Objectives

The primary objective of this tender is to appoint a qualified contractor to perform the refurbishment, repair, testing, and commissioning of 3kV DC traction transformers at Georgedale and Cavendish substations. The goal is to restore these critical substations to full operational condition, ensuring safe, reliable, and efficient traction power supply, thereby enhancing network stability, safety, and operational efficiency.

Scope

The scope includes:

• Design (if required), supply, refurbishment, repair, modification, installation, testing, and commissioning of 3kV DC traction transformers at the specified substations.
• Replacement and installation of components such as bushings, gaskets, breathers, temperature monitoring devices, and safety fencing.
• Oil purification, filtration, and analysis (DGA, moisture, dielectric strength).
• Mechanical repairs, gasket replacements, and leak repairs.
• Electrical connections, interfacing, and verification of protection and control systems.
• Site establishment, access, transportation, and safety compliance.
• Provision of all tools, equipment, materials, and personnel necessary for the complete refurbishment process.
• Assessment of current degraded conditions and detailed reporting on the state of transformers and auxiliary systems.
• Final testing, commissioning, and handover of fully operational transformers.

Technical Requirements

The technical requirements specify that the contractor must:

• Adhere to applicable standards including NEC3, SANS 60076 series, IEC standards, and Transnet specifications.
• Perform comprehensive visual, internal, and mechanical inspections.
• Conduct detailed oil analysis (DGA, moisture, dielectric strength) and ensure oil quality meets standards (SANS 555).
• Replace all gaskets with oil-resistant, non-asbestos materials, ensuring long-term leakproof sealing.
• Carry out cleaning, rust treatment, painting (grey on tank, white on conservator), and corrosion protection.
• Ensure electrical connections are correctly made, phase sequence verified, and protective devices (bushings, Buchholz relays) installed and tested.
• Perform all necessary tests including dielectric, partial discharge, insulation, and operational tests before commissioning.
• Implement environmental protection measures, spill control, and site rehabilitation.
• Ensure safety protocols, site access, and operational constraints are strictly followed.

Skills Requirements

The contractor must demonstrate:

• Proven experience in refurbishment, repair, and testing of 3kV DC traction transformers, preferably within rail or high-voltage substation environments.
• Capability to handle live, operational railway sites with minimal disruption.
• Qualified personnel including certified artisans, electrical engineers, and safety officers with relevant experience.
• Ability to execute complex electrical and mechanical refurbishment activities in accordance with industry standards and safety regulations.
• Strong project management skills, including planning, reporting, and coordination with Transnet’s depot and safety teams.
• Knowledge of environmental and safety compliance, including spill management and site rehabilitation.