Zest WEG has completed the delivery of a mobile switching station to Mozambique’s national power
utility EDM (Electricidade de Moçambique), further reinforcing its reputation as a supplier of cost-
effective, custom-designed mobile power solutions.

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 includes all protection requirements to allow for
quick connection and safe operation at all times.

“Mozambique is regarded by Zest WEG as a key strategic market and we’re therefore delighted to
have successfully completed this order,” comments Sollie Herbst, senior manager, Energy Systems at
Zest WEG. He adds that while Zest WEG does not have a branch in Mozambique, it has an
established Value-Added Reseller in the country able to provide support – in conjunction with Zest
WEG in South Africa – to customers in the country.

The switching station was designed and manufactured in South Africa by Zest WEG with the lead
engineer on the project being Dumisani Dlamini, energy systems engineer within the Energy Systems
division of the company. The specifications and end-user requirements to be met were provided to
Zest WEG by MESAT, a Mozambican engineering company acting on behalf of EDM.

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 any special
permits being required.

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.”

Zest WEG is normally able to supply its mobile switching stations within 28 weeks of receiving an
order but, in this case, was able to slightly better this time. “The design and fabrication proceeded
very smoothly and we were able to deliver well within the promised timeframe,” says Dlamini.
Commenting on the possible applications for the switching station, Herbst says that EDM stipulated
that it should be a self-contained, multi-purpose unit able to accommodate a range of operational
scenarios, including working in areas with limited infrastructure.

“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.”

The mobile system delivered to EDM follows hard on the heels of another recent notable success in
Africa, which saw Zest WEG supplying a 50 MVA mobile sub-station, one of the largest ever built in

South Africa, as well as a 33 kV mobile switching station, to Electricité de Guinée, the national
electricity utility in the West African country of Guinea.

The scope of the turnkey project included three trailers with specialised equipment, one of them
being a cable reel trailer with all power and control cabling needed to connect the mobile sub-
station and the mobile switching station trailers into an integrated mobile energy system.

“The latest Mozambican order as well as the Guinean project highlight Zest WEG’s ability to design
and manufacture mobile solutions for almost any application, anywhere in Africa,” says Herbst. “We
believe that there is a significant and growing demand for solutions of this type given that the
continent’s electrical infrastructure is growing very rapidly. These contracts clearly underline our
ability to meet this demand.”

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