support in the country.
The switching station was designed and manufactured in South Africa by Zest WEG, and Zest WEG Energy Systems lead project engineer Dumisani Dlamini says that the main challenge on the project was to incorporate all the functionalities required by EDM into a single compact prefabricated solution while, at the same time, minimising the overall size and mass of the unit to allow it to move along public roads without requiring special permits.
In addition, it had to be able to interface with the most recently developed technology for supervision, control and protection and incorporate advanced safety interlocks, both mechanical and electrical. Secondary plant, such as protection relays and devices, was sourced to be in line with EDM’s substation standards.
Dlamini points out that one of the advantages that Zest WEG has in designing projects of this nature is its ability to build its own enclosures. “We don’t make use of standard containers and therefore are not limited by standard sizes,” he says. “By undertaking our own fabrication, we can produce enclosures which can comfortably house all the components of the switching station without any need for compromises due to space restrictions.”
Dlamini adds that the design adopted by Zest WEG simplifies on-site installation. “The unit is completely pre-tested, prefabricated and pre-wired. In essence, it’s a ‘plug-and-play’ solution which can be rapidly deployed to wherever it is needed. There is no need for any support infrastructure on site, such as a specially prepared laydown area, and also no requirement for any craneage, that you would have with a skid-based solution. This means the switching station can become operational shortly after arriving on site.”
“It can be used in emergency applications where it replaces an existing switching station that might have failed or it can be used in a standby role where it assists with temporary 33 kV distribution,” he says. “It’s also ideal for routine maintenance projects, where it might replace – for example – a switching station that is temporarily taken off-line. It’s also, of course, suitable for any project under construction which might need a temporary 33 kV network distribution. It’s a simple operation for this unit to tap into an overhead line and feed power directly to the site.”