Objectives

The primary objective of this tender is to establish a standard for the refurbishment and repair of power transformers (ranging from 10 MVA to 40 MVA) used within the Rustenburg Local Municipality's electricity distribution network. The standard aims to guide contractors and municipality personnel in assessing, repairing, refurbishing, testing, and certifying transformers to ensure their reliable re-use in substations, whether onsite or offsite.

Scope

This standard covers all aspects related to the repair and refurbishment of power transformers for indoor and outdoor applications, including:

• Transformers in use within the municipality's network earmarked for repairs or refurbishment.
• General requirements for repairs, refurbishment, testing, and certification.
• Onsite and offsite repair activities, including transportation, rigging, storage, and handling.
• Specific procedures for inspections, electrical and mechanical testing, oil analysis, and quality control.
• Environmental, health, safety, and documentation requirements.

Technical Requirements

The technical specifications include, but are not limited to:

• Compliance with relevant standards such as IEC and SANS (e.g., SANS 60076 series, IEC 60450, IEC 60076-10, IEC 60076-5).
• Transformer assessment prior to refurbishment, including visual inspection, testing, and condition verification.
• Refurbishment activities such as tank overhaul, gasket replacement, bushings testing, tap changer inspection, oil regeneration, and component replacement.
• Electrical testing: no load test, load losses, impedance, partial discharge, SFRA, dielectric tests, DGA, noise level, bushing tests, and other diagnostic tests.
• Factory and site acceptance testing with comprehensive reporting and certification.
• Proper storage, handling, transportation, and environmental management during refurbishment and after.
• Installation, commissioning, and warranty procedures.

Skills and Competency Requirements

The contractor must demonstrate:

• Qualified personnel with SAQA-certified riggers and technicians experienced in transformer refurbishment and handling.
• Availability of fully equipped workshop facilities compliant with SANAS or equivalent accreditation, including overhead cranes (minimum 100 tons), vapour drying equipment, and testing bays.
• Capability to perform all specified electrical, mechanical, and chemical tests in accordance with IEC/SANS standards.
• Experience in onsite and offsite transformer repairs, including transportation, rigging, and installation activities.
• Environmental management and safety management systems aligned with ISO 9001, ISO 14001, and OHSAS 18001 standards.
• Provision of qualified site management personnel with appropriate safety certifications (e.g., ORHVS).
• Ability to produce comprehensive documentation, test reports, impact recordings, and warranty commitments.