MechChem Africa March-April 2022

Zest WEG delivers its biggest mobile substation yet Leveraging its considerable in-house expertise and local manufacturing capability, Zest WEG has custom designed and manufactured a mobile substation solution for Guinea – its biggest such mobile unit yet manufactured in South Africa. The innovative 50 MVA substation will perform a range of duties for the Utility Company of Guinea, including providing emergency and standby power.

The largest mobile substation built to date by Zest WEG in South Africa is designed for minimum installation time, to be suitable for both temporary or permanent installations and to be used in a range of applications.

L everaging its considerable in-house expertise and local manufacturing capability, ZestWEGrecently custom designed and manufactured one of the largest mobile substations ever built in South Africa. The 50MVAmobile substation – destined forGuinea – includes a dual voltage ratedmo- bile transformer produced by WEG in Brazil, according to Bernard Mitton, engineering team leader for integrated solutions at Zest WEG. The substation will be commissioned in 2022. “This is a full turnkey project procured by Robustrade in Dubai for the Utility Company of Guinea, called Electricité De Guinée,” says Mitton. “Our in-house teamco-ordinated the electrical, civil andmechanical designs, aswell as theengineering solutions for thecustomer.” The full project includes three trailers of equipment, and allows the end-user to step down power from the main national grid at various geographic points as required. High voltage power is tapped from existing over- head lines with a specifically designed and manufactured tee-off solution connecting the supply into the mobile substation, where it is stepped down from110 kV or 60 kV to 20 kV or 30 kV depending on requirements. “From the 50 MVA mobile substation, the supply is then distributed to a 30 or 20 kVmobile switching station, containing an

incomer and five feeders,” Mitton explains. “Mini-substations can be fed directly, or a cable can feed to a junction box in the field, usually where there is an existing cable in the ground.” As part of the project, ZestWEGdesigned and supplied a cable reel trailer with all the power and control cabling needed for the mobile transformer and mobile switching station. Included on this trailer are 30 kV field junction boxes to assist with the cable

connection between exiting cables already installed and the supply cables from the mobile switching station. These boxes allow for up to three feeder cable connections. The advantage of this design, he notes, is that the junctionboxbecomesa terminationpoint. The termination ends of the on-site cable do not need to be redone, and all that is necessary is a bolt-on connection. “Thismobile substation solution is suitable for both temporary and permanent installa-

New technologies such as hybrid circuit breakers have been employed, along with disconnectors, earthing switches, ring-type current transformers, inductive voltage transformers and surge arresters.

30 ¦ MechChem Africa • March-April 2022