Proposed Network Strengthening Projects

The Matla – Jupiter project deals with the two proposed 400 kV transmission lines from Matla power station in the Mpumalanga to the proposed Jupiter B substation in Rosherville in Johannesburg which is approximately 130km long.

The project also involves the installation of 400 kV loop-in lines (approximately 500m long) at the existing Nevis substation near Springs for the currently operational line from the Matla power station to the Benburg substation, and the Matla power station to Esselen substation 400 kV overhead lines.
Potential effects of electro-magnetic fields
People are generally exposed to varying levels of Electro Magnetic Fields (EMF) in their daily lives at work and at home as household appliances and other electrical equipment also generate electric and magnetic fields (EMF).

Many studies i.e. epidemiology, laboratory and live animal have been conducted over the past three to four decades to determine whether health effects may arise from exposure to EMF.

The main focus of the research has been on a possible association between long term exposure to magnetic fields and childhood leukemia. The suggestion for this health outcome stems mainly from some epidemiological studies. No evidence of a causal relationship between magnetic field exposure and childhood leukemia has been found and no dose-response relationship has been shown to exist between EMF exposure and biological effects.

The guidelines for electric and magnetic field exposure set by the International Commission for Non-Ionising Radiation Protection (ICNIRP) receives world-wide support and are endorsed by the Department of Health in South Africa. Calculations of electric and magnetic field levels created by overhead power lines have shown that areas where members of the public may be exposed (at the servitude boundary and further away from the line) are well within the ICNIRP guidelines. Where necessary and where field levels exceed the ICNIRP guidelines within the servitude, techniques exist to reduce the field levels.
Background of the purpose of the project
The 2008 feasibility study conducted for the proposed project assessed what the load forecast and the transfer capability of the power lines supplying the Johannesburg East area would be without any planned upgrades of this transmission system for the next 20 years. The results clearly indicated that by 2009 the existing network will not be able to meet the forecasted load in an emergency situation where one of the lines supplying/within the area was out of operation. It is further predicted in the feasibility study that by 2018 the current network will not be able to transfer enough power into the eastern areas of Johannesburg under normal operating conditions and capacity.

Johannesburg City Power has predicted an estimated 400 MW of demand load growth in the Modderfontein area alone during this period. This load would have to be supplied off the existing Esselen and Croydon substations servicing the area that relies on the existing transmission network capacity that is deemed to be insufficient to cater for this anticipated increase in demand. A key source of power to the area is the Kelvin power station (operated by City Power), with a maximum generation capability of 600 MW.

Should Kelvin power station ever stop operating, it will become Eskom’s responsibility to ensure that the power demands of the area are met. This would require that an additional power supply of approximately 1000 MW will have to be transmitted into the Johannesburg East area.
In order to meet the demand side requirements of the above scenario the necessary transmission system upgrades have been identified as follows:

• Disconnect the existing Benburg substation – Matla power station line from Benburg substation;
• Turn the present Esselen substation – Matla power station line into Benburg substation to form a 2nd Benburg substation – Esselen substation line;
• Establish a new substation near Jupiter substation (proposed Jupiter B substation at Rosherville);
• Establish two new lines to the proposed Jupiter B substation from the existing Matla -Benburg line servitudes and cutting into the existing Matla power station – Benburg substation and Matla power station – Esselen substation lines. Build both new Matla power station -proposed Jupiter B substation lines with 2000 MW conductor to 400 kV specifications (initially operated at 275 kV);
• Link the existing Jupiter substation to the proposed Jupiter B substation; and
• Upgrade the Jupiter substation – Prospect substation line to 2000 MW conductor capacity.

Should Kelvin power station no longer generate power, then the required North Rand strengthening component of the overall project scope of works would have to be implemented prior to its decommissioning. This would require:

• Establish a new substation near Kelvin power station (proposed Sebenza substation;
• Establish a 275 kV busbar at North Rand substation with 2 x 250 MVA, 275/132 kV transformers;
• Operate the two Esselen substation-North Rand substation lines at 275 kV. These lines are already built at 275 kV load capacity but operated at 132 kV at present;
• Establish a 275 kV busbar at the proposed Sebenza substation;
• Build two, Sebenza substation-North Rand substation 400 kV lines (initially operated at 275 kV) approximately 12 km;
• Build two, Sebenza substation – Prospect substation 400 kV lines (initially operated at 275 kV) approximately 15 km; and
• Build a 3rd Apollo substation – Esselen substation line with 2000 MW conductor capacity, approximately 11 km.

It is clear from the above scenario that a substantial upgrade of the existing Transmission network in the Johannesburg East area will have to be undertaken in order to meet projected increased electricity demand in the short term future. Further to the required transmission system upgrades detailed above, Eskom has also identified additional strengthening measures that are necessary for increasing the capacity within the central Johannesburg area.

The existing Craighall substation (along Republic Road in Randburg) will be supplied with an additional 400 kV line from the proposed Sebenza substation and the construction thereof will also form part of the overall application for environmental authorisation for the project components detailed in Section 1.3.

Also required to strengthen the supply to the central Johannesburg area is the construction of a 400 kV loop-in line approximately 500m long at the proposed Jupiter B substation for the existing Jupiter substation to Fordsburg substation line.