10 December 2012 – Zest Energy, part of the Zest WEG group, has completed a contract awarded by Eskom for the design, construction, supply and commissioning of four 22 kV mobile distribution switching substations, in line with the power authority’s policy of standardising this equipment across the board. Custom trailers have been designed to suit Eskom’s standard equipment dimensions and to remain within the South African road ordinance.

ZestEnergy focuses on two main types of substation and reticulation projects — fixed conventional outdoor substations, typically up to 275 kV, and mobile substation solutions with a variety of voltages to meet different customer needs.

Managing director, Coenraad Vrey says Zest Energy’s mobile power solutions came into being against a background of the high capital cost required for permanent and fixed power generation and substation installations. Today the company manufactures mobile generators with the ability to feed power to multiple locations, which Vrey says is by far the most cost effective approach. In areas where new infrastructure or modification to existing infrastructure is required, mobile substations ensure that the power supply is not interrupted during the construction process. Also, since mobile substations can be supplied within a relatively short delivery period, they can easily be considered for use when fixed substations fail or when maintenance tasks are required on existing substations.

“Backed by WEG’s success with mobile substations in Brazil, we are now manufacturing this technology in South Africa with a high local content. WEG has also sent a mobile substation specialist to assist over the next few months with the growing demand from the African market.

“Although our company started out with an initial focus on power generation, we soon recognised that every power plant needs infrastructure and out of this necessity we introduced substation and co-generation offerings.”
Vrey says the two most important components of a mobile substation are the high-tech transformer and the trailer, which must comply with road and traffic legislation in regard to weight and equipment dimensions. The effects of trailer flex and movement on the integrity of the transformer design are also important considerations.

Caption: A30 MVA 138/69 34.5/13.8 kV mobile substation with a hydraulic goose neck and articulated rear wheels to accommodate tough terrain and any logistic challenge.