Tender Summary: Medium Voltage Infrastructure Maintenance (6.6kV & 11kV)

Objectives

The primary objective is to ensure the safe, reliable, and fully compliant operation of medium voltage electrical infrastructure operating at 6.6 kV and 11 kV. This will be achieved through structured planned preventive maintenance, comprehensive diagnostic testing, and authorised corrective maintenance interventions to minimise downtime and extend asset lifespan.

Scope of Work

The contract covers the maintenance of five electrical substations and associated transformers. The scope encompasses:

• Preventive Maintenance: Visual and mechanical inspections, cleaning, lubrication, torque checking, and condition assessments of switchgear, circuit breakers, busbars, transformers, cables, and earthing systems.
• Testing & Diagnostics: Functional interlock testing, contact resistance measurements, circuit breaker timing tests, insulation and winding resistance testing, thermographic scanning under load, protection relay testing, and transformer oil analysis.
• Corrective & Emergency Services: Fault location and repair, cable jointing/termination replacement, breaker mechanism repairs, and provision of emergency call-out rates with defined response times for critical and non-critical failures.
• Documentation: Submission of asset-specific maintenance reports, consolidated infrastructure condition reports, defect registers with risk ratings, cable route updates, and root cause analysis for major failures.

Technical Requirements

Bidders must submit the following mandatory documentation and comply with specified standards:

• Valid calibration certificates for all designated test equipment.
• A company profile detailing firm background, years of experience, and relevant industry capabilities.
• Two reference letters demonstrating prior experience with 6.6 kV and 11 kV systems.
• A comprehensive safety file to be provided before work commencement.
• Compliance with the Government Procurement General Conditions of Contract (July 2010).
• Detailed pricing schedules covering planned maintenance, specialised testing, corrective labour categories, emergency mobilisation, spare parts/materials, and technical reporting.
• Failure to submit any compulsory documentation results in immediate disqualification.

Skills Requirements

Personnel deployed must hold a minimum diploma in electrical engineering and possess documented authorisation and practical experience in medium voltage infrastructure maintenance. The service provider must demonstrate capability across multiple specialised roles, including:

• MV authorised switching persons and qualified electrical technicians
• Protection and control specialists
• Cable jointing specialists
• Electrical engineers/technical specialists and competent supervisors
• General electrical assistants

Explanation of Technical Terms & Services

Several specialised power industry terms and procedures are referenced in this tender:

• DGA (Dissolved Gas Analysis) & BDV (Breakdown Voltage): Laboratory tests performed on transformer oil to detect internal faults (DGA measures gases produced by electrical arcing/overheating) and assess dielectric strength (BDV).
• SF₆ Gas Checks: Verification of sulphur hexafluoride gas levels and quality in insulated switchgear and circuit breakers, which acts as an arc-quenching and insulating medium.
• Buchholz Relay Checks: Inspection of a protective gas-actuated device installed on oil-filled transformers to detect internal faults like gas accumulation or oil leakage.
• Primary & Secondary Injection Testing: Diagnostic methods used to verify the accuracy and functionality of protection relays and current transformers without energising the full high-voltage circuit.
• HV Withstand Testing: High-voltage insulation testing applied to cables and equipment to verify their ability to withstand operational stress without breakdown.

Evaluation follows an 80/20 weighted scoring system (Price/Preference) aligned with national procurement regulations, requiring valid BBBEE documentation for specific goal points.